# 2001 Pathfinder overheating



## Stew (Feb 18, 2006)

2001 Pathfinder, 61k miles. Couple of weeks ago, heater stopped working and engine was running a liitle cool. I assumed this was the thermostat gone bad, no other problems at the time. Last weekend, engine overheated, spewed a little cooolant. Took it to the shop, had it pressure tested no leaks, shop replaced thermostat and everything was working well. Then today, same thing happend, heater stopped working and a few minutes later engine ran hot. What could cause the thermostat to go bad again? This sounds like classic bad thermostat to me -- any other thoughts? Also I read on another thread that the 2001 Pathfinder has two thermostats -- one is on the top of the engine where the hose goes from the radiator to the engine block, where is the second and what purpose does it serve? 

Thanks.


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## Outkast (Jan 29, 2006)

First look under the water pump for coolant leaking from the weep hole. That would mean the pump is bad. Tstats won't go bad unless it's really old or it got really hot. So look for leaks around all the hoses and also look at the heater core hoses those like to leak alot. If everthing checks out then make sure there is the right ratio of coolant in the system. If there is too much water and not enough coolant then it will overheat also make sure the system was bleed properly cause air likes to get caught in the heater core.


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## smassey321 (May 27, 2005)

I recently changed my coolant and before I got all the air out, I had no heat. The bleed valve for the heater hoses is at the back of the engine up top. It is a tube with a black rubber plug on the end of it. There is a sticker behind it on the firewall that says "never open when hot". On a slightly warm engine (driven an hour ago), pull the plug off and run the engine until coolant comes out. You should rev the engine a little to force some air out.


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## Stew (Feb 18, 2006)

So this has been a really frustrating problem for me. My pathfinder is still overheating. But it does so intermittantly. Please allow me to tell y'all the whole story and see if you have any suggestions. 

I had my radiator flushed at 60K miles. Shortly thereafter, the heat stopped working. I thought the thermostat was bad and put off getting it replaced for a couple of weeks. In the meantime, my car overheated while driving. THus I immediately tood it to the shop to have it checked out. They pressured tested the cooling system. Found no leaks and replaced the thermostat. I got the car back and everything worked great for about two days. Then it overheated again. Took it back. They bled the system again. Again, I got it back and everything worked great for a couple of days, then it overheated again. Then I took it to the dealer. They replaced some thing the guy kept calling a "shuttle cock" (its some gasket somewhere, I think) and replaced the drive belts (which needed to be done anyway). Got the car back, and in a couple of days overheated again. Took it back to the dealer, they hooked it up to pressure and left it over night. Said they found a couple of small leaks and clamped them. I got the car back, and in a couple of days it overheated again. I've been obessively checking the coolant levels before each drive. Its not leaking as far as I can tell. I can't figure out whats going on and two shops so far haven't done so well either. Any thoughts?

Appreciate your help. 
Stew


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## Xeno (Oct 5, 2005)

First thing I would do is replace the radiator cap and overflow tank cap with new ones from the dealer. Because they are pressure regulated and could be worn or the wrong ones. 
Second, look down your radiator fill hole (when cooled) and see if the radiator cores are corroded and or plugged.
Is your overflow tank still connected to your radiator?


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## smassey321 (May 27, 2005)

What are the conditions when it overheats? In traffic or on the highway? What is the temp outside?


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## lewisnc100 (Apr 25, 2003)

Stew, I remember posts in the past about the 2001 and newer Pathfinders having 2 thermostats. The second one is called a "water control valve" but its a thermostat. Not sure what function it serves, but worth asking the dealership if it could cause overheating.


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## smassey321 (May 27, 2005)

The water control valve is in the coolant pipe at the back of the engine. It looks like a traditional thermostat. It goes in from the top and is held in with a couple of bolts. It appears to be a little over on the drivers side.


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## Shortstack (Oct 17, 2005)

*Ideas*

I have a couple of ideas that have not been mentioned. 

If it is over heating in traffic it could be an air flow problem. There could be a problem with the fan not pulling enough air through the radiator to cool the coolant.

I have heard of a flush breaking something loose inside and causing the debris to lodge in an opening and sometimes it blocks the coolant flow and sometimes it doesn't. Similar to debris in a home sewer line.

Lastly, I have a friend who had this problem recently and he spent alot of time and money, going as far as replacing the head gaskets, fan clutch, numerous thermostats, etc... He took it to numerous mechanics who could not find the problem either. Only to find out when it was too late that the oil pump was blocked and causing the motor to overheat.


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## Stew (Feb 18, 2006)

So I've mentioned this "water control valve" to the mechanic, who says that this model doesn't have one? However, many people have mentioned this on this board and in other posts. Does anyone have a diagram or picture they could send me through email so I can point this thing out? It sounds like this may be the problem...I appreciate all the input..

Thanks.


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## lewisnc100 (Apr 25, 2003)

Any chance you have a Haynes Manual, if you do there are several pictures on pages 3-4 and 3-5. Plus a very detailed description of the 3.5L setup with a thermostat and a water control valve on page 3-4.

