# High Oil Consumption



## pathological (Nov 25, 2011)

I have a 2992 Pathfinder 3.5 SE with 130,000 miles. It began using oil suddenly to the tune of 1 qt/1000 miles. I've changed the oil and filter regularly (10w30) and there is no evidence of leakage or smoke out the exhaust. The spark plugs are clean, compression is very good across the board and there are no "trouble" codes. I have replaced the PCV valve and R/H valve cover thinking the internal PCV baffles might be plugged. The PCV hoses are clean and there are no screws missing from the power valve butterflies. There is evidence of oil in the intake manifold and upper and lower plenums. This tells me there is a backpressure problem. Could I have a catalytic converter that is plugging up and still not setting a code? If not, does anyone have any other ideas?


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## jdg (Aug 27, 2009)

pathological said:


> I have a 2992 Pathfinder 3.5 SE with 130,000 miles.


Dear Mr. Future Man,
Can you tell me where people of your time have found new sources of raw petroleum based products?

Thanks...
Mr. Present Day Guy


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## smj999smj (Jan 1, 2006)

I have heard of issues with the rings in the VQ35DE's. The cylinder bores apparently have been designed with a slight taper and the secondary compression and the oil rings don't properly tension against the bore, causing the oil burning issue. Updated rings address the issue, but, of course, that requires tearing the engine apart.


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## pathological (Nov 25, 2011)

Dear smj999smj thanks for ignoring the obvious typo of the model year of my Pathfinder. It is a 2002. I did a compression check and got 170 to 180 psi across the board. The book says a normal max pressure should be 178 psi, and that's without squirting oil into the cylinders. That tells me I don't have a broken ring or cylinder wear, but I could be wrong. If I had a plugged converter this could cause backpressure and push oil into the intake, but I am not setting a trouble code and would this account for this much oil consumption? This oil usage didn't happen gradually. Normally the engine would use 1 pt of oil between oil changes (2500 miles). Then suddenly consumption increased to 1 qt/1000 mi. I'm trying to convince myself that it's not a ring problem.


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## IanH (Feb 11, 2003)

If your converter was plugged your gas mileage would be in the gutter....
All the VQ Oil consumption issues from rings I know of were mainly on the rev-up Engines, and when tracked over 50K miles the Oil consumption decreased. 
The VQ is not a particularly good on Oil, I get 2-3 K per Quart.
That being said it does sound like a blow-by issue or Oil being sucked into the intake.
as anyone removed the intake ?


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## pathological (Nov 25, 2011)

I have had the upper and lower plenums off as well as the intake manifold and saw nothing abnormal except oil in the intake and plenums. I do all of my own work on various cars in my "fleet" so I'm kinda familiar with the way things should look and this isn't right. The reason I questioned a partially plugged converter is that I feel power is down slightly and so is gas mileage (from 20 mpg highway to about 18+). Not a lot but still a difference. I'm not excited about changing out converters but I'm also not excited about doing a ring job.
I just recently got a pending MIL code for sensor bank 1 sensor 2 for the aft O2 sensor. It hadn't turned on the light because it was a stored pending code. It hasn't as yet repeated itself in about 50 miles. I know that the downstream sensor checks the condition of the converter, along with fine tuning fuel. sooooo--WTF? over


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## IanH (Feb 11, 2003)

I asked that question because I had two separate V8's that had this same issue, they were sucking Oil into the intake from the Oil gallery. The Fix was some serious application of gasket compound, this fixed it. 
Like you I do nearly all my own work, and I agree it doesn't sound like a typical problem.
How about putting a catch can on the breather and seeing if it is coming from there?


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## IanH (Feb 11, 2003)

BTW I have not had this engine apart so may be completely misleading you


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## IanH (Feb 11, 2003)

re: sensor2 code, 
I had this on my IS300 with 145K and did not see any reduction in mileage, in fact I think its pretty good, not much worse than the SER w/2.0 in town, about 19 vs 21 mpg with same commute, and same on the highway, 26 -27 mpg on longish trips. Did not change the CATS....I used an O2 cheater to remove the code, and passes inspection here in Texas.


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## pathological (Nov 25, 2011)

This problem started with the engine never having been apart from factory new so I don't think a bad gasket could cause the problem of sucking oil from the oil gallery. Furthermore, there is no oil gallery on this engine in the conventional sense. It's not like an American made V8 with a big ole intake manifold. When I removed the intake and plenum I was careful to clean off all old gasket material. The surfaces were clean and smooth when the new gaskets went on and all bolts were torqued 'by the book", but the problem was still the same. 
Using a 'catch can' on the vent hose is a good idea but unless I'm misunderstanding you all this will tell me is that I have blowby. It won't tell me the reason (whether it's from a restricted exhaust or bad rings).


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## thxone (Feb 7, 2012)

I had a 4.0L H.O. Jeep Xj Cherokee, my oil consumption was more evident... any hoses coming from valve covers or going to the Air intake (starting at the air filter if there are connections there) could have baffles in them. On my Jeep these baffles were inside the valve cover. They were badly clogged and this created an oil pressure issue in which it sent pressurized oil through another tube to my air filter box. My engine ingested oil this way until I tracked the issue down. But this is "one" way oil can get into the intake.


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## IanH (Feb 11, 2003)

pathological said:


> This problem started with the engine never having been apart from factory new so I don't think a bad gasket could cause the problem of sucking oil from the oil gallery. Furthermore, there is no oil gallery on this engine in the conventional sense. It's not like an American made V8 with a big ole intake manifold. When I removed the intake and plenum I was careful to clean off all old gasket material. The surfaces were clean and smooth when the new gaskets went on and all bolts were torqued 'by the book", but the problem was still the same.
> Using a 'catch can' on the vent hose is a good idea but unless I'm misunderstanding you all this will tell me is that I have blowby. It won't tell me the reason (whether it's from a restricted exhaust or bad rings).


I agree, but its still worth checking all the hoses for blockages and any possible causes, the alternative is expensive.

Next I would investigate what test pipes are available to replace the Cats, you probably have 3, same as my IS300. 

