# 01 Sentra Oil Press light and noise



## Diceman (Jun 8, 2010)

So not too terribly long ago I put a new top end on my Sentra. New head gasket, head bolts, had a valve job as well done on the head. Driving home today the oil pressure light came on and as I was getting off the road it started making noise (possibly the timing chain).

Just to be safe I added some oil (little low, not bad) and it starts and idles fine, but the oil pressure light is still on and the noise is still there if you press on the gas. 

Thoughts?

It is a 01 Sentra with the 1.8 liter engine.


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## Diceman (Jun 8, 2010)

Anyone have any thoughts on this? Gonna drop the oil pan and check the screen. Also pulled the valve cover and the timing chain looks good along with the tensioner.


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## rogoman (Dec 16, 2004)

During the head work, did you have the front timing cover off? If so, there are several O-rings that should have been replaced.


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## Diceman (Jun 8, 2010)

I didn't. When the timing was done I took it to a mechanic. Not sure if he replaced any gaskets. But this is the first time in several thousand miles this has happened.


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## SPEEDO (Jun 9, 2003)

oil pressure switch's do go bad, might change it out, could be a cheap fix.
I wonder if the noise is caused by the knock sensor.. maybe it did not get plugged back in when you had the head work done? a thought anyway...


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## Diceman (Jun 8, 2010)

Agreed. I did check the timing chain. I took off the valve cover and it looks OK as far as I can tell looking down there. The tensioner looks fine chain appears tight. I am going to drop the pan and check the oil pickup screen, Put a new filter and some new oil in it and see what happens.

Any other things to check?


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## Diceman (Jun 8, 2010)

Just so in case anyone encounters what I have....I ended up dropping the oil pan....you have to drop the exhaust (3 bolts and a rubber hanger) and dropped the cross-memeber (4 17mm Bolts and two 14mm for the engine shock mounts). The oil pick-up screen was badly clogged with crap and old oil. I cleaned the oil pan, took the oil pick-up screen off and cleaned that, replaced the oil filter and put new oil and some Lucas Oil (High Mileage engine) and put it all back together....
Oil pressure light is now off and the slapping is gone. The slapping was the timing chain. Because the timing chain uses oil for lubrication, he low oil pressure caused the belt to start slapping.

Hope this helps someone in need one day.....

Till the next issue.......


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## Diceman (Jun 8, 2010)

Well started it today and I still hear a knocking. Cleared the codes...no codes yet....any idea what the knocking could be?


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## smj999smj (Jan 1, 2006)

Hopefully you didn't damage the bearings running them with low oil pressure. I would do two things: confirm proper oil pressure by using a manual test gauge. Next, I would disable a cylinder one at a time. You can do this by unpluging the coil pack at the cylinder you're testing. By doing this, the combustion process doesn't take place in that cylinder and it takes the load off of the piston/rod assy. If, by disabling a cylinder, the "knock" is eliminated, chances are the rod bearing for that cylinder is bad.


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## Diceman (Jun 8, 2010)

Ok, I will do that tonight. The light had just began to flicker when the slapping sound started and I immediately shifted to neutral and shut the car down and coasted to a stop.

Could it be the chain guides?

I will let you know the results of the cylinder test later this evening. Thanks a ton for the advice.


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## jdg (Aug 27, 2009)

Generally speaking....GENERALLY speaking...not correct 100% of the time, but does the job most of the time...

A timing chain noise will be louder while at a steady speed/rpm because if the cams are either accelerating or decelerating, the chain is basically brought up tight against the guides.

A rod bearing knock will get worse when you accelerate and quite possibly go away altogether on deceleration.

A main bearing knock, always there, might be a tad louder on acceleration.

I'm betting on a spun rod bearing.


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## Diceman (Jun 8, 2010)

OK, so it is definitely the timing belt. Started it up, immediately could hear the slapping. Pulled each cylinder coil-pack and the slapping sound stayed when each one was disconnected.


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## jdg (Aug 27, 2009)

Well...so much for generally speaking eh?


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## smj999smj (Jan 1, 2006)

So, I would procede with testing the oil pressure. If the oil pressure is within specs, and considering you already said the pickup screen with clogged up, it's possible that the oil channels to the tensioners are clogged with sludge or debris. This would restrict the flow of oil to the chain tensioner(s) and the chain, or chains, will "slack." There are two ways I know of to correct this. One way, which "sometimes" works, is use an oil backflushing machine (like "Envirolution"). This is the type of service (the "oil flush") that dealerships like to sell even though it usually serves no benefit to people who regularly change their oil (other than lighten their wallet). This is one scenario where it may be worthwhile to have it done. The other way would be to take apart the front of the engine and remove the chain tensioners and the oil filter. Spray carb cleaner into the oil channel ports; you'll see them when you remove the tensioner. Then, use compressed air to blow clear the channel, which will exit out the oil filter adapter. I've learned to do this after doing many KA and GA timing chains! It's a large reason why most of them get noisy and break the "old style" timing guides.


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## Diceman (Jun 8, 2010)

So where can I get a manual guage to test the oil pressure and where would I connect it?