"On 3.5L V6 engines, there is a secondary thermostat (called the water control valve) that can be accessed only after removal of the intake manifold"


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## Stew (Feb 18, 2006)

I don't have a Haynes manual, but I'll see if I can track one down. Thanks.


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## Elias Brache (Jul 17, 2006)

Hi everybody.
Today my recently bought 01 pathfinder overheated, i checked the oil and looks like the previous owner havent changed in a while (could that be?) , i stopped and suddenly with the engine running it started to cool by itself. Ill change the oil right away but i dont think thats the problem, coolant looks ok just maybe to much because is over the limit mark (because of the overheating?), fan is working, only thing i dont like is a shhhhhhhhh kind of whistling (windy) sound that the engine makes. any ideas?
Thanks
Elias


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## KLL (Dec 2, 2005)

lewisnc100 said:


> Stew, I remember posts in the past about the 2001 and newer Pathfinders having 2 thermostats. The second one is called a "water control valve" but its a thermostat. Not sure what function it serves, but worth asking the dealership if it could cause overheating.


in BMW water control valve is there to adjust the temperature of cabin heater. for example for left and right sides there are two water control valves to adjust different temperatures. these are definitely part of cooling system. they adjust the amount of hot water passing throught them to cabin heaters. by the way if thermostate is new and it is correct one interms of opening temperature, your fan clutch may be broken. as you observe when engine is cold fan do not turn. when it gets hot it start to blow air to engine. and (i am not sure for pathy if there is a plastic propeller attached to fan to pump water through ) water pump can be broken. these are major intermittent overheating problems for these type of cooling systems.

if you replaced the coolant and/or serviced the system there can be a water lock because of air pockets inside hoses. you need to bleed the system by raising the front of car while engine is running and heater is on heating position on AUTO setting with defrost.


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## smassey321 (May 27, 2005)

KLL said:


> if you replaced the coolant and/or serviced the system there can be a water lock because of air pockets inside hoses. you need to bleed the system by raising the front of car while engine is running and heater is on heating position on AUTO setting with defrost.


To bleed air from an 01 and up simply open the bleed valve at the rear of the engine. It is a 3/8" tube sticking up with a black rubber plug on the end of it. There is a sticker on the firewall behind it that says "do not open when hot"


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## robinhood58 (Aug 3, 2006)

Hi Stew,

Did you have resolve the hoverheating problem since his post?

Hi have same problem with my path...


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## Dflosrt4 (Dec 25, 2005)

Hey guys i have seen some similar problems with what you guys explained. I am a tech at
a nissan dealer. anyways to me it sounds as if you have air still traped in the system. There is a tool which pulls a vacuum on the system using the venturi effect. That is the only way i found to get air out of the system. Something like that actually happened to a guy at my work. He flushed the cooling system and didnt bleed the system using that tool. The tech thought he got all the air out but really didnt. When he did use the tool we found that the system would not hold a high enough vacuum. It only held about 10hg of vacuum which it usually holds at least 15+. We also found that the radiator was clogged. We replaced the radiator and it was fine. The tech actually replaced the thermisat thinking that was the problem. I bought my tool from a matco dealer. OUr shop has one because there is a bulletin on traped air in the cooling system which this tool is one of the only ways of emlinating it. Hope this helps.


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## s32bn1bge1 (Oct 15, 2006)

Have you checked for a plugged up radiator??? The lower hose will collapse if you put some throttle to it. If this is the problem, GET THE SUBSTANCE ANALYSED!! it might be Aluminum Oxide. If it is there are at least two more of us that are having the same problem, and Nissan is ignoring the problem


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## munnyn1 (Jan 10, 2008)

*2001 pathfinder overheating (3.5 LE)*

I have intermittent overheating. When going up hills the temp shoots into the red and once on the downhill it comes down to normal.

I cleaned the radiator system and have 'burped' it several times.


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## munnyn1 (Jan 10, 2008)

I have the overheating problem as well. any solutions?

[email protected]


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## ncharlesn (Jun 12, 2008)

I have a 02 Pathfinder doing the same thing. Just flushed the coolant, changed lower thermostat and now it's overheating worse. The overheat issue before was only while towing on an average summer day (85F) with the A/C on (~75F). Now it overheats w/o towing anything (same ambient and a/c settings). Thought about trapped air, but it was overheating before this. I swapped the radiator cap around 90k and I have 105k on it now. I'm just about to throw a fan clutch at it, but I'm at a loss. Swapping the upper stat is a heck of a job (I think the dealer wants 5hrs labor), but I can't imagine them having any better idea unless it's a common problem. Anybody with success out there??


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## munnyn1 (Jan 10, 2008)

I flushed it, cleaned, talked dirty to it, but nothing so later today I will be changing the radiator. appparently the radiator gets plugged up easily and you can not get it out.


