Blown Headgasket 1999 Deville

[tazzyme]

I have a 1999 Deville with the northstar engine,I've replaced the radiator and water pump,but am still losing coolant,does anyone know of,or if any of these head gasket sealants in a bottle,do they really work? If so what is a good one for the northstar engine?

[KHE]

Is it just loosing coolant or is it overheating also? Test the coolant for combustion gasses using a tester from Napa, Autozone, etc. Do not add coolant prior to testing the system or you'll get a false negative result.

If you have a badhead gasket, no sealer in a can will repair it - the head bolt holes in the block must be repaired with inserts.

[Aeon Long]

Also keep in mind if the fluid turns a greenish blue, you are in the beginning stages of failure, mine wouldn't turn full yellow with the block tester fluid, but kind of green.

Another tell tale is if you get it good and hot and you get the gurgles in the overflow tank where the hot exhaust gases push the coolant out and you have to wait 15 minutes for it to finish howling before you can add water again.

I can smell coolant especially on a hot engine, you will smell it leaking if indeed you have a leak.

Also if you let sit overnight and you get a stumble in the morning on a cold engine, you most likely have coolant in a cylinder.

[Cadillac Jim]

Another tell-tale sign of early head gasket leakage is a smell of coolant in the tailpipes. The easiest time to find that is in the morning. Start it first thing, and as soon as it settles down walk to the rear of the car and see if you smell coolant.

Another tell-tale once the problem is a bit worse is a smell of exhaust in the coolant tank.

[KHE]

I have a 1999 Deville with the northstar engine,I've replaced the radiator and water pump,but am still losing coolant,does anyone know of,or if any of these head gasket sealants in a bottle,do they really work? If so what is a good one for the northstar engine?

Have you verified the purge line is clear/flowing properly?

Have you looked for external leaks?

[Cadillac Jim]

KHE has an excellent point. Most overheating problems are with the cooling system, not the dreaded head gasket failure. One of the most common problem is a clogged bypass or purge line, which will mimic the symptoms of a head gasket problem but is easily and inexpensively fixed.