As you can tell i haven't had much in the way of issues on my Pathy except for the weird loss of power after a hot soak in the summer. happens 1 -3 times a yr since i got it. Its not the fuel pressure regulator, next is check of swirl valves for evidence of jamming. No codes, dealer couldn't find it when it was under warranty and i took it in there with the fault. Idiots turned it off and it recovered by the time they started it.


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## IanH (Feb 11, 2003)

I had a 5.0 Chevy that had a blocked CAT, mileage went to hell, dropped to 70% approx.
came back as soon as the one cat was replaced with test pipe. No problem noticed with Oil consumption, but was relatively low mileage engine and Chevy was not that good anyway. I have doubts that a blocked CAT would do this.....?


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## pathological (Nov 25, 2011)

Not that I'm trying to hijack my own thread, but your hot soak problem could be a weak fuel pump. Sounds like a vapor lock problem we used to have on some cars with carburetors. If your fuel is vaporizing after a drive on a hot summer day, underhood temps would soar after you shut the engine off and airflow under the hood stops. Now if you had a marginal fuel pump it may not be strong enough to deliver enough fuel pressure to push past the vapor lock. Whatever fuel it is delivering would eventually cool the lines and the vapor lock would disappear. It may also be a partially clogged or collapsing fuel filter, though that's unlikely. The fuel pump could also be binding under certain heat conditions and not delivering enough fuel until the incoming fuel cools it down. Just a few thoughts.


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## pathological (Nov 25, 2011)

My car has two cats and I've already checked pricing at RockAuto on line. Prices for replacement cats aren't that bad, but still I hate like hell to just "shot gun" the problem and buy two new converters without being sure that's the problem. By the time I located cheater pipes and bought them, they probably wouldn't be much cheaper than new cats, and then what do I do with the downstream O2 sensors? If I replaced the converters instead of using cheaters this would also keep the Feds happy, for what it's worth.


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## pathological (Nov 25, 2011)

The last time I had the engine apart I replaced the R/H valve cover in case the internal PCV baffles were plugged. I also also replaced the PCV valve, checked the PCV hose for blockage or collapse, the vent crossover hose that runs between the left and right valve covers, and the breather hose that runs from the back of the L/H valve cover to the intake hose which comes from the air filter. I also blew compressed air through these hoses and into the valve covers. There was no evidence of blockage. I think I covered all bases, but?


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## IanH (Feb 11, 2003)

pathological said:


> Not that I'm trying to hijack my own thread, but your hot soak problem could be a weak fuel pump. Sounds like a vapor lock problem we used to have on some cars with carburetors. If your fuel is vaporizing after a drive on a hot summer day, underhood temps would soar after you shut the engine off and airflow under the hood stops. Now if you had a marginal fuel pump it may not be strong enough to deliver enough fuel pressure to push past the vapor lock. Whatever fuel it is delivering would eventually cool the lines and the vapor lock would disappear. It may also be a partially clogged or collapsing fuel filter, though that's unlikely. The fuel pump could also be binding under certain heat conditions and not delivering enough fuel until the incoming fuel cools it down. Just a few thoughts.


sorry to jack the thread....
Thanks for the thoughts, I have a pressure gauge permanently installed to check the fuel pressure and pressure regulator. Its not the typical hot soak because it does not clear with driving a few miles, and pressure is fine, there is also a return line from the pressure regulator to fuel tank to keep lines cool.
Another member actually had the same problem and it was a leak in the diaphragm of the pressure regulator. Mine is not the same, as it doesn't show up on the fuel pressure.
So 1) it doesn't throw a code
2) only fails in summer, after 30 - 60 mins parked. 
3) only goes away after shutdown for a few mins to and hour.
4) is not only the hottest days, not repeatable. 1-3 times a summer.
5) starts and drives but no power, revs up ok, but no pull. accelerates very slowly.


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## IanH (Feb 11, 2003)

pathological said:


> The last time I had the engine apart I replaced the R/H valve cover in case the internal PCV baffles were plugged. I also also replaced the PCV valve, checked the PCV hose for blockage or collapse, the vent crossover hose that runs between the left and right valve covers, and the breather hose that runs from the back of the L/H valve cover to the intake hose which comes from the air filter. I also blew compressed air through these hoses and into the valve covers. There was no evidence of blockage. I think I covered all bases, but?


Agreed.... All bases covered.
If it was mine I would be hoping it was the cats too !!

So I guess you are going to replace the cats next. 

how about running by an exhaust shop and asking how much for temporary test pipes ? I know the wrecker yard wouldn't sell me any used CATS years ago so that's out. Maybe used on the forums here or Craigslist ? Even if they are bad you could gut them.

how-about clogged Oil rings ? Compression would be fine, and Oil gets past compression rings and burns.
This could be a cheap test, try Engine flush, change oil then add additives. See if it improves.
You might have already fixed the main issue, but Sludge and debris in the Oil rings still there.


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## rogoman (Dec 16, 2004)

A good way to test for converter plugging is done with a vacuum gauge. Connect the gauge to a source of intake vacuum on the intake manifold or throttle body. With the engine fully warmed up, the reading at idle should be 18 - 20 InHg. Now bring the revs up to 3,000 RPM, it should be around 21 InHg; if the vacuum reading starts to drop, pressure may be backing up in the exhaust system indicating a possible plugged up CAT.


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## pathological (Nov 25, 2011)

Good idea rogoman. I'll give it a try.


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## pathological (Nov 25, 2011)

Thanks IanH. When I saw that I had good compression I dismissed any ring problem. Never thought about a stuck or clogged oil ring. Sometimes the obvious slips by. I've used various additives but never an engine flush. I'll make a trip to my local AutoZone and see what they have. However, I've got some major work being done at my house right now and that's taking up most of my time. As soon as that's done I'll be back on the Pathfinder. In the mean time keep those ideas coming. Thanks

Vin


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## pathological (Nov 25, 2011)

IanH--I was just thinking about your power loss problem. Suppose it's not a fuel problem but something causing your timing to temporarily go retarded . Also, your car wouldn't be equipped with traction control would it? If that had a problem it could retard timing, turn off spark to some cylinders and cut back fuel, or all of the above. Just a thought

Vin


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## IanH (Feb 11, 2003)

No traction control. Have that on my IS300, pain in the rear.
If it was ign based wouldn't it throw a code ?
I think at this point it could be the swirl valves getting stuck. So when i take it apart for plugs and the throttle plate screws i will look for evidence.
Aluminum Intake expands much more than steel Rod holding the valves and my thinking was the throttle plates on swirl valves get tight in the bores and Jam. There is only a vacuum diaphragm opening these and no electronics to throw a code.