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## shawn 81 (Jun 14, 2008)

*Pathfinder overheating*

03 Pathfinder overheating on warm days or while under strain. I have replaced the fan clutch, the front thermo, the belts, the fluid to no avail. I bought an extended warrenty when I puchased the vehicle. However, Nissan states that the coolant system may be clogged with "stop-leak" (not covered under the warrenty) and will probably need the the entire system replaced. Problem is the truck has NEVER had any "stop-leak" added for any reason..They are telling me that it may cost up to $7500.00 for repair. They cannot tell me for sure that it is "stop-leak" until the engine is torn apart, but I am liable for the entire bill if is "stop-leak". After much whining and complaining the Service Director became involved and has decided to send the radiator off for service because if i turn on my heater the engine cools down (indicating coolant flow though the block but not the radiator) Hopefully this fixes the problem. If there are any others out there who have had this problem please let me know how it was resolved at smbenders at yahoo dot com. I will post to let everyone know what happens with mine.


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## shawn 81 (Jun 14, 2008)

*How to fix the overheating problem...*

Per the above, I was pretty frustrated with it all. Radiator flush will probably not work, so don't waste yor time. From what I can tell these trucks end up with a clogged radiator at abpout 100,000 miles. Take your radiator to a radiator shop and have it "rodded-out" or replace it. I am going on a 1400 mile trip this weekend with this truck, and if you don't heare from me, consider the problem solved..


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## ncharlesn (Jun 12, 2008)

*Solved overheating 02 Pfinder*

Yep, don't bother with the flush. Tried it. The cleaner took out the seals on the radiator top/bottom caps and was leaking all over. Got a radiator from 800radiator overnighted, tossed it in in about 2hrs and viola no more issues.

As someone else found earlier, the old radiator had white scaling on the inside. Some sort of oxidation...


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## 2milehi (Mar 4, 2008)

^^^^ Comes from using tap water mixed with anti-freeze. ALWAYS use distilled water.


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## 2bizze (Jan 25, 2005)

*2001 Nissan Pathfinder overheating*

Did you ever figure out what the problem was that was causing your over heating? I have the same intermittent overheating problem with a 2001 Pathfinder. I can go days or weeks without it over heating then go three day in a row. 

When it does over heat its absolutly quick maybe 45 seconds alsmt simular to a thrown fan belt. Whats strange is you can shut it off and restart it, sometimes it will immediately cool off and other times it wont. Already changed both thermostats. Strangest thing is my laser temp gun doesn't show it being that hot, and that has got me thinking that somehow, something is on occasion blocking the flow from the radiator.

If I am correct many engines have had head gaskets changed for no reason, though by the time the engine has been overheated many times the heads may no be warped and the head gaskets may get blown then but only as a result of the severe overheating.

We checked the radiator with an exhaust gas analyzer and found it to be clear with no hint of exhaust in the radiator so we don't believe its a blown head gasket.

With my current thought being something is floating around inside of one of the hoses and occasionally is blocking the intake to the forward thermostat. In the morning I am going to pull all the main hoses and forward thermostat and run a hose to the block to try to flush everything out.

Thanks for any idea's and help you guys can give me, let me know if you have found the cause and fix for this.

Joe


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## 2bizze (Jan 25, 2005)

*Desperate need of ideas before I scap the whole thing!!*

I still don't havve a clue other than I am pissed about the whole situation. I have the cylinder heads off. Found severe detonation damage on the #1 piston and on the cylinder head for the # 1 cylinder only. The damage is on the upper and lower portions of both the head and the cylinder. Looks like someone took a claw ahmmer to it.

Absolutely no damage to the center of either one. The damage is about one inch tall on both the upper side and lower side only.

Obviousely something is making this cylinder run severly lean at times yet not on any other cylinder.

I REALLY NEED SOME HELP HERE AS THIS IS EVEN STUMPING MY LOCAL EXPERT NISSAN MECHANIC. He has already consulted with his buddies at two local Nissan dealer without any success.


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## 2milehi (Mar 4, 2008)

2bizze said:


> I still don't havve a clue other than I am pissed about the whole situation. I have the cylinder heads off. Found severe detonation damage on the #1 piston and on the cylinder head for the # 1 cylinder only. The damage is on the upper and lower portions of both the head and the cylinder. Looks like someone took a claw ahmmer to it.
> 
> Absolutely no damage to the center of either one. The damage is about one inch tall on both the upper side and lower side only.
> 
> ...


Please post a pic of the damage


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## 2bizze (Jan 25, 2005)

I am having trouble getting a picture to post. What it looks like is someone used the claws of a claw hammer to beat the crap out of the flat surfaces on the cylinder head. This is on both flat surfaces above and below the valves. This is the same mating surface as the head gasket gaskets sits on that extends to the cylinder area. The cylinder heads surface is perfectly flat with no warpage of the head. The only damage is where these areas described is beat up and I'm sure the detonation is what caused the head gasket to fail.

Inside the dished area of the cylinder head there is no damage, nor is there any damage to any of the valves.

So now my question is why did this cylkinder run lean, and not the others? 

Why didn't the Knock sensor retard the timing? Does the knock sensor need to sense detonation in all cylinders before it retards the timing? Could the knock sensor be bad as well?


