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Old 01-30-2019, 12:43 AM
deantheking101 deantheking101 is offline
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Exhaust Manifold Corrosion

I have a 1975 C30 with a large deal of corrosion on the most forward manifold stud to the point where it is dropping into the air intake. I took some pictures before and after i cleaned it up with a wire brush.

Second the motor when it gets hot after running for 3+ hours starts to smoke pretty badly. I believe mostly out of the tube where you add the oil. However some smoke also coming out of the manifold also. The temp guage does not work......

I did a compression test today. The most forward cylinder was 50 (i checked it twice) the other 3 were all 80-85.

I spoke with Ken at Moyers and sent him this same email and will be talking to him soon but wanted to get some other opinions on the best course of action. This summer i plan on doing a inner island 3-4 week trip in Hawaii and want well running motor. Buying a rebuilt one is a option.

Thanks in advance.
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Old 01-30-2019, 07:48 PM
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Al Schober Al Schober is offline
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First, you may have a slight leak where that manifold stud screws into the block. I'd try removing the manifold then cleaning and reseating all 3 studs. I'd install a new stud/nut and trash the rusty ones. While you've got them out, check the wall thickness of the block at all 3 studs - see what you've got left. This is low cost - might not even need a new manifold gasket but I'd get one just in case.
Second, compression. Those numbers and the smoke suggest to me worn piston rings. Don't know the history of the engine but it could be time for new rings - they DO wear out. May not be a big deal - bearings and the pistons themselves may be fine.
If you don't have the Moyer Manual, buy one. Details engine disassembly, overhaul, reassembly. Basically, you're going to remove the engine from the boat, remove transmission, head, and oil pan. This will allow you to remove the pistons, replace the rings, then reassemble. Based on my experience, you will find NO ridge at the tops of the cylinders worth reaming. Reassemble with new rings and you could be done - good for another 20 years. Also recommend changing the aft transmission oil seal.

Last edited by Al Schober; 01-30-2019 at 07:54 PM.
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Old 01-30-2019, 09:18 PM
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ndutton ndutton is offline
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Part of the smoke problem may be the orientation of the backfire flame arrester. However, if there is budget for a Moyer rebuilt, you can't go wrong.
1977 Catalina 30
San Pedro, California
prior boats 1987 Westsail 32, 1970 Catalina 22
Had my hands in a few others
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Old 01-31-2019, 07:48 AM
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If you have the cash, I wouldn't hesitate for a second to get a Moyer rebuild.
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Old 01-31-2019, 10:15 AM
jwmurphy jwmurphy is offline
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General question:
I noticed in Dean's pictures that the scavenger tube appears to be cut/disconnected. Is this a fuel safety concern?
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