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## pathological (Nov 25, 2011)

Part 1

Checked for plugged cats by checking for vacuum drop at 3000 rpm. No vacuum drop. I have to assume the cats are not plugged. Back to square one. I'll have to try an engine flush additive in the oil. I'm a bit of a purist. Never like to use additives in the oil, but at this point I'll try anything. Although there is no evidence of sludge in the engine (I've had the car for most of its life and change the oil every 2500 miles) I do use 87 octane gas. Maybe this caused enough of a deposit to muck up the oil control rings. It's hard to tell without an engine teardown--ain't gonna happen. 

Part 2

In reference to your power no power problem:

If you think it's sticking, wouldn't it be stuck in the last position it was in before you shut off the engine. That would be idle and the valves would be closed. If they were stuck closed I would think you would have more acceleration than you describe although not the mind numbing power that the 3.5 Pathy is known for. HaHa!! Seriously, if you suspect the power valve of sticking you could mark the position of the crank lever at the vacuum motor at idle and fully open. The next time it happens leave the engine running and check the crank position. Also, you could check the valve for binding by disconnecting it from the vacuum motor and running it through its range with the engine cold and heat soaked. Notice if you feel a difference. 

IMHO you can't check those power valve butterfly screws fast enough. I checked mine and they were not much tighter than finger tight. Remove only one screw at a time from each butterfly so you don't disturb its alignment. Then clean the threads well and use a good thread locker and sock the screws down. No more worries.


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## IanH (Feb 11, 2003)

Part 1
I think if you had a Oil consumption problem from the PCV or Valve cover baffle you would have sucked a lot of Oil into the cylinders causing some coking and deposits in the Oil rings. 
Like you I dislike additives, I suggest using a flush that you add to the Oil, run engine with no load for 20 - 30 mins as suggested and drain. Refill with new Oil and maybe look for an additive to reduce sludge for one Oil change only, and maybe cut it short to 1000 - 1500 miles.

Part 2.
I think it maybe the swirl valves not the power valve that are stuck, I can check the power valves at the operating diaphragm. Last time I investigated this it seemed like the swirl valve operating mechanism was not readily available, as I say it only does this once or so a summer, only once last summer. 

Have you heard if the swirl valve butterflies have the same loose screw problem?


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## pathological (Nov 25, 2011)

OK you got me! I checked my Chilton manual and there is no reference to a swirl valve. What is it and where is it located?

Vin


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## rogoman (Dec 16, 2004)

The engine may have worn valve stem seals which could cause high oil consumption. Here's a "YouTube" video that shows how to test for worn seals:


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## IanH (Feb 11, 2003)

pathological said:


> OK you got me! I checked my Chilton manual and there is no reference to a swirl valve. What is it and where is it located?
> 
> Vin


Yet another 6 butterflies


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## IanH (Feb 11, 2003)

Note:- the power valves are A/T only, no Power valves on M/T


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## lzrj (Feb 23, 2012)

I can not believe no one yet has mentioned the valve covers as being the culprit. The valve covers are the #1 reason for high oil consumption for the 3.5L. I have heard this topic over and over again on other forums. In the valve covers there is passage that gets clogged and the oil ends up getting used by the engine. I suspect that your valve covers are the problem here. From what I understand, the only way to fix is to replace the covers.


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## IanH (Feb 11, 2003)

lzrj said:


> I can not believe no one yet has mentioned the valve covers as being the culprit. The valve covers are the #1 reason for high oil consumption for the 3.5L. I have heard this topic over and over again on other forums. In the valve covers there is passage that gets clogged and the oil ends up getting used by the engine. I suspect that your valve covers are the problem here. From what I understand, the only way to fix is to replace the covers.


OP said he replaced R/H valve cover and PCV valve in post #1


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## lzrj (Feb 23, 2012)

Opps. Yep I missed that. After re-reading it I saw he said the R/H valve cover. My eyes sometimes go faster than my brain. I'm assuming that the the "right hand" cover. Does the left side not have baffles. Its been a while since I read other posts on this matter but someone said both sides could clog. With everything thing else pretty much covered I don't see what else could be causing that much oil to be used.


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## pathological (Nov 25, 2011)

First I want to say thanks to all of you for replying. Next I want to answer all of the recent posts at once.

rogoman--I checked vacuum because my original thought was valve guides or seals. My vacuum is good. Furthermore, I don't think bad valve seals would force oil into the intake, at least not as much as I'm seeing. 

Ianh--Thanks for the photo. I had the intake manifold off and never saw the swirl valves. Either I really dropped the ball here or maybe the 2002 version doesn't have swirl valves. It was probably me.

lzrj--When I replaced the R/H valve cover I cut open the old one and found no sludge or blockage whatsoever. However, I blew compressed air through the breather line and into the L/H valve cover. There was no restriction and at about $200 a pop I didn't want to replace the L/H cover just for the hell of it. There is no sludge in any other part of the engine and the original R/H cover was clean so I am confident this cover is clean as well.


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## IanH (Feb 11, 2003)

I dont think this is blocked CATS so before tearing it down I would run the hose from valve cover to some kind of catch can or large bottle, and then to the PCV valve and see how much Oil is collected. If the blow by is bad you will see the fumes.

So qns. 
1) are the Swirl valve butterflies a problem ?
2) should I vat clean my valve covers when I take it down for power valves?

Normal Oil consumption for me, 1 pt every few K miles.


