I have a question about overheating. Earlier today while running an errand, I left my car idling in the driveway of a friend while I was inside for about 15 minutes. When I came back out, the temperature gauge was all the way at hot (right at the top line, but not over).

It turns out that the fans are not kicking on. My question though is, how much damage could have been done in that amount of time? Also, when these cars overheat, does the needle just go the the top line and stop, or will they keep going over the "H" when really hot?

If damage did occur, what would be most likely? Head gasket or warped head?

The car is an '04 WRX. Thanks.

 

no they go alot further than the top line, i had one pegged way above,... way above. as far as the damage yea it could blow a head gasket, or warp the heads, but if u dont have a check engine light, chances are that didnt happen.

 

What do you think the chances are that the head would warp in 10 minutes of just idling? Considering the needle didn't peg way over the "H"? (It just barely got to the "H")

 

if you arent buring/leaking oil excessivly, then you probably dont have warped heads. youll also notice a big decrease in power. also, the car was idling. if you were driving and it hit the H, then you may have a problem.

 

What would be the best way to check for any possible damage (other than coolant in the oil)? Would a compression test do it? Or should I try something else?

 

dont be so paranoid, u have no check engine light and no water in oil, dont sweat it.

 

just check around, look for anything unusual like oil or coolant coming out, weird response from engine. if nothing is screwing up then you should be fine.

 

Actually a check engine light came on the next day. But I haven't had a chance to get the code read yet because I had to go out of town. So we'll see what it's for on Monday. But the car seemed to drive fine (drove it about 60 miles after the overheat).

 

overheating can cause critical damageto your motor. subaru pistons and rings are a pretty close fit, and overheating will cause them to swell, scuffing the crap out of the cylinder walls. yes, you may well blow out a head gasket (ususally the driver-side, but not always), and start leaking coolant and/or oil fromt the rear of thehead-block mating area. if that happens, you'll have to pull the head to replace the gasket, and you can inspect the cylinder walls for scratch marks that go the same direction as the piston travel. if there are scratches there deep enough to feel with your fingernail, you're probably looking at a new block...basically a new whole short-block assembly, since that's about the same price, bottom line (cost+labor).
~Erik~
Subaru dealer tech

BTW, where in UT are you?

 

Salt Lake City. You? Now although it is always possible, isn't it more unlikely that that gasket would have blown in the amount of time that mine was idling hot?

 

unlikely, yes, but certainly worth at least a ittle check. if you can get under the car, in the following days or weeks check where the head meets the block. oil and/or coolant starting there is (most likely) a blown head gasket. if not, then you're good to go (but check back periodically).
~Erik~

(Utah Valley... )

 

Cool, I'll get under it later this week. And it looks like the check engine code was for the unplugged fans. Thanks a lot.

BTW, you work down there? Going to school or anything?