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## 2bizze (Jan 25, 2005)

I attached a picture of the detoantion on our race site. Its not a very good picture but you will get the general idea. 

www.shaneharding.com/albums/album_image/3888274/4191647.htm


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## Quick69GTO (Jun 8, 2008)

Could have been a clogged or weak injector, an intake leak, a low level head gasket leak allowing small amounts of coolant into the combustion chamber,..........anyway, the damage is done.
I would just forget about that engine and drop one from a salvage yard in it.


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## IanH (Feb 11, 2003)

What about the loose screws from the butterfly valves !!!


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## 2bizze (Jan 25, 2005)

IanH said:


> What about the loose screws from the butterfly valves !!!


????? Are you suggestion a screw came loose and worked its way into the cylinder? If you are I'm positve thats not the case as there is no damage anywhere on the piston or cylinder head except the areas described.

A screw bouncing around in there would have covered the whole piston with those marks.


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## IanH (Feb 11, 2003)

Yes, from the power valves, this is a known problem.
Ok just wondered if this was the cause of the damage.


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## 2milehi (Mar 4, 2008)

+1 with a poor flowing injector


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## 2bizze (Jan 25, 2005)

*HELP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!*

Replaced both cylinder head gaskets, no warpage found on either head. Replaced the water pump. Replaced both and thermostats again. Flushed and checked each fuel injector for flow. 

It still has intermittant overheating. Two weeks after the work was done it overheated, then it hasn't over heated in the past week. It was not low on fluid after the overheat. Unfortunately didn't get to check to see if was filling up the overflow bottle while it was happening.


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## Meadow (Nov 29, 2008)

*Please Help!! Overheating again!*

Hi,

I have a 2001 Nissan Pathfinder and about a month or so ago I noticed the temperature was rising. I am a girl who doesn't know much about cars so I pulled into the nearest gas station and asked for help. After figuring out it needed coolant, I bought the coolant and he filled it for me. 
About a week later I was on my way to school and it started to overheat again but this time I didn't notice anything until smoke was pouring out from the hood. At this point there wasn't much I could do since it was 6am, so I pulled over, turned off the engine and sat for a bit then drove to school. On my way home I stopped at a nearby Jiffylube and they topped everything off. I took it into the mechanic and he checked everything - pressure tests, let it run for awhile and ofcourse it didn't overheat. He thought it was the radiator but apparently not and basically he didn't know what was wrong because it wasn't overheating for him. Then just today it started chugging like it was running out of gas. It's so frusterating because I work full time and go to school full time - I NEED a car, but I can't afford multiple repairs. I don't know what I should do, or what is wrong with it. Can anyone help??? Please?


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## 2bizze (Jan 25, 2005)

I can tell you this an exremely expensive repair. A dealer will charge you 22 hours of labor per side to change the head gaskets. Depending on which dealer you take this to this will amount up to $3300.00 per cylinder head and youhave two cylinder heads.

I cannot suggest this enough! GO TO YOUR NISSAN DEALER AND TRADE THIS LEMON IN! 

This engine without question has the most difficult cylinder head gasket replacement on any engine I have seen in my life.

A cheaper option to replacing the cylinder head gaskets is to replace the engine with a used engine from a wrecking yard. Look at car-parts dot com for a used engine Car-Part.com--Used Auto Parts Market I could have bought a used engine with only 8,000 miles for $2,000.00 and I would have been better off.

I regret not trading this in or replacing the engine myself as the engine is still overheating on random ocassions depite me spending $4,000.00 in repairs, over 40 hours on the phone, countless hours searching the internet to no avail, and no assistance from nissan tech to solve this problem.

All I can say is good luck, doing anything other than a trade-in will deplete your bank account.

By the way I am a three time Nascar mechanic of the year, I am very experinced with working on cars. This vehicle has to be one of the most frustrating I have ever worked on. I rarely if ever pay anyone to work on my cars. After changing many parts, radiator both thermostats water pump, heat sensors. I ran out of time to work on it and had a local independent dealer who specializes in Nissan's work on it. He ran into the same problems I did and was unable to get it to overheat except on a random basis. By the time he was done he had the Pathfinder for 6 weeks.

You can probably sense my frusration with this Patfinder. SORRY TO SAY THIS BUT TRADING IT IN IS YOUR BEST AND ONLY REAL OPTION.


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## Meadow (Nov 29, 2008)

Thank you very much for your response, I appreciate the advice. There is no way I could afford this much in repairs. I was not expecting it to amount to this much. After reading some other threads it seems this is a common problem with Nissans. I go to a local mechanic who usually doesn't charge me for labor, so I am going to take it in - I will tell him what you told me and figure out what to do from there. 

You wouldn't happen to know if there is any temporary fix so I will have a way to and from work and school in the meantime???


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## 2bizze (Jan 25, 2005)

I don't reccomend it but HEAD GASKET sealer might work for a while in this situation. The better the old anti freeze is flushed out before hand will increase your chances of it working. The old anti freeze fluid needs to be flushed out with water three times or more.


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## IanH (Feb 11, 2003)

did they check to see if you are losing coolant from some where else, like a water pump or hose ? do you check the coolant bottle level regularly ? 
thermostat opening correctly ?
When your mechanic looks at it ask what checks can be done to determine if any damage has been done by the over heating. 
Check the coolant for acidity ? Compression test ? 
I have not had any issues, and it doesn't seem that the forum is over run with this type of problem.