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## 95HB4x4 (Jun 9, 2008)

@pathological 
I hope you figure out whats causing the oil consumption. I've tried almost everything that you've tried except for changing the valve cover, which I heard only works temporarily. Mine uses a little less oil than yours does but it is still frustrating. 
The only thing I've found that helps a little bit is using 10w40 HM oil in the summer months.


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## pathological (Nov 25, 2011)

When I removed my intake manifold I completely missed the swirl valves. Must have had my head up my a** that day. If the butterflies are held in by the same method used for the power valve butterflies, two screws,I would definitely check them. When you remove the plenum to get to the power valve, take a look inside the pcv hose. If you change the oil regularly and see no evidence of sludge or oil buildup in the hose, I wouldn't worry about pcv valve cover baffle blockage. The baffle setup inside the valve cover looks like a maze. However, there are no tiny channels and it would take a lot of neglecting of oil changes to create enough sludge to plug them. If you have access to compressed air and you want to feel like you did something I would remove the pcv valve and the crossover hose and blow air into the valve covers. 


In reference to IanH's low power problem, while you have the plenums off and if you have access to a vacuum pump, put vacuum to the swirl valve vacuum motor and check for smooth operation and any binding. You could also do the same for the power valve. Also check the butterflies for evidence of rubbing, and check the shaft bushings for binding or excessive play. Just a thought.

Right now I'm using 20W50 oil and so far I've used 1 pt of oil in 1k miles. I don't like using such a heavy oil, especially in the winter but this is just a trial. I may go to 15W40 next and see what happens.


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## rogoman (Dec 16, 2004)

I've been fairly successful with using "Mobil-1 high mileage" synthetic 10W-40 oil in several Nissan engines with a lot of miles on them. There was a modest reduction in oil consumption. The oil does seem to help by reducing seeping of the various seals plus it provides improved lubrication.

Another advantage of using a synthetic motor oil is that the oil change interval can be made at every 14,000 MI instead of the usual 4,000 MI for dino oils. This saves you money.


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## IanH (Feb 11, 2003)

pathological said:


> In reference to IanH's low power problem, while you have the plenums off and if you have access to a vacuum pump, put vacuum to the swirl valve vacuum motor and check for smooth operation and any binding. You could also do the same for the power valve. Also check the butterflies for evidence of rubbing, and check the shaft bushings for binding or excessive play. Just a thought.


That was the plan, I have the gasket set and the plugs ready to go.

I have a large Vacuum pump and can try that, but I expect the main evidence will be rubbing marks on the bore.


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## pathological (Nov 25, 2011)

If I ever get to the bottom of this problem I may go with a synthetic, but the oil consumption is so high right now that I'm afraid a synthetic will run right through it.


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## rogoman (Dec 16, 2004)

pathological said:


> I did a compression check and got 170 to 180 psi across the board. The book says a normal max pressure should be 178 psi, and that's without squirting oil into the cylinders. That tells me I don't have a broken ring or cylinder wear, but I could be wrong. This oil usage didn't happen gradually. Normally the engine would use 1 pt of oil between oil changes (2500 miles). Then suddenly consumption increased to 1 qt/1000 mi. I'm trying to convince myself that it's not a ring problem.


It's possible that an oil ring may have broken. In this case a compression test will still show OK. Examine the spark plugs very carefully to look for any oil fouling.


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## IanH (Feb 11, 2003)

Yes I agree, if its one cylinder this should be enough Oil to show up on the Plug.

If its all cylinders for some reason I don't think you could tell at 1qt /1000based on my experience.
I still think if you did have a PCV or baffle problem that caused excess Oil the Oil rings could be clogged up with coke. Then you fixed the problem but Oil consumption continued worse than normal. 
So did the Oil consumption change after you changed the valve cover and PCV valve? Or no change ?
I have seen some badly coked up Oil rings on some strip downs.


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## jdg (Aug 27, 2009)

O/P:
You didn't by chance change jobs or something along those lines at the same time the oil consumption went up did you? e.g. longer drive to work, more highway miles, etc...

Reason I mention it...('74 Malibu with a SB350...I know, totally different engine, but might help narrow down the cause)
I had a job 6 miles one way, all in town driving, never went over 40mph, also barely used any oil between changes.
Changed jobs, 22 miles, 20 of it on the highway, 60mph+, started using oil like crazy, ~1 qt every 500 miles. Ok, the engine was old, but the theory still stands...narrowing down the cause.


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## pathological (Nov 25, 2011)

The last time I had the top end apart (total of twice) the spark plugs looked very clean. At the time they had about 10,000 miles on them. I haven't made it to the auto parts store to look for a decent engine flush that will free up coked oil rings. Life keeps getting in the way. 

Thanks to jdg for the idea that a change in driving habits may have caused the problem but I'm retired and my driving habits haven't changed.


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## revlee (Oct 15, 2012)

*Same problem: new to forum*

Hi guys, my 05 pathfinder 4.0 just suddenly began using a qt of oil every 200 miles/ HELP! Here's the details: taking a trip to the white mtns in AZ car starting shaking, barely could make top of hills, no smoke,. towed to Payson. Tech ran codes: "intermittent misfire" (but no show of cylinder) and Cat system. Ran additional tests and confirmed that Rt forward Cat was bad. Had both forward Cats replaced with aftermarket ($1200)Made it home, barely, as same problem occurred 10 miles from home. Code this time said misfire #5 cylinder and Cat system functioning below threshold of efficiency. I replaced the #5 coil pak which quickly solved the misfire. Now the code is still for the Cat efficiency and NOW the car is using 1qt of oil every 200 miles or less. This thread seems to have some reasonable information, so I thought I'd register and see if you might have other ideas. No smoke, no drips/leaks, losing hope>>>Where should I go from here? AFter $1200 and 2 cases of oil in 2 weeks, I am at my wits end.


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## pathological (Nov 25, 2011)

WOW 1qt/200 miles. You've got me beat. I thought 1 qt/1000 miles was bad. I am not familiar with the 4.0 liter engine but the first thing I would suspect is a plugged PCV valve or hose. That can pressurize the crankcase, push oil past the rings and get burned in the cylinders. That much oil will definitely raise hell with the cats. A broken ring won't cause you to use that much oil unless you broke the rings in each cylinder. What are the odds? If you're in fact burning that much oil, your spark plugs will be coated with oil residue.

