Clackity Clackity? Cutlass? Alignment? Help?

[rfrye1]

I've owned my '98 Hunter H376 for 12 yrs. I have a persistent issue with knocking/"Clackity Clackity" at higher rpm. Usually about 2800 and higher. I've changed cutlass bearings, new shaft, new eng mounts. The knocking goes away after I spend $1000+ , but has always returned. What am I missing? I'm considering a 3 blade prop hoping it would balance better.

Again, what am I missing? You all have any suggestions? Ideas?

Thanks. Bob

 

[Ross]

You have been throwing money at a problem that you haven't identified. Cutlass bearing ought to last for a very long time, the shaft doesn't need to be replaced unless it has become scored. Engine mounts are pretty easy to inspect. Have you removed the engine cover and inspected everything while underway at speed?

 

[rfrye1]

Ross,

Yes. The sound is definitely coming from behind the engine. The propeller shaft aft. Of course hard to pin point. But where shaft passes thru hull and beyond.

 

[Ross]

How long is the shaft?

 

[Brett B]

I recently solved the same symptoms on my H31. The shaft was hitting the shaft log as the engine moved on its mounts. I re-aligned the engine and the problem was solved. Given what you have done I assume the engined was re-aligned but was it on the hard or just after launch. If so do it again after being afloat for a while and try to make sure the shaft is centered in the log.

 

[MrBee]

Bret b is correct. I have the same issue at certain rpms. I still haven't made tge adjustment to the motor mouts to get rid of noise but its on my list.