Blown headgasket??? - Team Camaro Tech
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post #1 of 10 (permalink) Old Apr 5th, 15, 08:01 AM Thread Starter
Gary
 
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Unhappy Blown headgasket???

How do I tell if I blew a head gasket or just an intake gasket?
There is coolant in the oilpan and white smoke out the exhaust and steam coming out the oil breather. It seems to run fine and idle ok. I'm confused and think a new head gasket, proper bolt installation, and intake gasket may solve the problem or do I just need a new intake gasket? It is a 1968 L78 396/375 iron head motor.
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post #2 of 10 (permalink) Old Apr 5th, 15, 09:41 AM
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Re: Blown headgasket???

IMHO it's highly unlikely that coolant is being sucked into the combustion chamber thru a bad intake gasket. Pull all the plugs and when you fine one that is completely white that is your bad cylinder. Do a cylinder leakage test on it with the radiator and oil caps off. I think you will find air pressure coming out the radiator cap.

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post #3 of 10 (permalink) Old Apr 5th, 15, 10:50 AM
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Re: Blown headgasket???

To get to the head gasket you have to remove the manifold and expose the intake gaskets so.....I would recommend that first.
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post #4 of 10 (permalink) Old Apr 5th, 15, 10:54 AM
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Re: Blown headgasket???

Anti freeze is really bad for all your bearings. I'd get it figured out asap. You'll have to pull the intake any way. Start there.
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post #5 of 10 (permalink) Old Apr 5th, 15, 11:25 AM
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Re: Blown headgasket???

While your doing the job drain the oil and remove filter leave the plug out and let it drain to nothing. Anti freeze is a bearing killer get some butyl celosolve and put in with the fresh oil and filter. Run it a while and drain completely well then fresh oil and filter change again at 500 mi. Butyl celosolve is a glycol ether and will get rid of the antifreeze . Make sure you are very careful with it it is highly carcinogenous and is absorbed quickly through the skin, long gloves and a face shield . Alex
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post #6 of 10 (permalink) Old Apr 5th, 15, 08:32 PM
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Re: Blown headgasket???

Quote:
Originally Posted by garyss396 View Post
How do I tell if I blew a head gasket or just an intake gasket?
There is coolant in the oilpan and white smoke out the exhaust and steam coming out the oil breather. It seems to run fine and idle ok. I'm confused and think a new head gasket, proper bolt installation, and intake gasket may solve the problem or do I just need a new intake gasket? It is a 1968 L78 396/375 iron head motor.
Coolant in the oilpan? Coolant out the tailpipe? Could be more than a gasket. Hope it isn't a head or a block issue.
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post #7 of 10 (permalink) Old Apr 5th, 15, 10:14 PM
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Re: Blown headgasket???

that could be a blown head gasket if it is blown in just the rite spot. But is sounds more like a crack in the head between a water jacket and a valve I would pull both heads and have them both checked no sense in playing around I can Guarantee you it is not a simple fix.
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post #8 of 10 (permalink) Old Apr 6th, 15, 11:54 AM
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Re: Blown headgasket???

Have the heads mag'd and pressure tested. You could have a pinhole in the valve area or just a weak casting that has worn from all the years of coolant running though it. When you reassemble it, just fill the coolant with plain water for your initial drive test. Then you can drain the rad and then open the 2 block coolant bolts and empty it all then refill with a 50/50 mix.

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post #9 of 10 (permalink) Old Apr 6th, 15, 12:19 PM Thread Starter
Gary
 
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Cool Re: Blown headgasket???

Thanks for the information guys. I'll pull both heads and have them checked. Not sure what is going on so I'll just hope it is not too bad.
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post #10 of 10 (permalink) Old Apr 6th, 15, 01:29 PM
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Re: Blown headgasket???

Gary, I've never blown a head gasket on a BBC (L78 included) but that is a substantial engine that deserves proper inspection and repair. I suggest that you buy, borrow or rent two tools: a shop crane and engine stand. Pull your engine and be prepared for a proper repair, that may well involve machine work.

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