Did you start using that much oil all at once or did the oil usage creep up gradually? What was your oil consumption before the problem started?


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## revlee (Oct 15, 2012)

*05 pathfinder oil consumption*

AFter 115,000, never lost oil; ever; changed it every 5000 miles and it was always to the line; When it died and the cats were diagnosed as the culprit, I had my doubts; especially after the same issues were prevalent; shaking, no power, felt like it was going to stall while doing 60mph, when I was able to go that fast. I still have a 420 code that says my cats are below threshold of efficiency, but did not think that they would have anything to do with that much oil loss. Oil loss began immediately after that, but could have been slightly before, since I changed the oil about 800 miles prior to the shop call.Do you think pulling a 2000 lb trailer through mountains would have anything to do with it? Nissan customer service suggested I have a dealer run a few tests, but I will do anything to not go to the dealer. Going to examine the plug areas for any leakage at all, but now my wifes's 05 murano is also barely showing on the stick after having the oil changed 2000 miles ago...I am ready to trade these in if I don't get to the bottom of it soon. My next move is to check the other 2 Cats and check the pcv valve and O2 sensors. The other note is that the mileage dropped from 20 in town to 15 at the same time; Any other ideas are appreciated.


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## IanH (Feb 11, 2003)

I pull a pop up jayco through the Colorado mountains, overtaking up hill and no issues.
I dont think thats the problem, yes you may use more oil but I don't think it will cause a catastrophic problem. 
Truck weighs what 4000 lbs?, and at full throttle you make same torque and HP. 

So I would test compression, maybe spring for a leakdown tester, or make one.
Then pull intake and look for Oil, pull plugs ditto. check for butterfly screws loose or gone, re-locktight.

replace PCV and hoses. 

I would leave the O2's for now till you are further along, and see if you can get test pipes or replacement pipes to remove the CATS for testing. Only the upstream O2's are important for now.

get a code reader if you dont have one, they are less expensive these days.

my 2cents.


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## pathological (Nov 25, 2011)

I agree with IanH. Replace your PCV and check that the hose is clear. Also check the crossover hose that runs between both valve covers. Pull the spark plugs and check for oil contamination. If it's the PCV system all plugs will show contamination. Using that much oil they should be really fouled. That would account for your loss of power and shaking. 

The cars did not cause the oil problem, they are a result of it. The o2 sensors have nothing to do with oil consumption, so don't bother with them. 

A good compression/leakdown test is good info to have but I don't see it being pertinent to your problem.

If you're going far enough into the engine to get to the plugs and PCV, it makes sense to check the butterfly valve screws and re-secure them. If you lost one or two screws, they could score cylinder walls or break rings but there would have to be an awful lot of damage to cause that much oil useage. Another indication that you are pressurizing the crankcase is oil in the intake hose between the air box and throttle body. While you're in there get some carburetor cleaner and CAREFULLY clean the throttle body. Don't let the carb cleaner get into the throttle position sensor. This won't help with your problem but you're in there anyway. 

P.S. When you go to buy a new PCV, have the old one with you. On my engine thee were two different valves used. Nissan ordered the wrong one for me and told me that the valve I was describing was not used on my car. When I brought them the valve they said it was the kind used on trucks. Go figure!


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## IanH (Feb 11, 2003)

my concern with compression / leakdown is to find out if ring damage is indicated. 

Because of my experience with engines includes broken and gummed up rings I included this as a low cost test to identify the problem or rule it out.

Low compression because of ring leakage does increase Oil consumption because of blow-by and carbon deposits in the Oil ring passages.
my 2 cents.


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## revlee (Oct 15, 2012)

*05 pathfinder oil consumption*

Thanks for the advice IanH and Pathological...Really appreciate it. Because I am back to work now, I don't put a lot of miles on. I replaced the PCV valve, but in the process broke the cheap plastic heater connection at the firewall (dumb on my part). Nissan wanted 280$ for the whole set up, so I used heater hose and a couple plastic T's for $20; works great. Replaced the downstream O2 sensor trying to get the 420 code gone, but haven't driven it far enough to test it out. Old sensor wasn't wet with oil but was pretty dry black powder like heavy fuel...Will be driving 100 or so miles this weekend to check it out. Don't understand why you said the "upstream" o2 should only be considered? Trying to find some time to look deeper and explore some of your ideas. Was wondering if the extreme pressure created towing uphills might have caused a head gasket to crack just enough to only push the oil out while towing and not cause a problem with city driving? Thanks again for the help.


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## revlee (Oct 15, 2012)

*05 pathfinder oil consumption*

After re-reading my original post, I noticed that I failed to say that I had both forward CATs replaced ($1200 aftermarket). Seemed to help for a while, but then I discovered the #5 cylinder coil was bad which solved the misfire,shaking and low power. I am checking oil daily to see if there has been a change.


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## IanH (Feb 11, 2003)

revlee said:


> Don't understand why you said the "upstream" o2 should only be considered? .


What I was trying to say is that the upstream O2 controls the mixture, the down stream only is used for emission monitoring so don't bother fixing this while you are diagnosing what's wrong, its not important at this point.
sorry if I wasn't clear.


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## IanH (Feb 11, 2003)

revlee said:


> Was wondering if the extreme pressure created towing uphills might have caused a head gasket to crack just enough to only push the oil out while towing and not cause a problem with city driving? Thanks again for the help.


Head gasket problems normally leak to the water jacket pushing out coolant and causing overheating, or push coolant into the Sump. There are very few head gasket problems on the forum, and when diagnosed, like one this week, the diagnosis was wrong.

Unless you have overheated the engine I doubt this is the issue.

I don't know that the engine sees any difference in pressures and load at full throttle with or without a load, the only difference might be say 2 mins of full throttle vs 1 minute. These trucks are rated for 5000 towing, so the 2000 load is well within its capability.