Good luck....


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## 2bizze (Jan 25, 2005)

IAN you are correct in looking for the obvious. This problems appears to be confined to the 2001 year only. With your Pathfinder being a 2003 you will not likely have a problem. The the overheating with this engine has been posted on a few different message boards all with the same problem. Its expensive to troubleshoot by throwing parts at the vehicle which is what most including myself have done. 

In hindsite changing the water pump was stupid as the water pump either works or doesn't work the only way it fails is to start leaking of which once they start leaking they always will continue to leak and its very obvious. 

This engine has two thermostats. Changing both doesn't help. By the way you have to pull off the intake manifold to get to the 2nd thermostat.

Changing the radiator doesn't fix the problem either. 

The only way to know if any overheating caused internal damage is to pull the cylinder heads which means you are looking at a $4,000.00 repair bill if the heads are not warped. If they are then its even higher.

By the way all of the maintenance manuals tell you that in order to replace the cylinder head gasket you MUST pull the engine from the vehicle. Once agan in hindsite knowing what I do now if I am going to go through the effort to pull the motor it easier and cheaper to put a used motor from a 2002 or 2003 in.

You have know idea how complicated a job this is the pull the cylinder head.

You have to remove all four camshafts and they are all indvidually shimmed just to reach the head bolts.

The timing chain cover is an amazingly complicated piece you would be shocked to see all the pieces involved when its taken apart. 

While it may not seem there is a huge problem with this problem there is a signifiacant number them as the local dealers have been selling a abnormally high number of head gaskets for this year vehicle.

Checking the overflow regularly? This isn't something that needs to be checked more than once or twice a year. If the service station topped of the fluid in the past month thats more than sufficient.

Like I said before and I hate to say it, the best solution is to trade it in and let the dealer take the hit on it when they sell it to someone else.


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## IanH (Feb 11, 2003)

thanks for the prompt reply, pleased to know my 3.5 doesn't have this problem, just an appitite for swallowing screws !!
So you saying that this is a confirmed head gasket problem that's only with the 2001 engine ? 
or are you saying this didn't fix it and the cause is unknown ?

I was suggesting checking the fluid level in case this was caused by a leak, not as a regular maintance item.
As for the complexity this is a V6 DOHC and the shims are the same as the GA and other DOHC's, Toyota's Jaguars etc. I have found that they don't need adjusting over time, but that just my personal experience. And no i haven't taken my 3.5 VQ apart yet.


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## 2bizze (Jan 25, 2005)

As far as I can tell its only the 2001. Maybe it will take equivelent milage on a 2002 or 2003 to duplicate not sure about that. Yes that is correct I cnnot say that this is a confirmed fix. The thing overheated once two weeks after the head gasket were changed and hasn't overheated since.

The shimming of the cams and the complexity of it equates to a very expensive repair job when it comes to replacing both cylinder head gaskets as there is no easy way to determine which side is the defect on.

Prior to replacing the head gaskets, my factory trained Nissan mechanic who has only worked Nissans the last 30 years assured me it wasn't a head gasket as he was unable to duplicate any overheating despite driving it for 10 days. He was unable to get any exhaust readings from inside the radiator. In took him a couple more weeks of playing with it before he picked up exhaust readings in the radiator.

I will tell you this when it does decide to overheat, it goes from normal reading to overheating in less than 60 seconds.


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## IanH (Feb 11, 2003)

2bizze said:


> As far as I can tell its only the 2001. Maybe it will take equivalent mileage on a 2002 or 2003 to duplicate not sure about that. Yes that is correct I cannot say that this is a confirmed fix.
> 
> I will tell you this when it does decide to overheat, it goes from normal reading to overheating in less than 60 seconds.


How many miles ?

Damm that's fast...

Was the radiator cap replaced ?

Since you did get a positive for exhaust, but took a long time suggests a small leak or crack...


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## Silver & Black (Mar 28, 2008)

Has anyone gotten to the bottom of this overheating problem? My 99.5 has the same problem when going uphill, using the A/C on a hot day, and at random times. So will a new radiator solve the problem?


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## 2bizze (Jan 25, 2005)

Not likely unless your engine is a 3.3 liter. Is your engine a 3.5 liter or a 3.3 liter? I have not heard of this problem affecting the older 3.3 liter engines.


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## Silver & Black (Mar 28, 2008)

My engine is a 3.3 liter. Its a 99.5 I believe its the one with the silver body panels and bumpers I believe a SE model. Its a 99 that has the 00 and above bumpers head and taillights.


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## 2bizze (Jan 25, 2005)

I have no experience at all with the 3.3 liter so I have no idea if the problems are simular or not.


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## robinhood58 (Aug 3, 2006)

Hi 2bizze,

did you never resolve the overheat issue?


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## 2bizze (Jan 25, 2005)

No it still overheats on a random basis since replacing the head gaskets. I am going to trade it in in the next couple of weeks.


