Overheating Continues

shotgunslade · #1 08-21-2006, 06:02 AM

After my Friday track day, I though I had my overheating problems fixed, but a new gremlin has arisen to give me grief. I noticed it first on Sunday. Went to the car wash, and the temperature, right after starting, with only in town driving, rose right up to the red bar. After a little bit, it dropped down to mid level, stayed there, and then a little while later rose up to the red line. Putting the AC on and off seemed to have some effect, but its not consistent. Sometimes, turning the AC off or on would initiate a change, other times not. All of this is occuring at very low rev's, in-town, modest acceleration. The fans are running.

I read all of the threads about head gasket blow-by, boiling the coolant. Thought that might apply because of my experience at the track. But, this isn't consistent with that. It is too off and on. Normal, then hot, then back to normal again. No in-between and not linked to accelerator use. I'm betting on a balky thermostat. Have ordered one, will change it, but will get the HC coolant test at the same time.

Any thoughts?

Manarius · #2 08-21-2006, 07:35 AM

I think that you might have a semi-block in one of the coolant lines. That would account for the pegging of the redline, only to come back to the middle again.

immortal_suby · #3 08-22-2006, 07:19 PM

mine was pretty inconsistent with a bad head gasket. some days I had no problem. some I overheated quickly. the only thing that was consistent is that it got worse over time.

dwd1985 · #4 08-22-2006, 07:23 PM

I would agree that it sounds like a sticky thermostat. Mine did that when my thermostat was heading out. Replacing it fixed the problem right away.

msvx95 · #5 08-23-2006, 04:49 AM

Bad thermostat would cause the up and down fluctuation....Head gasket would peg the needle and stay there after car is warmed up.

SilverSpear · #6 08-23-2006, 04:58 AM

Change the termostat first... but he also could be facing a water pump failure or a bad Rad.

shotgunslade · #7 08-23-2006, 03:46 PM

Thanks all. Radiator is only 6 months old. Needle definitely doesn't stay pegged after warm-up. The other day, it was heading up toward the red-line, and I turned on the Climate control and set the t'stat at 80. (to make it go in heating mode as it was about 75 out). Needle immediately dropped down to less than halfway. Often see quick drops down to normal after needle slowly rises us to redline. Still betting on t'stat. New one to be delivered tomorrow.

Hocrest · #8 08-23-2006, 03:51 PM

Mine is doing the same thing, let us know what happens...

immortal_suby · #9 08-23-2006, 06:43 PM

Quote:

Originally Posted by msvx95

Bad thermostat would cause the up and down fluctuation....Head gasket would peg the needle and stay there after car is warmed up.

It might depend on where the head gasket fails.
Mine had no oil/coolant mixing or loss. I was just overheating the coolant from blow by and that was causing boil over into the expansion tank.

But - if I drove it easy it could heat up and cool down. Running the heat on high would usually keep it cool. It wouldn't stay overheated unless I beat on it or the coolant got low. Alot of times I could take long highway trips with no problem and then when I stopped or slowed down for traffic the overheating started.

msvx95 · #10 08-24-2006, 04:40 AM

My legacy had oil/coolant mixing and overheated right after warmup from the bad head gasket...but I see what you are saying....depends where or how the gasket fails.

It's Just Eric · #11 08-24-2006, 10:08 PM

Just a bit of curious input here...would using a thermostat the opened at a slightly cooler temperature possibly prevent some of the problems associated with track driving? I would imagine having it open earlier may help prevent some heat build up

But then again, Im probly wrong. fluid dynamics and engineering seem more your forté than mine

SSSVX · #12 08-24-2006, 10:23 PM

Quote:

Originally Posted by immortal_suby

It might depend on where the head gasket fails.
Mine had no oil/coolant mixing or loss. I was just overheating the coolant from blow by and that was causing boil over into the expansion tank.

But - if I drove it easy it could heat up and cool down. Running the heat on high would usually keep it cool. It wouldn't stay overheated unless I beat on it or the coolant got low. Alot of times I could take long highway trips with no problem and then when I stopped or slowed down for traffic the overheating started.

Did you change your thermostat and see if it made any difference? How did you end up knowing it was your headgasket? When you had that problem, is your temp going up on driving up hills and coming down when driving down hills??

SSSVX · #13 08-24-2006, 10:28 PM

Quote:

Originally Posted by shotgunslade

Still betting on t'stat. New one to be delivered tomorrow.

Got the T'stat? How was the HC test?

shotgunslade · #14 08-25-2006, 02:31 AM

Been out of the country. Thermostat goes in this weekend. Will get HC test at the same ime. Will keep all posted. Thanks for your help.

The speed at which the temperature drops when it decides to drop ( like seeing visible movement of the needle as it drops rom the red line to just below horizontal, cooling down to normal temperature takes less than a minute) tells me that there is some kind of on-off thing going on. The on-off behaviour doesnt seem to be relating to motor strain, power-on, accelerator, etc. It heats up even when driving slowly with very slow acceleration, then will sudenly cool off.

Earthworm · #15 08-25-2006, 10:23 AM

I hope you fix the problem soon...all the hot-cold-hot-cold is bound to warp something!