I remember the long grade from CA to Las Vegas, full throttle for ever...with AC full on passing everyone !! that was as heavy a load as pulling my 7000 lbs trailer with same vehicle.


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## IanH (Feb 11, 2003)

Re: the question about where the Oil is going.

200 miles to quart is a lot, 750 miles to a quart on a 70's Chevy V8's was kind of normal, plugs and exhaust looked fine, no CATS. Going down the new valve guides, and being burnt.
I don't think you will see much smoke because the CATS are burning it up.

At 75 miles per quart, my only data point of very heavy Oil consumption, going past the new Oil rings on a 1 yr old honda 4 cyl with 15k miles.... 
Smoke looked black like fuel, not blue !!!

Had to take it down again and fit better Oil rings, I couldn't wait for them to bed in. That fixed it to normal 1 pt per Oil change. Also did a second hone, don't know if new compression rings leaking contributed. Yes blown head gasket caused overheating and Coolant in the Oil....Purchased like this with dead engine.

So I hope this helps.


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## revlee (Oct 15, 2012)

*05 pathfinder oil consumption*

thanks so much for the o2 clarification. the "cat low efficiency" code (420) came back for bank 1 even with the new downstream sensor... Guess I should replace the upstream sensor? Engine has never overheated. ever. Almost ready to take it to a pro. Most of my experience was in the late 60's when I could rebuild an engine in a day and was a body man! I can't afford these newer cars especially when the repairs cost more than my house payment...but I gotta drive. Thanks again for your help.


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## IanH (Feb 11, 2003)

did you check to see if you have the missing power valve screws ?

I still think you should do a compression test before taking it anywhere expensive.


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## pathological (Nov 25, 2011)

The Cats get pretty hot. After the oil is burned in them you will probably see the soot you described on the downstream O2 sensor. With my 1 qt/1000 miles oil usage I see soot at my tailpipe. Have you driven enough after replacing the PCV to see if oil consumption has improved? When you changed the PCV did you see if the hose at the PCV and the crossover hose between valve covers were clear?


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## pathological (Nov 25, 2011)

If you get rid of the 420 code by replacing the upstream O2 sensor it may return because your are still drowning the sensor in oil. Question is -- why only one upstream sensor on one bank setting a code and not the upstream sensor on the other side? I would pull both upstream sensors and see if one is coated more than the other. If just the problem sensor is oil soaked then the problem is in that bank of cylinders.


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## revlee (Oct 15, 2012)

*high oil consumption update*

Pvc replace; all hoses are clear. replaced downstream o2 sensor; now have black soot dripping with water in large amounts onto the driveway; it washes off with water hose. Car is running fine, but o2 code returns after 10-15 miles of driving. Ran a tank of fuel; used 1 quart of oil. mpg is only 16.5; normal for vehicle is 19-20 in town. remove oil filler cap and get what I believe is blow by; no loss of coolant. no sign of coolant or oil contamination. Have not done cylinder pressure tests; I am thinking the valve seals are bad, but need to research what type of tools I need to diy or might have to take to dealer, unless someone on the forum can do the job here in NE Phoenix. Appreciate any additional insights. thanks


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## pathological (Nov 25, 2011)

To get to the valve seals you will need to remove the intakes, again, valve covers,and get to the timing chain on the front of the engine. Then remove the cam shafts and valve springs. This is a job for a VERY dedicated DYI'r. Get the shop manual or at the very least a Haynes manual to guide you. Since the problem is apparently not PCV related, (I had my money on that), have you done a compression check? Better than that would be a leakdown check where you put air into the cylinders and see if it holds. This will tell you condition of the rings and valves. The poor MPG's could be caused by the computer adding more fuel to compensate for loss of power. (You've got your foot deeper into the accelerator to compensate for less power). I don't recall, does the engine seem more sluggish than before? Broken rings or scored cylinder walls from debris will do this, bad valve seals won't. A rich fuel mixture will create more condensation and water out the tail pipe. Hope this helped.


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## IanH (Feb 11, 2003)

Guys,
You really need to do a compression test or leak down test so you can rule out major damage. post your results.

You can remove the valve springs and seals one by one using an adapter to fill the cylinder with compressed Air to hold the valve in place, so you don't have to remove the heads. You use a special valve spring compressor to do this. I have done this but not on the VQ engine.

If you cant or don't want to do this, remove the cylinder heads and take them into a machine shop.


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## revlee (Oct 15, 2012)

*high oil consumption update*

Thanks to everyone for the help. My mileage has increased to 18 mpg which is more acceptable. Second tank of gas, again used 2 full quarts of oil. Taking it to ABC Nissan in Phoenix tomorrow to have them figure it out. I just don't have the know how or the tools to take on this big of a project right now. If it turns out to be more than $2500, I will buy a used car and tear this one down and fix it myself; that way I will have plenty of time and won't be pressed for transportation. Will let you know how this turns out.


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## IanH (Feb 11, 2003)

good Luck !!!


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## revlee (Oct 15, 2012)

*high oil consumption update*

okay. Got the call from the Nissan dealer today. He said my engine is shot and needs to be replaced to the tune of $13000. for a long block and $9600 for a short block; two cylinders have bad rings and are pushing oil out. They couldn't tell me which two cylinders and couldn't say for sure if a compression test was done.Give me a break! I guess it's been too long since I've had a real shop work on my cars because I thought they still replaced rings and valves etc..but apparently because too many other issues arose after doing a rebuild, they just go with the new engine. I can somewhat understand this, but have located a guy willing to do a leakdown test and attempt to find the real issue and see if he can fix it. It's still drives fine, but losing a quart/100 miles now. If he can't handle it, I am prepared to take 2-3 months after work to fix it myself. It's just R&R of parts for gosh sakes. pardon my venting; again thanks for your advice. Will let you all know how the new testing comes out; while I shop for another car.


