Hello all, i just replaced both the thermostat and WCV on my 2000 nissan maxima. After replacment i am still having overheating problems.

Heres where im at so far: the heat rises slowly and settles about halfway up the gauge (as it usually would have). Both fans work, coolant seems to be circulating becuase both the top and bottom radiator hoses are hot.BUT the radiator is still cool if not cold to the touch. Even the top of the radiator is cold which is strange to me if both hoses are hot because it would seem its flowing through the radiator.

The strange thing is somtimes it seems to circulate and the pin on the dash will drop but if you take it for a short drive it will over heat. If you leave the engine run after stopping during an overheating scenerio the engine will slowly cool and return to normal opperating temp.

SOLUTIONS: - Maybe the radiator is clogged up?
- Air in the system?
-Water pump is operating SOME of the time?


Any and all help is truly appreciated, thanks all.

 

When you drained the antifreeze to replace the thermostat, what did it look like? Was it a nice, crystal clear green (or whatever) color?

A possibility, especially if the antifreeze was worn out, You can take the radiator out and try reverse flushing it with a garden hose.

A possibility. Raise the front of the car a good foot or so. Starting with a cold engine, remove the radiator cap. The top tank of the radiator should be completely full, no air space. Drain some of the coolant out so that the radiator top tank is about half full. Start the engine and wait for the coolant to warm up so the thermostat opens. If you have air pockets, you may hear gurgling sounds, or not, but the coolant level in the radiator will go down. fill the radiator if needed, all the way to the top and replace the radiator cap.

The water pump cannot operate just some of the time. It is driven by the timing chain. What is possible is that the impeller blades could have corroded away to nothing, especially if the antifreeze was worn out.

see the photo in post # 31 in this link:
http://forums.maxima.org/5th-generat...-speeding.html

 

the coolant was a bit murky (Greenish orangish) and one thing i failed to mention, which was curious, was that when i took the thermostat out there was no coolant in that hose, i mean bone dry. So naturally the thought of water pump came to mind. If its not circulating coolant then either the new thermo will solve this (possibly stuck closed) or the hose will get hot upon starting the car with the new thermo meaning the water pump is operational.

im going to pull the radiator and flush it tomorow. i figured that would be a solid first step.

 

You never told us the mileage. Unless the cooling system was severely neglected , the water pumps in these cars should last a very long time.

 

mileage is 168k

 

It won't circulate if there's tons of air in the system.

 

Get the car up in the front, that usually helps with the burping....use A darn street curb if you ain't got ramps or jack stands. After lifting car up, start with A cold engine, remove cap to radiator and fill it to top, start car and put heat on and all the way up. Leave cap off whole time and wait for couple cycles to pass (15min), shut off car, restart and keep an eye on radiator where fluid goes, if it goes down add more, you should hear bubbling sounds of air coming up.....keep doing this for anoth ten min.....put cap on take A drive and see. Fill reservoir.