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## Diceman (Jun 8, 2010)

Wouldn't the oil pressure light be on if the pressure was low. I did come on when the screen was clogged, now it is off.


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## jdg (Aug 27, 2009)

Diceman said:


> Wouldn't the oil pressure light be on if the pressure was low. I did come on when the screen was clogged, now it is off.


Assuming the low oil pressure switch was within tolerance, not broken, switched at the correct pressure, etc.etc.etc.etc.
The light doesn't tell you anything about pressure other than when the light is on, the pressure is lower than when the light is not on, and by the time it lights up, it's too late. That's why they call them idiot lights.
And just because the light is out NOW, doesn't mean any damage caused magically reversed itself and now everything is fine.


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## Diceman (Jun 8, 2010)

I agree jdg, I am in no way assuming that it is fixed I am just wondering why it would still be slapping with the oil pressure back in line. I will check the oil pressure manually (where would I hook the gauge up to to manually test it and can the manual test gauge be bought at a place like Pep Boys or Auto Zone?)

If the oil pressure is good and the slapping continues, what would I look to replace at that point?


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## jdg (Aug 27, 2009)

Because, if the timing chain is actually slapping, it's probably not the lack of oil pressure causing the problem.
It's the lack of plastic on the tensioner itself being worn down and not taking up the slack any more.
The tensioner and that little piece of plastic can only extend out so far. Once you get a good groove worn in it, it's only going to move so much, and eventually the chain will stretch just a tad bit more, hence, the slapping.


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## Diceman (Jun 8, 2010)

Any good place to get a tensioner? I guess you have to take the whole from cover (top half) and the bottom half (that covers the crank sprocket) to take the tensioner off?


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## Diceman (Jun 8, 2010)

Guys,
I bought a timing kit, which has new tensioner, guides etc. I took all the bolts off the front of the motor according to the FSM and is there any trick to getting this front cover off? This thing is stuck like a truck..... I did verify all the bolts and brackets are removed as they could be but this thing won't budge.


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## SPEEDO (Jun 9, 2003)

There are bolts that go into the head and some from the oil pan.. are they removed?


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## Diceman (Jun 8, 2010)

Yes, the head ones are removed and the oil pan is out. There were some hidden ones as well, but all are removed.


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## Diceman (Jun 8, 2010)

So I got the front of the motor off, replaced the guides, chain, tensioner and crank sprocket. Put it all back together, STILL makes the same slapping noise....

Anyone help me out here...I am at a loss...


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## rogoman (Dec 16, 2004)

Diceman said:


> So where can I get a manual guage to test the oil pressure and where would I connect it?


You can buy a manual oil pressure gauge kit at most auto parts stores. To connect the gauge, remove the oil pressure switch that's next to the oil filter and install an adapter that fits the block oil port and the other end to the metal tubing that comes with the gauge kit. Look for a 1/8 BSPT to 1/8 NPT adapter to hook up most aftermarket oil pressure gauge kits.


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## Diceman (Jun 8, 2010)

Ok, so finally got the manual oil pressure gauge, hooked it up to where the Oil Sending unit goes and started the car. (Dead cold start) and I was getting about 2 to 4 psi in oil pressure. The Service manual said at 600 RPM, should be at 14. My car idles just at about 1000 after it warms up...

So looking at the manual, I have to take the front cover of the motor off again? Is there anything else to try before that?


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## smj999smj (Jan 1, 2006)

This is the reason I suggested checking the oil pressure in the first place! Oil pressure should be checked with the engine warmed up. The oil is thicker when cold, which will give you a higher pressure reading...not that it matters in this case being that the pressure is that low, cold. Reasons that the oil pressure can be low include bad pump or stuck pressure regulator valve, leaking or clogged oil pickup tube, excessive clearance at the main and/or rod bearings, and low oil level.


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## Diceman (Jun 8, 2010)

What should I check first? Can the regulator be taken off without removing the front cover?

The oil pickup is clean (now)


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## smj999smj (Jan 1, 2006)

You'll have to remove the front cover to get to the regulator. I would replace the entire front cover assy., myself, which would give you a new pump and regulator assy. You can get one from Rockauto.com made by Aisin, which is the OEM supplier of the genuine Nissan part, for $125 + shipping. Since you'll have the pan off, I would check the rod and main bearings.


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## Diceman (Jun 8, 2010)

Sounds good to me. How do you check the rod bearing? Never attempted that before


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## jdg (Aug 27, 2009)

Diceman said:


> How do you check the rod bearing?


There are some really good pictures in most Haynes (or Chilton's, or 'insert company name here') manuals, of good and bad rod bearings.


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## smj999smj (Jan 1, 2006)

Here's a link that shows a good bearing next to a bad bearing:

http://www.jeepforum.com/forum/f11/new-jeep-inline-6-questions-1147675/

General rule, if you can see copper or "layering" in the bearing surface, it's bad. If new bearings are installed, the clearances should be checked using plasti-gauge.


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## Diceman (Jun 8, 2010)

So I am in the process of taking the front cover back off to replace the Oil Pump i got from rockauto. I noticed the timing chain has slipped. I had it lined up when I installed it. Tensioner is on etc. Any reason it would have slipped?


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