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## jdg (Aug 27, 2009)

Run...run fastly (is that a word?) from that place and pretend they don't exist and never forget that.
Jeezus...$13K? What the hell are they trying to pull? They're just going to replace the whole thing to cover their collective asses and that's about it.
A quicky look on the Google's shows used engines complete for around $3K-$4K and I'd bet you could easily find a wrecked Pathy wherever you're at with a decent motor for wayyy less than $13K, forget the rebuild/refresh and just swap it out.
Past that, a gasket set for a few hundred, set of rings, bearings, etc, for another few hundred each, some machine work, and so on and so on. I can't see reworking that engine, assuming you do as much of the work yourself as you can (obviously can't do machine work at the house...or can you?  ), can't possibly run more than a few thousand $$$, maybe $5K at most (??? Pathfinders aren't my strong suit so I might be way out in the weeds) to get the engine back to practically factory fresh.
amazing...


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## IanH (Feb 11, 2003)

Ive worked on some screwed up engines in the past and recommend you get the leak down down and maybe a compression test for old timers like me.
I assume the Nissan garage did not do and real diagnosis !!!

A set of rings on the pistons and replace any damaged pistons, bunny turn hone the cylinders, and away you go. plastigauge the bearings, replace if necessary. You do not even need to replace the pistons in sets anymore.


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## revlee (Oct 15, 2012)

*high oil consumption update*

okay: Called Nissan dealer back to ask why they didn't do the tests that I asked for. The tech said that the compression of #[email protected] is 155/120. and the other cylinders are 125-130; the compression should be 140-150.Along with the metal from the catalytic converter, causing an off color oil is the reason they said the engine is not worth rebuilding; I found and am negotiating for a used pathy engine with 31k miles and found a young budding mechanic who has the equipment to swap it out. Seems like the best way to go at this point. Car is worth about 7k and I will end up with maybe 4k into it, but hopefully it should last me another 4-5 years which is a hell of a lot cheaper than spending 15-20k for another used one. Thanks IanH and Jdg for your insights...everyone on this forum has been extremely helpful. I sincerely appreciate the help. Blessings.


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## pathological (Nov 25, 2011)

Good choice revlee. When you get your old engine out of the car it might be worth tearing it down to see exactly what the problem was. If you do that, let us know what you find.


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## IanH (Feb 11, 2003)

So they are saying metal from the CAT got into the Engine and Oil ?

I didn't know that the VQ engine had the CAT disintegrating getting into the cylinders problem ????


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## IanH (Feb 11, 2003)

pathological said:


> Good choice revlee. When you get your old engine out of the car it might be worth tearing it down to see exactly what the problem was. If you do that, let us know what you find.


yes please let us know, inquiring minds u-know...


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## revlee (Oct 15, 2012)

*high oil consumption update*

this will be short today because I left my laptop at work and I'm doing this on my android phone. but I am so frustrated, excited, mad, happy, all the same time that I just had to write something to you guys and will provide further update in the next couple of days. before spending 3000 dollars for a used engines I decided to take your advice and get a leak down test and compression test. the results were not at all with the dealer said. all cylinders register between 180 to 189 compression.leakdown test shows from 20 percent for a low to 30 percent for high. I feel like asking the dealership for a brand new car in compensation for the lies misrepresentation they gave me... my mechanic is checking a few other things I said today and tomorrow and again I will keep you advised. Thanks again for all your help


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## revlee (Oct 15, 2012)

*high oil consumption update*

Well, I have narrowed the burning oil down to valve seals. Does anyone know if I can do this without removing the timing chain cover, chain, etc. etc. It looks like I don't have to remove the head and will probably do one bank at a time, unless I have to remove the front of the engine. The manual I have says I have to remove it, but it doesn't seem logical to me. Appreciate any information you might have to share. 

Sent a letter for a refund of my $262 for the tests that were never performed on my car. 
will let you all know how that works out.
Thanks again to IanH and Pathological for their sound wisdom to do the compression and leak down tests.


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## IanH (Feb 11, 2003)

you may have to remove the cams to get access from above so the timing chain / sprockets will have to come off to get them out.
Please bear in mind I have not done this on the VQ.


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## pathological (Nov 25, 2011)

What IanH said. You must remove the cams to get to the valve seals. To remove the cams you have to remove the timing chain which means you have to remove the front cover. How did you decide it was valve seals?


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## revlee (Oct 15, 2012)

*high oil consumption update*

Hi Path.. and IanH; my posting from Nov. 7th gives the details. Nissan customer affairs said to take it to a dealer, which I did. The dealer gave me some bogus data on compression and leak down test, (lies and deception) which I confirmed with an independent mechanic tests. compression and leakdown are great; stopped in a machine shop, who I trust, and they recommended the valve guides and seals be replaced rather than just the seals. If I have to take the heads off I might as well do it right. It is still running very well, but has smoke at start up and it lightens up while driving, but it is still visible and still 2 quarts per tank. Now the debate is, whether I can trade it in for a fair price and save myself the work, go with a rebuilt engine, or should I do the work myself and forget the car payments. Although I am convinced that the valve seals will do the job, I can't find any mechanic willing to do the job. They treat the engine like a "throw away" part so I will have to do it myself. Machine shop will rebuild both heads for $500, so doing it myself really seems to be the cheapest way to go. Sent my letter to Nissan consumer affairs asking for a refund of the $260 for the work that wasn't really done. Next onto the BBB and visa dispute payment process. Again, taking this process slow to see if any other doors open or close. If I Keep on praying and moving it will all come together as it should. Traded in the wife's Murano for a Honda CRV yesterday.Again, thanks for all the help.


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## IanH (Feb 11, 2003)

there is an easy test for valve guide seals. 
IF you can see the smoke.
however thinking about this it would fail if the PCV is still hooked up, and the Oil was being sucked in from there. 

So here is what I know from experience, mainly with older cars.

When you start or lift off the throttle and when u get back on the throttle the engine will smoke because
1) Oil goes down the guides when standing
2) The vacuum sucks in Oil from head and since you are off throttle, it gets sucked in when you open the throttle. down a nice long hill is a great test.

Oil also can also be sucked in from any gallery that has a leak from intake to Oil (This was on several V8's)

With the addition of CATS minor Oil smoke is no longer a good diagnosis tool, but if its as bad as yours it might help.

