Blown head gasket - symptoms? [Archive] - GrandAmGT.com Forum

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Simpson36
09-06-2006, 02:35 PM
I've read that head gaskets are not a problem on these engines, but I've also read about people replacing them.

How do you know your head gasket is blown?

Getting ready to do LIM on '99 GT 3.4 110k miles and I'm wondering if it's worth while to do head gaskets at the same time.

Typical issue - coolant dissappearing - no apparent leak.

No oil in coolant, no coolant in the oil. Compression check shows lowest 155 highest 175. Did leak down on #6 and it was only 10%. No steam from tailpipe.

Plugs (fairly new) look good except one has white insulator where others are light brown. I'm hoping it is white from a lean condition caused by leaking LIM. Can water leaking into cylinder cause white insulator tip?

Sprucegagt
09-06-2006, 03:03 PM
Leaking coolant will definitely cause a white insulator tip on your plug. The coolant vaporizes in the combustion chamber and basically steam cleans it. Since you have good compression I would not touch the head gaskets. If one was bad a compression check normally will catch it.

Typically a blown head gasket shows up with the cooling system being over pressurized and forcing coolant out of the overflow and low compression in a cylinder.

Slim
09-06-2006, 03:24 PM
I had a blown head gasket on my car. It showed very similar symptoms to the LIM but no oil leaks on the outside of the engine. It was still clean under there but I got the milky oil and disappearing coolant. It never produced steam, but I did have a slight loss of power.

mikep1987
09-06-2006, 10:23 PM
When I had a blown head gasket the oil looked fine, but the coolant looked like a chocolate shake.

Hurricane
09-07-2006, 06:05 AM
I replaced my head gaskets while doing my LIM. they weren't leaking, I just figured since I was in there, I might as well.

In retrospect, I wouldn't do it again. I found the head gaskets to be a bit of a pain. Particularly getting at, removing and replacing the exhaust manifold bolts on the rear cylinder bank.

If it ain't broken, don't fix it. (As opposed to, "If it ain;t broken, it doesn't have enough features!")

Simpson36
09-07-2006, 08:57 AM
I read somewhere that you can pull the heads with the exhaust manifolds attached.