1985 Toyota Pickup overheating mystery



My '85 pickup was running OK last year when I bought a new Corolla and stopped driving it. It was using a little oil and a little coolant but not an excessive amount.

One year later I started it up and now there is water in the oil and it is overheating. The mechanic said it was a blown head gasket and he put in some block sealant yesterday.

How long will it take before we know if the sealant is working? It was still overheating today.

Also I read something that said you have to add the sealant to water, that it will not work with antifreeze. Is that true?

He didn’t change the thermostat. Would changing it help?

I had a new radiator and water pump put in about 30.000 miles ago. the truck has about 204,000 miles on it and the head gasket was replaced once before. It was a long time ago.



I wouldn’t count on the sealant, not for a head gasket leak. It’s not just a matter of plugging a simple coolant leak. There will be hot, pressurized exhaust gas going the other way too.

The only real fix for this will be a new head gasket.

Forget trying to seal it.  The head gasket must be replaced.


The fun thing about cooling system sealing products, like Bar’s Leak and things of that ilk, is that they actually do a pretty good job of sealing! Unfortunately, while they often will seal little pin-holes in say, a heater core, or a thermostat housing, they usually won’t fix a leak in to the combustion chamber. Also, your radiator is nothing but a bunch of really small passages all linked together, and if you get some sealant globbed together in sufficient quantity, you can “seal” that puppy up tight.

General rule of thumb: unless you need it to cross the Mojave or something, don’t use sealing additives in your cooling system.