Overheating

[asshanson]

First off, completely stock 7 bolt motor on my 96 talon. No ARP headstuds or anything, the engine head probably hasn't been off the car even. I recently put on a 20g turbo, but everything has been going pretty well since then, no huge problems. At the dyno day it was blowing smoke after each run, not sure if it was gray or white smoke, but I figured it was because it was running super rich, way less than 10/1.

My car was running fine until yesterday, when out of nowhere it's running way too hot. Since I put on the new turbo I've only floored it in 1st gear a few times, but several 2nd and 3rd gear pulls. Yesterday after work I decided to have fun at WOT for 1st through 3rd gears. 5 minutes later the temp guage was pegged at hot and all the coolant is bubbling and overflowing. I had a gallon of water in the trunk and waited for it to cool off, refilled it, and started driving again. The temps just kept rising, and it would cool off a little when idling. Even going 40mph in 5th gear it overheats, but not at idle, just any little amount of load.

So I thought I blew a headgasket and starting checking things today. There are no obvious coolant leaks, at least nothing is dripping out coolant all over the ground, nothing that would make it overheat in 5 miles of driving. I did a compression test, results are something like 170, 175, 190, 190, and the tops of the pistons looked dry. It's about a quart low on oil, I was just going to change it this weekend. It's also been using a little coolant since I got the car, but nothing really unusual, I just have to put more in the resovoir every 6 months.

I also checked the pully for the water pump, it's not loose or anything, and all the belts seem to be in place with good tension, nothing is slipping. I haven't checked if anything is wrong with the heater core yet.

Any suggestions on other things to check tomorrow? I'm out of ideas, and I dont know how to do a leak down test. I'm stuck in Des Moines, so I can't take it to any of the shops up there. I have almost all my tools here though so I can do quite a bit, but a headgasket may be tricky here since I've never done one.

[FattyBoomBatty]

Well, the weird compression numbers could be an indicator, but you could also have a faulty thermostat. Pop that guy off and put it in a pan of water on the stove, heat it up, check the temp of the water when it opens. Or, if could be completely broken, I had that happen once, but it would never heat up. so, I dunno. Running super rich could also have something to do with that, though I think if timing was way off that would cause more of a problme, and i bet that has nothing to do with it.

good luck.

[JET]

My first guess would be a blown HG. It sounds a lot like it. Bad radiator cap would also cause it, as would a bad water pump. I had a car with a bad head gasket give similar readings to yours, it was a bit low in #2, but not much. When I pulled it off it was obvious though. Take the car for a short drive and be really nice to it, bring it back and see if the coolant is bubbling out.

You can also check the water pump by pulling out the T-stat and leaving the coolant a little low. Start the car from cold and see if the coolant is moving by. The water pumps in our cars are usually really good and start leaking if they have a problem.

[blageo23]

My car was bubbling out once and everyone said it was the HG. I changed the rad cap and it was perfect. Another thing to check if its the HG is start the car and feel the upper rad hose. If it get really stiff after only a min or so then its most likely that the cylinder is shoving some of the compressed air into the system. If you have a cylinder leak tester that is the best way to check the HG.

[dragonforce]

Sounds like you have a combustion leak.

[turbotalon1g]

test teh cap, sounds like you could of lifted the head.
Also filling a DSM with coolant when its already at running temp is a good way to kill it, i hope u put it in the overflow.

[blageo23]

he said he waited for it to cool down.

[turbotalon1g]

^so a couple of hours then?
Cause dsms get cold within about an hour right.

[blageo23]

Mine gets ice cold in like 10 min. Doent yours? If not I think you have a problem. I mean cast iron disapates heat really well and all. :)

But I guess cooled down to me is different then cooled down to others.

[asshanson]

I didn't want to take off the radiator cap when it was hot, I filled the overflow bottle after 20 minutes or so. Never tried to take the cap off since I was afraid it would explode off. By the way, why would this kill the car?

Anyway, took off the upper radiator hose and couldn't find the thermostat, maybe the previous owner took it off? Where is it at on a 2g? Here are some pics, looks like there is a decent amount of gray RTV on both surfaces. So should I put it back together with a gasket and make sure the water is flowing? I'm really a noob to all of this, any help is greatly appreciated.

Oh, I just did another compression test, this time with the motor completely cold, and it was 160, 180, 180, 190.