Noise above 2600 rpm

[crquisto]

I have a rubbing or weird grinding noise from my port side when in gear with rpm above 2600. It sounds almost like wood on metal. I hit a log pretty hard a couple of weeks ago and subsequently discovered a water leak around the hose over my shaft log. When I got that fixed, I took off with the engine compartment opened up and my son watching for anything leaking or vibrating. None was noted, but we heard the new noise as soon as I advanced rpm above 2600 while under way. It does not make the noise if in neutral. My diver conducted a thorough inspection of the underside while scraping the bottom and no problems were noted. Does anyone have an idea where I should start looking, or should I just call my mechanic and wait the month before he'll be able to look at it?

[mjk1040]

My guess would be something is not true in the output shaft from the transmission to the prop. Shaft log maybe. If access is good one could use a mechanics stethoscope and put on the shaft log and see if u can pin point the noise. The other possibility could be the strut bearings could be bad after the log hit. U could uncouple the prop shaft from transmission and then run transmission up to 2000 rpm's to eliminate the engine and transmission. U would then know its after the transmission. Good Luck!

[John Easley]

Source of the post My guess would be something is not true in the output shaft from the transmission to the prop. Shaft log maybe. If access is good one could use a mechanics stethoscope and put on the shaft log and see if u can pin point the noise. The other possibility could be the strut bearings could be bad after the log hit. U could uncouple the prop shaft from transmission and then run transmission up to 2000 rpm's to eliminate the engine and transmission. U would then know its after the transmission. Good Luck!

Agreed. ...on the probable issue and on the diagnostic approach.

[throwback2]

I would believe that if you hit something like that ,the boat should be pulled out of the water and check the shaft and rest of the hardware.

[crquisto]

Thank you for all your inputs. Throwback2, I had my diver conduct a thorough underwater inspection and he said everything there looked good. We have no vibrations that would indicate a shaft or prop issue, so I had my mechanic ride along yesterday and he identified the noise as a bad coupler and probably a transmission bearing. Those may not be related at all to my log strike, but the noise could not be heard up top with everything closed up. I only discovered the noise because I was running opened up to inspect for a fixed water leak around my shaft log. We'll be pulling the transmission as soon as my mechanic has time. Bummer, but hopefully back in business for fall cruising. Thanks again.

[crquisto]

Sorry I didn’t follow up on this to close it out earlier. Mechanic was able to lift the engine on straps to slide it slightly forward and access the tranny. Found the coupler (I think that’s what it’s called - looks sorta like a clutch plate without all the pads) had disintegrated. The tranny operated smoothly by hand with engine and drive shaft disconnected. Replaced the coupler, slapped it back together and all seems well.