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Old 12-14-2024, 03:11 PM   #1
65C10ED
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Blown Head Gasket or No?

Thinking I was dealing with a blown head gasket on my 350 small block chevy engine, I removed the intake manifold and this is what I found. Do the intake gaskets usually get distorted like that with a blown head gasket? Or is it possible that the failure of the intake gasket is what caused the mixing of oil and coolant?
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Old 12-14-2024, 04:18 PM   #2
AcampoDave
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Re: Blown Head Gasket or No?

Is it too late for compression test?
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Old 12-14-2024, 04:21 PM   #3
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Re: Blown Head Gasket or No?

Is there coolant in the cylinders? A loose or warped or otherwise poorly sealed intake gasket can result in coolant getting into the oil supply.

Possible the intake bolts backed out and left things loose enough to move around. Between the angled bolts and weight of the intake + carb + dizzy, the bolts can be loose and things will still stay pretty much in place. Loose enough to leak, tight enough to seem fine.

Compression check should tell if there is a blown head gasket.

BTW - if you are chasing a pesky exhaust leak noise, don't overlook the exhaust crossover in the intake.
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Old 12-14-2024, 05:21 PM   #4
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Re: Blown Head Gasket or No?

Looks like a FelPro gasket, and they usually don't tear apart like that. It almost looks like the intake wasn't cut to match a deck/head surface during a rebuild. It's super hard to diagnose from a picture but take a hard look at the gasket around the coolant flow ports on either end. The elongated bolt hole to the right of the crossover makes me wonder if the gasket was moved during installation...not uncommon if someone's not careful dropping the manifold in place.

Clean up the gasket mating surfaces on the head, block, and intake and set the intake in dry with no gasket. Loosely install a few bolts for positioning, then look at the front of the block/heads and see what kind of gap you have and if the intake mating surface is parallel to the head mating surface. Any mismatch would be an indication of a problem...although I would have expected you'd have had a major vacuum leak as well.

However, I don't see that as an indication of a blown head gasket. I mean, you're 90% of the way there - pull the heads and see Gives you a chance to also set the correct quench by using the right thickness gasket.
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Old 12-18-2024, 10:50 PM   #5
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Re: Blown Head Gasket or No?

Since Chevy small blocks don't blow head gaskets I wouldn't worry about that. Fel pro makes a few different intake gaskets. Some have bigger port openings and some have smaller openings for the stock heads. I always forget the numbers but it looks like your gasket has bigger port openings and isn't sealing like it should.
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