My beloved Evo 9 GSR has developed a strange problem today...
I was cruising on the motorway normally with the air-con on, suddenly I noticed the water temperature was rising almost to the top and oil temp was 114c. I immediately pulled over to check the car, fan was on full blast everything seemed normal but the temperature kept rising.
I decided to drive home immediately and turned off the air-con, it did help and on the motorway the temperature remained at normal.

But once I got to stop-start traffic the gauge goes up and down really quickly..
Now I got home...checked again, fan is on full-blast again...strange strange
Later I'll check the coolant level just to make sure.

ON a note I'v been hearing a belt squeaking noise for 1-2 sec every morning when I start the car cold, could it be related?

 

So, you've already checked coolant levels and oil levels? If its not those, I would suspect a bad water pump.

 

Will check those 2 later, give it another hour to cool down.
A bad water pump...em...is it going to be a big job to replace?

 

may want to start with the more likely culprit first--like a thermostat

 

Well, the bearing in the water pump can fail and take the seal. What you have then is disappearing coolant and a big leak. Other than that, what is a bad water pump?

 

thermostat-- pull the thermostat out and see if it still the same

 

How many miles on the car?

 

Went through a similar experience. For me it was just the sensor for the gauge in the cluster. It would go high and low constantly. Never was really overheating

 

Milage is around 40k miles, 2005 car.
I've checked the coolant, it only reached the "min" mark instead of "max" mark yesterday, no water leak as far as I can see.

to 05VIII: Was your experience similar to mine, say the temp gauge went up when stopped and went down when moving? If so then I'll look into that as well.

 

Check the temp sensor on the bottom side of the water neck. If coolant has been leaking on it, it can show variable readings. It is not an expensive sensor so replace it and make sure to take care of the leaks.

 

The first and cheapest part to replace is the radiator cap. I would replace that first and go from there. When it's cool pull the cap and see if the coolant is at the top.

N

 

same thing is happening to me as we speak, no visible leaks, not that the car is actually heating up but the temp gauge goes up in higher speeds. im hoping its just a sensor or thermostat everyone else thinks my headgasket is going i definetly hope not

 

My opinion most likely a thermostat i had a similar issue were the car would over heat some days and others it would be fine so your thermostat could be going i changed my thermostat and the issue went away, like people had said previously check coolant levels frequently as well

 

Check for a stuck thermostat.

 

Chances for a thermostat failure are low.

I'm pretty sure it's just the gauge temp sensor. Like mentioned before, order a new sensor since it's cheap and easy to install. Make sure you order the rite sensor. There are two on the thermostat housing. One in the rear is coolant temp sensor, one in front is the gauge sensor. The front one is the one you should check. For me, coolant leaked onto the sensor and caused it to go up and down.

Try this. Drive the car around for a while, park it for 30 min or so, then hop in and turn the key to ignition without starting it. If the gauge shoots up then it's prolly that sensor. If it's cooled down(1/4 way up) then probably something else