New Alpha 1 Gen 2 outdrive - noise at 3000 rpms

JJJ

Petty Officer 2nd Class
Joined
May 12, 2005
Messages
158
96 Cobalt 4.3L
I just installed a NEW MERC Alpha 1 Gen 2 outdrive and took it out for it's maiden voyage. At 3000 rpms I get this whine/drone, goes away at 2800 rpms and 3200 rpms, noise shuts off like a switch was thrown when out of that narrow rpm range.

I put a few hours and about 25 miles on it, came home and drained the oil. Very little if any thing on the magnet, a few small slivers.

Could it just be the outdrive still just needs broken in? Or is there something more to worry about? It seemed to be getting quieter as time went on, but maybe I was just becoming tone deaf to it??

Could it just be a resonant frequency noise due to the prop?
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,468
Re: New Alpha 1 Gen 2 outdrive - noise at 3000 rpms

Ayuh,.... Could be,... Maybe,... Possibly,... Ya might be onta somethin'....

Donno... I'd Run it... ;)
 

Failproof

Petty Officer 1st Class
Joined
Sep 26, 2011
Messages
273
Re: New Alpha 1 Gen 2 outdrive - noise at 3000 rpms

Breaking in an outdrive sometimes you get odd harmonic disturbances as the gear sets wear in. If it starts growling or clunking I would be concerned. If it gets noisier or across a broader range I would be concerned. I used to tell my customers to treat a new outdrive as if you were breaking in a new motor for the first 10 hours. Then bring in for free drain, inspect, and refill. After the drain and refill they could beat them like before and break like before. Or be nice and probably never see me for a new outdrive
 

JJJ

Petty Officer 2nd Class
Joined
May 12, 2005
Messages
158
Re: New Alpha 1 Gen 2 outdrive - noise at 3000 rpms

Thanks, I feel a bit better. That is exactly what it sounds like too, similar to a rear end that the pinion depth isn't just perfect.

I can't do a proper long breakin, as I'm taking it to the Keys in 2 weeks. However I almost never run over 3500 except for very short bursts. Unfortunately, I do cruise at the 3000 range :(

Hopefully the water will be flat instead of bad wind chop, then I can cruise at what ever rpm I want to.

While the hull prefers over 40 mph, my pocket doesn't really enjoy using the 4 bbl quite as much :)
 
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