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?
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.
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.
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?
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?
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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1997 Pathfinder XE
Air Lift Air Bags, Warn Hubs
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.
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.
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..
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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1997 Pathfinder XE
Air Lift Air Bags, Warn Hubs
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
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.
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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