water control valve ??

[towncarblue]

i have a 2002 nissan pathfinder...im having some overheating issues and im trying to troubleshoot what it could be. ive replaced the waterpump,lower thermostat ,radiator hoses.

to replace the secondary thermostat it looks like a pain in the *ss [gotta remove intake manifold] does the water control valve directly deal with the cooling of the vehicle or is it just for the cabin heating system ?how can i tell if it is in need of replacement?would a damaged water control valve cause the engine to overheat? at dealing with pathfinder engines

[Pwnin O'Brien]

Well, it's kinda complicated. The factory service manual does not state that the water control valve can cause engine overheating. However, if you look at the cooling system diagram below, you can see that if the water control valve is stuck in the closed position, the water in the engine block has nowhere to go. This blockage caused by the closed water control valve would then prevent the block from cooling. Do I think this would cause the vehicle to overheat? Probably, but not severely, the cooling system can operate normally with the water control valve closed. The main purpose of the water control valve is to allow the engine to warm up faster from a cold start. The only way to check if the water control valve is working is to remove it from the vehicle and do a boiling water test.

I would probably start by checking for air in your cooling system. Did you flush the cooling system yourself when you installed the new water pump, hoses and thermostat? If there is any residual air in the system, that can definitely cause your vehicle to overheat. Did you thoroughly flush the radiator? You should have removed the radiator from the vehicle and flushed it thoroughly using a garden hose (although you could do it on the vehicle if necessary). Have you checked for proper operation of your fan clutch? The best way to test it is to spin the fan with your hand (with the engine off) and see if it spins freely. There will be some resistance and it wont spin for very long.

I would check those things before checking out the water control valve.


Modified by Pwnin O'Brien at 11:18 PM 11/2/2009

[towncarblue]

i have already replaced the fan clutch.forgot to mention that ive never flushed the radiator... i will try it tomorrow and refill the coolant to see what happens.

[towncarblue]

i got the upper thermostat replaced today.i noticed something curious ........ while refilling the coolant

the plug located on the firewall that is supposed to let the air out of the cooling system was clogged with a black substance, it felt like a grainy paste.i dont know if i should use a wire hanger to break it up or just leave it alone.what should i do?
Modified by towncarblue at 7:21 PM 11/4/2009

[Pwnin O'Brien]

i got the upper thermostat replaced today.i noticed something curious ........ while refilling the coolant

the plug located on the firewall that is supposed to let the air out of the cooling system was clogged with a black substance, it felt like a grainy paste.i dont know if i should use a wire hanger to break it up or just leave it alone.what should i do?

Well, that wouldn't really cause your overheating, unless when the coolant was changed last the person couldn't get all of the air out of the system due to the blockage at the air relief plug.

When you refill the cooling system, you're supposed to pull the air relief plug off when filling and then replace that plug when coolant starts coming out of it (to purge all air from the system). When you filled the cooling system and tried purging the air through the air relief plug, did coolant start flowing from it?

[towncarblue]

no. the plug is completely clogged. i dont think any air or coolant could escape from there.

[Pwnin O'Brien]

no. the plug is completely clogged. i dont think any air or coolant could escape from there.

Then you definitely want to unclog it. You need that clear so you can purge all of the air out of the system (since it's the highest point of the cooling system). I would recommend trying to slide a slightly larger hose over the air relief hose and making a vacuum to pull out whatever is clogging the hose. You can also try using a wire hanger to clear the blockage, but be sure to thoroughly flush the cooling system afterward to clean any of the black stuff out that you may have pushed in.

[hussain00]

i am having similar issues on my 2002 Infiniti QX4. just kinda curious if unclogging the plug fix your overheating issue?

Thanks

[Pathy415]

I know a damaged/blown head gasket also cause the overheating and may also cause contaminated build-up in the cooling system. Are you loosing any coolant? What color is the engine oil?

I don't mean to get you alarmed but I've seen cases similar to what you described and usually it's a head gasket issue.

[attofarad]

i got the upper thermostat replaced today.i noticed something curious ........ while refilling the coolant

How long did it take you to replace the upper thermostat (water control valve), if
you did it yourself, or how much did it cost if you had a mechanic to it?

My wife's is leaking, either there or at one of the crossover pipe gaskets. Can't
really see without a snake/inspection camera.

Gary

[Weekendworrior]

I had an overheat a week and a half ago. New my radiator had a small crack. Tried to patch it, no luck. I knew it was a 16yr old radiator, fix one crack another will appear.

Replaced it filled it up. Car would stay at operating temp if I just start it cold and not drive it. As soon as I go 1/2 mile down the road it overheated and I had to shut her down. Then I think thermostat.

Open my book and learn there's a control valve and a main one. I did not want to deal with the control valve so the replaced the thermostat. Fill everything back up.... overheated.

Thinking the valve or the pump....(also tested the thermostat... it opened fine) I didn't see a lot of flow coming through the radiator with a warm engine so I'm thinking pump. Replaced the pump (if you do this unbolt the chain tensioner b4 rolling the crankshaft back to give yourself more wiggle room to remove the pump). The pump was fine.... replaced it since I was holding a new one in the other hand.

Today I read about the vent against the fire wall and start thinking... Mine was clogged too. Used a wire to clear it. Then a hand pump to vacuum out the debris. Kept going till fluit was coming out. Topping the radiator off. The overheating was better, not perfect. Started pumping fluild through the hole on the top till the radiator was overflowing.

My Pathfinder is now fixed!!! I'm so glade I found myself here. Otherwise I would of replaced a good control valve....and cried