Let me also say I am a bit unsure of the valve guides and seals being the issue.

I had issues with GM V8's, Chev's had no real seals, and Buick did but seals wore out quickly. No other issues with any other make ever !!!

So go get a catch can, connect to valve cover, re-route the PCV or block it off, give it a try.

Also I guess if you have the heads off all gaskets and seals will be replaced, new valve guide seals and away you go.

I took down more than one engine just to find a similar problem, start at top, work down, you will see Oil on plugs, ie which cylinders, inside intake, where is it coming from, 
For this engine, check for missing butterfly screws, heads off, install new valve guide seals, shop will check for guide wear and clearance ( big bills when you need 16 guides and 15 valves !!! but that was a chevy).

Sorry if this is long and rambling, but i am really concerned this is not your guide seals.


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## IanH (Feb 11, 2003)

Ok a couple more questions.
How many miles on this engine ?
Any overheating in the past ?


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## revlee (Oct 15, 2012)

*high oil consumption update*

I have 115k on the engine and this is the first problem ever...Never, ever has over heated. Today I found a machine shop that will also do the take down. They said we can start with the seals and guides, see if they are bad and work our way down just as you suggested. You can see the oil burning upon start up heavier than when driving down the road. Still 1qt per 100 miles. No oil on the plugs when we did the compression test, but 2 plugs did have more build up than I prefer and they were replaced in June, so I replaced the 2 bad ones. It still makes sense to have the machine shop do the job as I can stop in and inspect as they go and maybe even take some pics or video to see what the real issue is. I will probably need it for my fight with the dealer. Thanks again for the assist.


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## IanH (Feb 11, 2003)

Let us know progress, and the best of luck. My Pathy is at 105K..!!!


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## revlee (Oct 15, 2012)

*high oil consumption update*

well, sent my letter to Nissan for my refund and haven't heard back as yet. Finally found a machine shop that actually will do the job top to bottom. I spoke with the techs, toured their facilities and am satisfied that they know what they are doing. They just called me to say that their tests indicate that the rings are bad; They think it is very unusual for a car with only 115k, and they don't believe it's possible for the CAT to have disintegrated and carried through the valves into the cylinders. They have been rebuilding engines in the valley for over 30 years and came with the "highest" recommendation!. They have an ebay store with excellent reviews. They will call me when they have it apart so I can come look at the damage/symptoms and get a full explanation. Complete teardown and rebuild for 4K. Will verify, take some pics and update as it happens. Should be done latter part of next week. Regards to all for a blessed thanksgiving celebration.


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## IanH (Feb 11, 2003)

revlee,
Any decisions ? Progress ?

Where are you located ?


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## pathological (Nov 25, 2011)

Glad you are finally getting to the bottom of the problem. Way back at the beginning of this thread smj999smj addressed a known ring problem and it sounds like there are updated rings available as a fix. You might have your shop look into this so they can install the latest rings. This might also give you more ammo in your "discussion" with Nissan. 

Rings may also be at the root of my oil usage because I'm noticing that I use more oil if I do highway speeds than driving around town. I'm up to about 2000 miles/qt using Rotella 15w40 oil and one of those "engine repair" formulas, basically the consistency of STP. 

Keep us updated and good luck with Nissan.


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## revlee (Oct 15, 2012)

*high oil consumption update*

Okay, here's the latest on my 05 pathfinder saga. It has been over a week since I dropped it off with Five Star engines in Glendale, AZ. ( I live next door in Phoenix) They are having difficulty finding some parts and had to go to the dealer. Thought I'd have them replace the water pump too since it's a 10 hour job to get to it on a 4.0 L. I spoke with the tech today, here's the story now.
The right side (bank one) has been completely "cooked." Cylinders had to be bored and oversized pistons/rings for replacements. The top of the pistons were badly burned and weakened. Because I told him that I had replaced the CATS, he thought the RT.CAT was plugged, exhaust couldn't escape causing severe temperatures and destruction of the cylinder walls, rings, and pistons.The oil was being burned off the cylinder walls prematurely, destroying any seal that was there. Once the walls were scored and the rings were torn, oil was obviously being pumped out of each cylinder as the top of the pistons were coated with oil. Seems to make sense, but this engine has never indicated an overheating condition according to the temp gauge. I plan to go down on Tuesday after work to get a face to face with the tech to clarify. They said "hopefully" by the end of this week it should be finished.


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## pathological (Nov 25, 2011)

First off it's a no brainer to replace the water pump now, especially if it's never been replaced. Next they feel the R/H CAT was plugged and caused the right bank to be overheated. OK, what caused the CAT to plug up? Most likely oil, which means you had an initial oil problem causing the CAT to plug up.

It sounds like they are only boring the right side and installing oversized pistons and rings rings there. Both sides should be bored and re-ringed. If not, you will have a balance problem, especially since oversized pistons are needed. 

It's interesting that they had to go to Nissan for some parts. If that's the case you might as well just hand them your wallet. For future reference, there is a company called Rock Auto, (rockauto.com). I have dealt with them a lot. Good prices and they have a lot of stuff for just about any car made. It's worth a look. 

Good luck and keep us posted.


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## revlee (Oct 15, 2012)

*high oil consumption update*

I picked up my 05 pathy from 5 star engine in phoenix today. Have only driven it 25 miles, but it is running very well. They stuck to the price quoted (4K to pull and rebuild) and completely remanufactured my engine. All cylinders were bored and new pistons, rings, timing chain, valves, seals, etc. etc. Left side of engine was completely gone. they said the cylinders were nearly square...never seen anything like it. Will drive it this weekend and make sure everything is okay, but I am happy thus far. I am still confused though, in that the codes kept reading "right" bank CAT and misfires, but the left bank was the bad side....the rt CAT was filled with dry black fuel, not oil. I am wondering if the computer is or maybe the mechanic is confusing the sides. Had to pick it up late today, so will have to call the mechanic tomorrow and update this post. Again, I appreciate the discussion and advice. I think I made the right choice as the engine is running great at this point.


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