Lou C
Supreme Mariner
- Joined
- Nov 10, 2002
- Messages
- 11,856
OK a few things I noticed:
the rust on the valve springs and heads, suggests water intrusion, besides the broke valve springs. I would think with that many valve springs broken (unusual in my experience with a 4.3) the engine may have been over-reved in the past. Is the boat over-propped?
water intrusion can come from those one piece manifolds (weren't they known for that, this has been commented on many times on this forum)
also, water intrusion can come from a bad head gasket, and head gasket damage that lets water in a cyl and in the oil, does not always show on a comp test. I had this same issue myself last year. I had 2 blown head gaskets letting water in but the comp test results were close to normal. So you should test the exhaust manifolds for leaks and look in the exhaust ports of both the manifolds and cyl heads for rust. I'd for sure crank it over with the plugs out and ignition disabled and check for water in the cyls. If so I'd try to pressure test the cooling system. I rigged up a dynamic test for combustion gas getting into the cooling water, sure sign of a blown HG.....watch what happens at the end of the vid when I shut it off......
https://www.dropbox.com/s/8lz4p4e7pdrtqr2/summer and fall 2016 232.MOV?dl=0
did a top end rebuild with a pair of reman heads and new gaskets, and center riser exhaust conversion:
https://www.dropbox.com/s/55j6h4dd1u8fv0k/IMG_2273.MOV?dl=0
the rust on the valve springs and heads, suggests water intrusion, besides the broke valve springs. I would think with that many valve springs broken (unusual in my experience with a 4.3) the engine may have been over-reved in the past. Is the boat over-propped?
water intrusion can come from those one piece manifolds (weren't they known for that, this has been commented on many times on this forum)
also, water intrusion can come from a bad head gasket, and head gasket damage that lets water in a cyl and in the oil, does not always show on a comp test. I had this same issue myself last year. I had 2 blown head gaskets letting water in but the comp test results were close to normal. So you should test the exhaust manifolds for leaks and look in the exhaust ports of both the manifolds and cyl heads for rust. I'd for sure crank it over with the plugs out and ignition disabled and check for water in the cyls. If so I'd try to pressure test the cooling system. I rigged up a dynamic test for combustion gas getting into the cooling water, sure sign of a blown HG.....watch what happens at the end of the vid when I shut it off......
https://www.dropbox.com/s/8lz4p4e7pdrtqr2/summer and fall 2016 232.MOV?dl=0
did a top end rebuild with a pair of reman heads and new gaskets, and center riser exhaust conversion:
https://www.dropbox.com/s/55j6h4dd1u8fv0k/IMG_2273.MOV?dl=0
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