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## Clutchdog (Feb 18, 2009)

Hi,

I have a 2001 with the random overheats as well. Changed the thermostat as well. Had them check for exhaust leak using that chemical test they do. But still overheats. So i took it to them with the air in the system idea and they used a vacuum tool on the air bleed. Still overheated. 

Taking things into my own hands. I figured that you can only get so much fluid in there to replace any air that comes out. Because when you rev the engine it blows and sucks back in. I yesterday hooked up a clean empty plastic bottle and clear hose to the air bleed at the back of the engine. Added about 1/4 coolant and hung it in the engine bay with the hood open like an i.v. bag. (poked a hole in it to allow breathing) Figuring that any air that comes out will only get replaced by coolant going back in. I ran if for about an hour and watched all the little air bubbles slowly make their way out of the system. There was ALOT of air at first. I couldn't believe how much air came out. I figure that it must be collecting around the water pump inpeller and stopping any flow. Just like it does in basement sump pumps and boat props. Wish me luck.


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## 2bizze (Jan 25, 2005)

Clutchdog, soory to tell you this but is will continue to overheat, the frustrating thing is its only on a random basis. 

A sure sign you have the persistant overheating problemn is that you can go from normal operating temperature to overheating in about 30 seconds.

Good luck as your going to need it. Great idea on using an old bottle as an IV bag to bleed the air though.


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## Clutchdog (Feb 18, 2009)

2bizze said:


> Clutchdog, soory to tell you this but is will continue to overheat, the frustrating thing is its only on a random basis.
> 
> A sure sign you have the persistant overheating problemn is that you can go from normal operating temperature to overheating in about 30 seconds.
> 
> Good luck as your going to need it. Great idea on using an old bottle as an IV bag to bleed the air though.


You might be right. 

The only thing that was consistant about it is that all of the three times that it did overheat, it was under load. (up a hill or maintaining high speed)The reason that i think it has to be air in the pump is because you can't just have a random chunk of something going around randomly blocking. Just can't happen. If it blocked once, then it would stay blocked. Air at least could get sucked into a mechanical pump and stop any flow. Once air is introduced there just isn't enough air pressure to push water. You shut it off...the air rises back into pockets and the pump is again exposed to fluid. Hence the ability to cool again. once under load, the bubbles are agitated and flow in the system eventually getting caught up in the water pump. Even if i am right, i still haven't addressed the reason for the air getting in the system to begin with as it never had an issue prior to the first overheat. Its too bad because i enjoy the vehicle. Its alot smoother of a ride than my TJ. And alot more room.


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## 2bizze (Jan 25, 2005)

Going up a hill or even a slight rise in the road seems to be a common issue.


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## Clutchdog (Feb 18, 2009)

so far so good.


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## laopadak (Jun 2, 2009)

*Similar overheating problems on 04 LE*

My 04 recently started overheating (first time ever, just once on a hot day). Talked to my mechanic and we felt it was the thermostat. Since the car has 98K miles we decided to:

Flush radiator
Oil & filter
drive belts
transmission fluid
Thermostat & Gasket
New plugs

Got the car back this past Tuesday and I drove regularly for 2 days. On Thursday's commute home, I was stuck in traffic gridlock w/ AC turned on and temp didn't rise, got thru the traffic and returned to normal driving conditions (40-50mph) and quickly noticed the temp raise to almost maximum, luckily I was only 1/2 mile from home.

Got home and checked for leaks or anything wierd, nothing. Car's currently at my mechanic's shop awaiting instruction/trouble-shooting.
___________________________________________________________

The car does not leak one drop of coolant. I've asked my mechanic to check for any types of leaks, he can't find any.

Does anyone think it could be that the coolant wasn't properly bleed?? 

One thing we're thinking is that the main fan doesn't switch speeds when the car's sitting idle w/ AC on for a long period of time. (Car currently overheats when doing this)

I spoke to the local dealer and asked about some sort of fan switch/relay or coupler. Parts guy says the coupler is what switches the fan speed from low to high when AC is on or when operating temp gets on the high side.

Cost of coupler is around $180. Does anyone think this could be the problem? 

Thanks in advance for any advice/experience.

Peck


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## 2bizze (Jan 25, 2005)

Have a low test done on the radiator first these radiators are VERY prone to plugging internally. As it turns out my fairly new radiator with only 20,000 miles was completely plugged by the exhaust gasses from the leaking head gasket corroding the internals of the radiator. SO I can now say my overheating problem is finnaly fixed.

Its ony $180.00 for a new radiator so I would suggest the flow test or just replace it. A bad fan coupler will not cause it to overheat at highway speeds.


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## laopadak (Jun 2, 2009)

^^^Thx for the advice 2bizze


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## Clutchdog (Feb 18, 2009)

Well, it happened again. Took a really long time. So i bought a coolant pressure tester. See where that gets me. Must be a really small leak. Either way, i am selling the piece of junk. Never buy another nissan.


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## 2bizze (Jan 25, 2005)

Clutchdog, I have a hunch the problem could be a crack in the block. On another thread the dealer found a cracked block to be the problem, though the dealer said the owner caused it to crack by continuing to drive with it overheating. The owner denied doing this.


