# 2000 Nissan Pathfinder Overheating



## NY98M# (Jun 23, 2004)

Truck has 155K miles on it and it started overheating.

A few months back I replaced the water pump and thermostat while I was changing out the timing belt. Everything worked great for about 15K miles until 2 weeks ago when it overheated. I figured it was the head gasket because there was a yellow milky substance under the oil cap.

So I tore it down and replaced both the head gasket. After 3 days of working on the head gaskets, I started the truck and it over heated again.

So as a last report, I used Bar's Leaks Head Gasket Sealer in the cooling system. That didnt work either. 

I can drive the truck locally for about 20 minutes before I see temps rising higher then normal into the hot zone. 

What can this be? Its driving me nuts because my wife and I just had our first child and dont need this right now. 

What else could it be?


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## NY98M# (Jun 23, 2004)

Any help would be appricated! 

Also, just checked the thermostat and its working fine. 

Yesterday I let the truck idle for an hour with no overheating problems. As soon as I drive it, the temps went up.


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## Pwnin O'brien (Jan 8, 2009)

I'm not too familiar with 2000 Pathfinders, but when you replaced the head gaskets were you able to test or replace the second thermostat on the rear of the engine? That could also be malfunctioning, although I doubt it would allow the engine to overheat.

To be safe, I would probably get a cooling system compression checker as well as a cylinder compression checker. Those two tools will ensure that your issue is not a crack in the heads or engine block. A crack in either is not visible by the eye. When you drive, does any smoke come from the tailpipe? Rev the engine a couple of times and check for smoke, also smell the smoke and describe its smell. After about a week, do you notice your coolant level getting lower?

I highly doubt this is you problem, but you may want to have your radiator thoroughly flushed as corrosion could clog the radiator and cause the vehicle to overheat. One way to check yourself without having it flushed is to run the vehicle until it is at normal operating temperature and then turn the car off and then physically feel around the radiator (the side facing the fan) for any colder spots. This is extremely difficult to detect but worth a try.

Let me know if this was any help.

(P.S. Bars stop leak will actually gum up in your radiator when the vehicle is turned off and can cause the vehicle to overheat worse. I have had a long history with Bars stop leak products and sometimes they can work, but they never work for long, and you will find yourself using it once a week, this will then lead to cooling system failure.)


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## NY98M# (Jun 23, 2004)

The coolant was getting lower even after I did the head gasket which is leading me to beleive its a cracked head or block. Thats why I used the leak stop. 

I felt the radiator, the tops are hot and the middle is COLD. I dont think the fluid is getting from top to bottom. I actually used a temp gun wit temps on the top of 195 and the middle being 70.

I just want to fix the truck to sell it.


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## Pwnin O'brien (Jan 8, 2009)

Here is what I would recommend (ONLY if you are selling it to a dealership, not an individual), you can flush the entire cooling system at home using some cooling system cleaner and a strong stream of water. This can be done quite easily and cheaply at home. As for the cracked head/block, I would recommend attaining a cylinder compression checker to see what cylinder(s) has the crack(s). You can then purchase a liquid which you can actually pour into the cylinder which will fill the crack indefinitely. I have never used this type of product before, but I'm sure when you go into your local parts store they can tell you what you need. 

This will make the car run like normal so that you can sell it. When you take it to a dealer, they will probably do a fluids check and if they find Bars Stop Leak in the coolant, they will likely refuse to purchase the car or offer you a MUCH lower price for the vehicle.

There is a slight chance, however, if the Bars stop leak is currently working, you may just be able to flush the system without disturbing the sealed crack and then you can just quickly sell it.

I have a looooong history with cracked engine blocks and I have successfully sold a vehicle to a dealership with a severely cracked block and they had absolutely no clue.


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