Thread: Random tapping
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  #37   IP: 107.77.97.107
Old 09-27-2019, 12:31 PM
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Quote:
Originally Posted by ndutton View Post
I don't think the head gasket or exhaust valve hanging open is off the table yet. There is minimal combustion pressure on the manifold when the valves are seating properly. Exhaust gases are merely pushed out by the piston on the exhaust stroke (note: well AFTER combustion has occurred). For high pressure combustion gases to escape it has to happen at TDC which is when the valves are supposed to be sealed. This is where the compression test may point us in a direction.
I think Neil(as usual) was on to this back in post #28.

Also, never rule out that more than one thing can go wrong at the same time. It's an old engine.
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