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## Clutchdog (Feb 18, 2009)

Possible. But the fact that the original issue has not been found that caused my original overheat, I would say probabally not the same cause on mine. I also have had a chemical check where they test for exhaust gasses in the coolant. I would think a cracked block would show up in that check. Maybe not though. I just haven't had time to do the pressure test yet.


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## 2bizze (Jan 25, 2005)

Clutchdog your problem is similar to many others as there is nor obvious problem as to why its overheating. A cracked block may be the truce cause of why its overheating. I think Nissan used it as an excuse to blame the driver for why the engine had a cracked block. In the end Nissan charged this guy for a used mtor but installed it for free.


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## Aptera2h (Apr 20, 2011)

*Nissan Pathfinder 2001 overheating*

I had the same issue with my Pathfinder, he was fine if the truck was running by itself but then one day I was pulling a trailer and the temperature started going slightly up and then more and more close to the last line of the gauge and I stopped the AC and ran the heat to full and saw the temperature going back down in a hurry.

SO my guest was a bad termostat so I took it to the Christian Brother Automotive, they keep the car all day and could not figure what it was, at least they did not charge me. But if I was pulling a trailer - even an empty one, the truck temp would shoot back up. I noticed as the days were getting hotter, that even by itself the truck would start overheating when climbing hills up and down, since it was going to get hotter and I did not want to go to another shop for them to try to figure it out, so I went to the dealer and they determine it was an obstruction in the radiator, I guess after 160,000 miles you should expect that, $1000 less in my pocket but apparently that should fix it, willpost if that does not


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## 2bizze (Jan 25, 2005)

If the radiator doesn't fix it I wouldn't spend one penny more to try and fix this engine. Go to Car-Part.com--Used Auto Parts Market and buy a used low milage engine and replace the entire engine. You should be able to buy and engine and have it installed for around $2500.00

This will be much cheaper than replacing both cylinder head gaskets. Changing the head gaskets is an expensive job on this engine. You can easily spend $4000.00 dollars to both gaskets ans then you still have an engine with 160,000 miles on it and may still have the problem if the cylinder head is cracked.

Good luck.


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## portiz (Sep 25, 2014)

*Nissan PathFinder Over Heating*

My husband had the same issue with is 2001 Nissan, PathFinder running hot. It actually blew the entire top portion off the radiator just as he was approaching home. He called a mechanic (Harry Cain) who came to our home. He has been a mechanic for 30+ years. He replaced the following parts. I am including the price the mechanic paid at O'Reilly Auto Parts. Taxes not included:

Radiator - $130
Water pump - $51.00 
Thermostat w/gasket - 19.99

After replacing those parts fully, to include the coolant, he ran the engine until the rough sound subsided after approximately 20 minutes. He said running the engine caused tension to buildup on the inner chains that was loosed during replacement of the water pump. After that we noticed the gauge inside the vehicle that determine temp of the engine went to H. He stated there was an air pocket that needed to come out, which meant bleeding the radiator. 

Getting the air out of the cooling system after replacing the radiator or other parts was a pain in the butt. There is a black rubber cap on a metal line at the top center of the firewall. He pulled it off to bleed the coolant system. But found the metal line had rusted down to about 1 1/2 inches from the top. He used a special pointed tool that he gently hammered thought the rust to reopen that line. He then took a pipe cleaner and ran through it a number of times to remove excess particles.

Getting the air out of the coolant system was easy once that passage was open. He simply slowly added water, using a funnel and a water hose, to the radiator opening as excess air and liquid spewed out of that line (like that of a whale or dolphin) that was covered by the black rubber cap near the firewall. He did this for about 10 minutes while the engine was running periodically rearing the engine, which cause it to spew out. When he was satisfied that the air pocket was cleared to replaced the black cap on the metal line. They then ran the engine (raring the engine) until hot air came into the vehicle while the heat was on full blast. 

When everything was running satisfactorily they ensured they carried a jug full of coolant and water mixed together in the original coolant container and drove the vehicle for about 20 minutes. No longer ran hot. This is day 4 without issues.

NOTE: Before removing the rubber cap from the metal line at the top center of the firewall, be careful taking the Jesus clip off so you don't loose it. 

Patricia Ortiz
Realtor in South Carolina


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## texassam (Jun 3, 2015)

Stew said:


> 2001 Pathfinder, 61k miles. Couple of weeks ago, heater stopped working and engine was running a liitle cool. I assumed this was the thermostat gone bad, no other problems at the time. Last weekend, engine overheated, spewed a little cooolant. Took it to the shop, had it pressure tested no leaks, shop replaced thermostat and everything was working well. Then today, same thing happend, heater stopped working and a few minutes later engine ran hot. What could cause the thermostat to go bad again? This sounds like classic bad thermostat to me -- any other thoughts? Also I read on another thread that the 2001 Pathfinder has two thermostats -- one is on the top of the engine where the hose goes from the radiator to the engine block, where is the second and what purpose does it serve?
> 
> Thanks.


