PLEASE HELP ME DIAGNOSE THIS PROBLEM. I have been looking and can't seem to find anyone with this same problem. First of all I have a 03 WRX with 60,000mi. only mild mods like prodrive axle back, grounding, etc.

My car runs great and has no other symptoms but this. If I am driving, no matter how hard, she runs cool as the day I bought her. If I have been driving and then stop and idle for a min or so the temp gauge will shoot up to H in like 10sec. If I rev the engine once or twice the temp will fall back to normal within another 10-15 seconds. It may do this cycle once ot twice but then it will stay cool. It doesn't do it all the time but I have noticed it about 5 times in the past 3 days.

I have checked the fluid and it looks good and is at the right level. The belt on the waterpump looks ok and is tight to spec. The fans work and run as they are suspossed to. The radiator hoses both look great. And like I said I can run 130 in the CA heat and she runs cool but when I stop the temp flys up.

My first thought is that its the thermostat getting stuck but I just don't get it. Please help me figure this out. :confused:

Ryan....

You probably have a big air bubble in the system. Did you recently change the coolant?

The system is self bleeding, though you can help it along. Do a search, I'm sure this has been covered before.

could be thermostat of like wallace said, air bubbles. drain coolant, add coolant while burping the system.. also do a search

I would try the simple stuff like air bubble or thermostat first. However this is deja veu on our old Honda. A weak water pump was the culprit in our case.

Also since you have 60,000 miles you possibly in warranty with this? Remember it starts with delivered miles.

The air bubble would cause the temp to go up not just at idle. Without a real temp meter you would not know. If its not a bubble, then the the thermostat or water pump is more than likely the culprit.

Maybe a screwed gauge/wireing. Its shouldnt move back and forth that quickly.

Thank you guys for the quick replys. It looks like I'm going to replace the fluid and thermostat first. I hope that fixes the problem.

Is there any way to check if the water pump is functioning properly? I would just replace it but I'm in the middle of opening a new business right now and I have no extra $$. I was hoping to make it to 80K or so and replace it along with the timing belt and tensioner. I have already replaced the 2 accessory belts.

Something simple like a plastic bag covering part of the radiator?

Unfortunately it's not something blocking the radiator. That would have been a great cash friendly fix. ;) I'm going to order some parts today to try and fix this as soon as I can. I'll probably look to see how much a water pump is and maby do it at the same time. It just kills me to have to spend $$ on parts that don't make the car faster. :devil: But, I have to drive way too much to be without my car. I'm thinking of getting the crucial racing summer kit with the samco hoses, water wetter, cap and thermostat. At least I'll get some pretty engine parts so I can feel like I'm fixing her up instead of just fixing her.

A bad rad. may not be allowing the air (if any) from purging from the system.

A lazy t-stat can certainly cause this.

But it sounds like it's the water pump because you said that when it's warm and you rev it that the temp drops quickly. If the coolant in the radiator is not circulating it gets pretty cool. YOu rev the motor to get the water pump going and woosh, the hot fluid is replaced by the cool stuff in the rad. and the tempo drops.

That's my theory anyway. I also would'nt doubt that you have an oily t-belt and need a new front main seal.

Good luck.

I'm thinking of getting the crucial racing summer kit with the samco hoses, water wetter, cap and thermostat. At least I'll get some pretty engine parts so I can feel like I'm fixing her up instead of just fixing her.

Those are the first things you should replace instead of the water pump

Thank you guys for the quick replys. It looks like I'm going to replace the fluid and thermostat first. I hope that fixes the problem.

Is there any way to check if the water pump is functioning properly? I would just replace it but I'm in the middle of opening a new business right now and I have no extra $$. I was hoping to make it to 80K or so and replace it along with the timing belt and tensioner. I have already replaced the 2 accessory belts.


Check and see if it is the water pump. If it is, and you are under 60,000 miles, it is covered under the powertrain warranty. It is probably something else, but it won't hurt to check it.

Time timing belt on your car is also not due until 105,000 miles, but if they have to replace the water pump, pay for the belt and have it done at the same time,.

Forget the WW and just use Subaru oem or GO5 (PepBoys) coolant and mix 50/50.

:confused: Well I'm thinking I may have a bad radiator. I looked at the resevoir again a few days ago and it seemed a little low so I added a little H2O and since then I have not had the temp go up at all. I've probably put on another 500mi or so. My baby is actually running freaking great. But I did check the coolant level in the overflow again yesterday and it was almost dry again. I took the car to talk with a few techs, worried about it being a head gasket, and since the fluid looks good and I'm not blowing any smoke they think I must have a small leak somewhere that had caused an air bubble in the system that gave me the overheating symptoms I was having. So, I have been looking for a leak and cannot find one. I have a small one car garage and sometimes when I pull in hot, normal temp, I can smell the faint smell of radiator fluid in the garage and if I do a sniff test the only place I can smell radiator fluid smell comming from is around the radiator. I just do not see any obvoius signs of leakage. I'm at 63000mi so no warranty, so is there an easy way to detect a small leak in the radiator????

I forgot one thing too, when I put water into the overflow tank yesterday I then had air bubbles comming out of the black rubber hose hanging in the overflow tank for a few minutes. I had never seen this before and wasn't sure if it was something normal or not....