Leaking head gasket
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From: Fort Rucker, AL
Leaking head gasket
Is it possible to leak oil from the head gasket, say like from the vicinity of the oil return (jet?). I've looked and looked and the only thing that it seems to be is coming from the head gasket. I've always associated a leaking head gasket with water.
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From: Montana
Oil return jet?? I'm confused.
In the 390 there is an oil passage from the block thru each head gasket to feed oil to the rocker arms. This oil passage leaves the block, joggles over to a head bolt (second from front or second from rear on head bolts closest to intake manifold), then goes up along the head bolt, then thru an angled passage thru the head to a rocker arm stand, then up inside the stand to the rocker shaft.
So it is possible to be leaking oil out the head gasket, but the oil leak would be under the intake manifold.
In the 390 there is an oil passage from the block thru each head gasket to feed oil to the rocker arms. This oil passage leaves the block, joggles over to a head bolt (second from front or second from rear on head bolts closest to intake manifold), then goes up along the head bolt, then thru an angled passage thru the head to a rocker arm stand, then up inside the stand to the rocker shaft.
So it is possible to be leaking oil out the head gasket, but the oil leak would be under the intake manifold.
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From: Fort Rucker, AL
I can't remember exactly what the guy said but I know there's no such thing as an oil jet. silly me. So you are saying the oil leak could be fixed by replacing the head gasket? Or could I dob some RTV in there and hope for the best? The leak is in the back, I failed to mention that.
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From: Montana
Leak in the back makes me think of valve cover or rear intake manifold gasket (along the top of the block). The rear of the head gasket has a water passage thru it, so should not be leaking oil back there.
Steam the engine off real well at the car wash. Run the engine and look for leaks. Gooping silicone from the outside never works very well.
If it was me I would replace the valve cover gaskets just to do it. Clean the covers off real well where the new gasket will lay.
If this doesn't fix the leak then go for the intake manifold. Use silicone for the block end seals - lay a thick bead at least 1/4 inch thick. Put silicone around the water passages at the front of the heads too. If you've got a stock cast iron manifold it helps to have 2 people to lift it off and back on - a good time to swap to an aluminum intake. Suggest Edelbrock performer RPM.
Hope this helps.
Steam the engine off real well at the car wash. Run the engine and look for leaks. Gooping silicone from the outside never works very well.
If it was me I would replace the valve cover gaskets just to do it. Clean the covers off real well where the new gasket will lay.
If this doesn't fix the leak then go for the intake manifold. Use silicone for the block end seals - lay a thick bead at least 1/4 inch thick. Put silicone around the water passages at the front of the heads too. If you've got a stock cast iron manifold it helps to have 2 people to lift it off and back on - a good time to swap to an aluminum intake. Suggest Edelbrock performer RPM.
Hope this helps.
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From: Fort Rucker, AL
Guess what? I had to put a quart of my favorite oil in today because it leaked down. I also have a small leak in the front of the motor but fairly insignificant, meaning it's not making a mess when I park. I gave the quart and I stood there and watched a small drop of oil run from the intake, down the head gasket, and slither down to the fuel pump. I have to believe the same thing is happening on the back, just on a grander scale, the cork on the bottom didn't mesh with the paper on the sides or something.
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