new qm15 Yanmar installed in June 2006 , when motor is running no knocking and no kocking sound no vibration this motor came with new transmission. when put in foward or reverse knocking sound louder at higher rpm . single michigan two blade propeller Q: could this be the stuffing box , or the Shaft log Q: what is the life of each
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Had the same problem years ago...
Problem is that the engine isn't aligned properly in the shaft log and the propeller shaft is banging against the sides of the shaft log. This only happen when the engine is in gear and thus vibrating more. You haven't by chance added a dripless stuffing box? This will exasperate the problem as the old fashioned stuffing box adds kind of a pilot bearing to the propeller shaft. Small diesels vibrate a'lot. Are the motor mounts in good shape and tight? This can be confirmed by shifting the position of the running engine from side to side and up and down. Use a small crow bar and be careful. It won't take much movement. Good luck.
Problem is that the engine isn't aligned properly in the shaft log and the propeller shaft is banging against the sides of the shaft log. This only happen when the engine is in gear and thus vibrating more. You haven't by chance added a dripless stuffing box? This will exasperate the problem as the old fashioned stuffing box adds kind of a pilot bearing to the propeller shaft. Small diesels vibrate a'lot. Are the motor mounts in good shape and tight? This can be confirmed by shifting the position of the running engine from side to side and up and down. Use a small crow bar and be careful. It won't take much movement. Good luck.
Knocking could be loose sink
We have a 40.5 that had a knocking sound when ever we were in gear. It turned out that a zinc had broken and was hitting the underside of the hull every time the shaft rotated. It was a fairly new zinc that may have been installed incorrectly by our divers.
We have a 40.5 that had a knocking sound when ever we were in gear. It turned out that a zinc had broken and was hitting the underside of the hull every time the shaft rotated. It was a fairly new zinc that may have been installed incorrectly by our divers.
Tim.
Wouldn't that loose sink slow you down too?
Harold, do what Landsend said. I recommend that you learn to align the engine yourself. Even marine mechanics often don't get it right.
Wouldn't that loose sink slow you down too?
Harold, do what Landsend said. I recommend that you learn to align the engine yourself. Even marine mechanics often don't get it right.Cutlass Bearing
Could it be the cutlass bearing? I'm having mine replaced soon for similar bad sounds.
Could it be the cutlass bearing? I'm having mine replaced soon for similar bad sounds.
most likely
the engine wasn't aligned right when it was installed. I installed my engine this summer and aligned it myself and it knocked bad. I re-aligned it twice and still knocked. I took it to the yard and they aligned it, straighted the prop and it still knocked. On their second attempt to align it, the knock is mostly gone.
the engine wasn't aligned right when it was installed. I installed my engine this summer and aligned it myself and it knocked bad. I re-aligned it twice and still knocked. I took it to the yard and they aligned it, straighted the prop and it still knocked. On their second attempt to align it, the knock is mostly gone.
Check the motor mounts too
Yanmar motor mounts are not things that last forever. While doing the alignment or having it done inspect the motor mounts. Depending on your engine I think they are about 250 to 350 a piece.
Yanmar motor mounts are not things that last forever. While doing the alignment or having it done inspect the motor mounts. Depending on your engine I think they are about 250 to 350 a piece.
knocking
is this knocking under way? I once left the ladder in the water and it did just that, drove me nuts, I thought something was caught on the shaft.
is this knocking under way? I once left the ladder in the water and it did just that, drove me nuts, I thought something was caught on the shaft.
think it is an alignment problem alright
This has been covered. And by the way $250.00 for a motor mount? Torrensen Marine charged me $65.00 for mine when I had the shaft replaced. Maybe they pityed me due to the rest of the job. Lugeman
This has been covered. And by the way $250.00 for a motor mount? Torrensen Marine charged me $65.00 for mine when I had the shaft replaced. Maybe they pityed me due to the rest of the job. Lugeman
Hate to add another thing to check...but....
I had a similar sound on my H33 last year. I had just installed a "dripless" shaft log and that was the culprit. All I had to do was "burp" it and the noise disappeared.
I had a similar sound on my H33 last year. I had just installed a "dripless" shaft log and that was the culprit. All I had to do was "burp" it and the noise disappeared.
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