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1999 Chevrolet Malibu Overflowing Coolant Tank

I have a friend with a 1999 Chevrolet Malibu, V6 who had a head gasket leak. Several cans of Barr’s stop-leak later, the car seemed well. Then, it began overheating the coolant and sent it boiling out of the coolant tank until the tank’s empty. Several professional mechanics I’ve questioned cannot explain why. And my friend is in desperate financial condition and cannot afford to have the engine torn down. Any ideas?

It is very rare that Barr’s Stop Leak will fix a failing head gasket because the temperature and pressure are too great. What you describe is a classic sign of combustion gases getting into the cooling system. If you want a quick confirmation of the leaking gases, have a mechanic sniff the air over the open radiator neck and see if combustion gases are detected. I think there is a test strip kit that can also test for combustion gases that you can get at the auto parts store.

If your friend is unemployed at this time, he/she might attempt replacing the head gasket. Get the Haynes or Chilton manual for the car and have at it. The car will be laid up for a while but it will be a lot less costly.

Good luck on this.

What I’ve used to stop head gasket leaks is sodium silicate. This can be ordered through a local pharmacy for about $20.00 for a 12 oz bottle.

Pour the liquid glass into the cooling system, fill the cooling system, and start the engine and let it go to work. This repair may last two hours, or two years.


If the directions on the package are followed to the letter there is a somewhat better than 50-50 chance that the stop leak will work. If the directions are not followed exactly it’s a waste to even try the junk. Pulling the heads and properly repairing the engine is the only certain way to reliably repair it but that is a heck of a job for an amateur.

I said Barr’s but I’m not sure exactly sure what product was used. I remember that it was specific for head gasket leakage. The exhaust gas leak seems logical and I appreciate the response. Now he knows what he’s dealing with.

Thanks for the suggestion.

I agree and the disassembly of the the engine topside is a nightmare with all of the plumbling. Especially when you don’t have the necessary tools.