I have a 2001 pathfinder. It keeps overheating and there is air in the water lines. I check for water leaks I have not found one yet. But can air get in the water hoses? I have change everything but the water hoses.


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## texassam (Jun 3, 2015)

I have release air from water hoses but it get hot after few miles. I have changed everything but the water pump. What else can I do?


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## Andrew101 (Sep 30, 2015)

Hello,

A week ago I bought 2000 Nissan Pathfinder LE 3.3l V6. Yesterday I was driving to work and after a few blocks engine heated to the max in a few seconds and spewed coolant under the hood and I saw a lot of steam going out, so I quickly turned around and got back home. In the evening, when engine was cold I refilled overflow tank to the max, because it was completely empty and topped up the radiator. In total I filled about 6 liters of coolant. Is that normal? After filling up the radiator I noticed, that coolant is leaking from the top. I took a picture of that, which you can see here: Screenshot by Lightshot I suppose it shouldn't be like that, right? Is it possible to seal the rad by myself somehow or it should be replaced to the new one?
BTW, after refilling I run it on idle for a half hour and the temperature was normal, but hadn't have a chance to test it on the road yet.

Thanks,
Andrew


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## Cusser (Apr 16, 2004)

You have a leak in the rubber gasket between the top and the center; I had similar on my '98 Frontier. There are few radiator shops these days, so installing/crimping in a new gasket is not a realistic option.

Buy a new radiator, that's what I did. Do this immediately before you cause damage to the head gaskets, which may already have occurred. And be sure to bleed out all the air from the cooling system.


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## Andrew101 (Sep 30, 2015)

Cusser, thanks! You were right! Already scheduled an appointment for a repair - they're going to replace a radiator for sure and check thermostat, hoses, etc.


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## orion123 (Oct 4, 2015)

This is in response to all the people with overheating Pathfinders with the 3.5. 


I have an idea on this overheating problem. 

1: Oil circulation problem
2: Water circulation problem

Oil problem? Pull the lower oil pan off (VERY EASY TO DO)

Check the oil pickup screen for clogs. 
Remove the oil pressure sending unit, and start the engine. If lots of oil comes out, you do not have an oil flow problem. 


Assuming its a problem with the water:

Clogged system
Bad thermostat
Water pump is not moving water (air pocket?)

Leaks will NOT cause the vehicle to overheat. The leaks will cause the coolant level to drop, and THAT is what causes the overheat problem. Stop looking for leaks. 

Try installing an aftermarket water pump on the lower radiator hose, and confirm the correct flow direction. This will answer a lot of questions about the cooling system. No flow: Bad thermostat. If the temp drops, its your water pump/ air pocket. If it still overheats, spray the radiator with a garden hose and see if the temp drops quickly. If it does, your radiator is the problem.


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## smills72 (Mar 13, 2016)

munnyn1 said:


> I have intermittent overheating. When going up hills the temp shoots into the red and once on the downhill it comes down to normal.
> 
> I cleaned the radiator system and have 'burped' it several times.


my does the same thing but at times it does it on straight stretch of road


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## Redpathy (Dec 30, 2020)

IanH said:


> did they check to see if you are losing coolant from some where else, like a water pump or hose ? do you check the coolant bottle level regularly ?
> thermostat opening correctly ?
> When your mechanic looks at it ask what checks can be done to determine if any damage has been done by the over heating.
> Check the coolant for acidity ? Compression test ?
> ...


Hear hear me out people has anyone check the oil cooler gaskets or o rings? If your losing oil or coolantits not a secure system the o ring and gaskets go bad , i had my pathy 01 3.5 serviced for over heating but not prolonged overheated, they did test radiators was clogged replaced fan clutch coolant all good, but i did notice and the tec did too that there was a leak in the oil cooler (small leak) i am going to replace that with an oil charge since oil AND colant pass thru there, could be caused of over heating? My pathy overheated again but only 3/4 of temp gauge (wtf) so im suspecting that oil cooler may have a faulty play in the system (losing oil/not circulating coolant), ill try to update on repair if possable since this is my only transpot and im heading from Washington to california and if the repairs works then ill update if not then gods speed.


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## IanH (Feb 11, 2003)

Redpathy said:


> Hear hear me out people has anyone check the oil cooler gaskets or o rings? If your losing oil or coolantits not a secure system the o ring and gaskets go bad , i had my pathy 01 3.5 serviced for over heating but not prolonged overheated, they did test radiators was clogged replaced fan clutch coolant all good, but i did notice and the tec did too that there was a leak in the oil cooler (small leak) i am going to replace that with an oil charge since oil AND colant pass thru there, could be caused of over heating? My pathy overheated again but only 3/4 of temp gauge (wtf) so im suspecting that oil cooler may have a faulty play in the system (losing oil/not circulating coolant), ill try to update on repair if possable since this is my only transpot and im heading from Washington to california and if the repairs works then ill update if not then gods speed.


I replaced the O rings on the cooler bolted to the block. Easy to do. You dont have to disconnect the coolant lines, remove the bolt and pull cooler away from block, insert new O rings and replace. Over the years did my 2003 twice.


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