I feel like a complete idiot with this one. I was driving the car home yesterday, and it began steaming out of the right side of the hood. I pulled into a restaraunt parking lot, where I noticed the coolant in the overflow tank had expanded so much it had popped the lid off. The upper radiator hose was heavily pressurized and very, very hot, and there was coolant all over the engine on the passenger side, as well as on the passenger side floorboard inside the car (I'm pretty sure that the leak inside the car came from a bad heater core, but I know it couldn't be responsible for the whole thing). I limped the car home, since the owner of the restaraunt wouldn't let me leave it there even until a tow truck could come (it's a frumpy little five-star place) and my house wasn't too far away, let it sit for about an hour and a half, refilled the coolant, and drove it the all of 25 feet from the road to the driveway. By the time I shut it off, it was steaming violently again.

One friend of mine thinks the heater core was responsible for everything, which I doubt. Another, who knows a bit more about cars, says it's the thermostat. After reading several posts on head gaskets, I'm leaning towards a blown head gasket. My reasoning is as follows:

1. It came up suddenly, after I had been driving the car for two days.
2. Coolant was all over the outside of the block, including around the head.
3. When I pulled the car into the driveway, it wasn't even on for two minutes and had had lots of time to cool down. The only thing I can think of that would have caused the coolant to boil so quickly is superheated exhaust gases.
4. The upper radiator hose was pressurized and extremely hot. A jammed-shut thermostat could cause the hose to be pressurized, but I don't think it would be as hot as it was.

Is there anything else that could cause this problem? If it is the headgasket, is there anything else I should do when I replace them (since so much of the engine is going to be taken apart)? I want to replace pushrods, valve lifters, and every gasket from the head gaskets up, as well as cleaning out cooland and air passages and overhauling the throttle body. I want to get everything done I can in one swoop as long as it doesn't require pulling the engine.

Thank you all once again for helping someone who's gotten himself in over his head.

And I'll post pictures of the car tonight as soon as I get home from work. I promise this time!

- Joe

Start by changing the thermostat. Bypass the heater core if you are not ready to replace it. If you have access to an exhaust gas anaylizer then sniff the radiator (at the cap opening while the engine is idling) for hydrocarbons. Any small detectable amount of HC coming out of the radiator more than what the machine sees from the shop air will indicate a combustion to coolant leakage. Be careful not to suck any coolant into the machine. Auto parts stores also sell a chemical leak checker gizmo if you can't use an exhaust machine. Always use extreme caution around a suspected overheating engine. Something could let go and shower you with boiling coolant.
A blown headgasket is usually a symptom of other problems as well as a major problem itself.

Cool. I'll try to get my hands on one of those sniffers. This is a non-inspection state, but I'm sure one of the local shops would have one. Is there another way to check if this is not an option? The engine began steaming again less than a minute after I restarted it, and I want to be cautious about standing close to it under any circumstances.

How would I go about bypassing the heater core? Is it much more difficult than just replacing it? At ten bucks each, I'd probably just go ahead and replace it if bypassing it isn't super easy.

Thanks for the fast response and good suggestions, Apeman.

- Joe

bypassing the heaTER CORE is super easy. all you have to do is take one of the hoses that come off the heater core off and the other one just take it off the heater core leave it on the engine. then just put the end of the hose that was on the core on the other hose connection on the engine.

Also, see if you can get a pressure tester and use it on a cold engine. If its steaming and coolant was all over like you said, I would suspect a leak somewhere as well. I had a bit of a mess myself with just a 1/2" slice in the heater hose. It pointed straight into the fan and got coolant everywhere, especially the exhaust manifolds. If you check while running, you run the risk of getting hot coolant all over and possibly causing injury if a hose splits.. With the pressure tester, if a hose splits, it just gets very wet.

You can also use it to check the headgasket as well. Pull the plugs and pressurize the system. Then while having someone watch the sparkplug holes, see if any squirt coolant when you turn the motor over. (If you don't like that person very much, make sure they stand in front of the hole when you crank. ;) )

Alright, I'll do all that this weekend.

Do you think it would be safe, if I refilled all the coolant, to try and drive the car the all of two miles to my father's house, where I at least have some sort of cover to work under?

Also, pictures as promised: http://cave-of-shadows.com/81Coupe.htm. Beware, they're not dialup-friendly, and there aren't a lot of them yet.

looking down the spark plug holes is a good idea to check for a blown head gasket but i'd be a little weery about turning the engine over with the starter if there is a leak in one of the cylinders. even though you have the plug out if there is a lot of coolant in the chamber and it is forced out faster than it can go out of the spark plug hole there is a chance of bending a rod. plus you'd have to make sure it doesn't leak into any other cylinders and hydro lock those too.


although i guess if you make sure that not a whole lot of coolant squirts into the chamber you could use the starter to push out the coolant. i'd try getting the cylinder your checking at TDC and suck any coolant out with like an old turkey baster or something.