Blown head gasket - symptoms?

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.

09-06-2006, 02:35 PM	#1
Simpson36 GAGT - Newbie Join Date: Oct 2005 Location: Phoenix, AZ Posts: 13 Vehicle: 1999 Grand Am GT	Blown head gasket - symptoms? 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?

09-06-2006, 03:03 PM	#2
Sprucegagt Schwartz Power! AKA: Andy Join Date: Aug 2002 Location: Ranson, WV Age: 38 Posts: 2,027 Vehicle: 2000 Grand Am GT	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. __________________ 2000 Grand Am GT (some day it will be SC/T) Mods: alot

09-06-2006, 03:24 PM	#3
Slim Captain Canuck AKA: Matt Join Date: Mar 1977 Location: Burlington, Ontario Age: 36 Posts: 3,593 Vehicle: 08 Acadia, 05 Mazda 3	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. __________________ Canadian to the core!

09-07-2006, 06:05 AM	#5
Hurricane Lost in Space Join Date: Aug 2002 Location: Ottawa, ON Age: 36 Posts: 82	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!") __________________ - 2000 Silvermist GT1

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09-06-2006, 10:23 PM	#4
mikep1987 GAGT - Newbie Join Date: Mar 2004 Location: South Amboy, NJ/Phoenix, AZ Age: 26 Posts: 27 Vehicle: 2000 Grand Am GT1	When I had a blown head gasket the oil looked fine, but the coolant looked like a chocolate shake.

09-07-2006, 08:57 AM	#6
Simpson36 GAGT - Newbie Join Date: Oct 2005 Location: Phoenix, AZ Posts: 13 Vehicle: 1999 Grand Am GT	I read somewhere that you can pull the heads with the exhaust manifolds attached.