Loud Harmonic Hum Under Power

[RON CARTER]

since we purchased AZGARD last april we were driven crazy by this sound at 1400-1900 rp and have learned that two p.o. had same problem. Sept this year we replaced original M-25 universal diesel with a NEW universal XPB 25 and much to our horror we have the very same noise at 1400-2000 rpm. The only parts we did not replace were shaft and prop, 16 inch x 10 pitch r.h. fixed 3 blade.......... Can this hum /whine noise somehow result from prop turbulence between prop and hull ??? Local dock experts suggest changing pitch very slightly may help which I can do as we only attain 3000 rpm peak against 3200.
Has anyone had similair noise on ERICSON 35-3 AND HOW DID YOU CURE???

 

[Loren Beach]

Your boat is not too different from mine, at least so far as powering.
I have a Universal M25XP with about 1600 hours on it.
I get some harmonic vibration at around 1800 or so. Nothing too bad, but the hatch vibrates along with the stove top.


Have you checked the cutlass bearing for wear, and had the shaft trued? Also rebalance the prop. And, check the allignment of the shaft and strut.
Back to basics -- do a careful allignment of the engine. How's the coupling? We replaced the original one right after we bought the boat; prior owner had not maintained the set screws and drove around with the shaft loose.

How are the engine mounts? Were they changed out when the new engine was installed?

Best of luck in solving your hum and whine.

Loren in PDX
Olson 34 #8

 

[RON CARTER]

Thanks for your help, Yes the cutlass bearing was good, and we did install new coupling, and new engine mounts . On spring 2004 haul out will check prop and strut. We did have professional marine mechanic do installation and alignment who h
as experience with repower using same engine. Thanks Again