2014 Cobalt 220 Drive Noise

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bruced4
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2014 Cobalt 220 Drive Noise

Post by bruced4 » Wed Nov 25, 2015 1:29 pm

I have a 2014 Cobalt 220 with the 5.0L Volvo Penta and Alpha drive. When I take corners at around 4k Rpm there is sound coming through the hull that is best described as "whuh whuh whuh whuh". It is quite pronounced and reverberates through the entire boat. This has always happened since the boat was new. The dealer took it for a ride and says this is "normal oscillation" with the Alpha drive on this boat. I have had 3 alpha drives on various branded boats and never had anything but smooth performance at all Rpm's. I even tried a different prop and had the same issue. Anyone have a similar experience? Any ideas would be much appreciated!

jhnmdahl
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Re: 2014 Cobalt 220 Drive Noise

Post by jhnmdahl » Mon Nov 30, 2015 12:03 pm

It would have been nice for the dealer to at least tell you what was normally oscillating to cause the noise. Is it coming from the hull only in the rear where the outdrive is mounted, or from the whole hull? Is it worse when you're turning more sharply? If it's only at 4k rpm (and not at 3500 or 4500) it sounds a lot more like the engine/outdrive, but could be a hull characteristic that only happens at whatever speed corresponds to 4k rpm.
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bruced4
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Re: 2014 Cobalt 220 Drive Noise

Post by bruced4 » Tue Dec 01, 2015 8:22 am

The dealer initially said "there was definitely something going on back there" upon their initial test drive, but that they couldn't address it until Spring. I brought it back this year in the Spring and their story changed to "this is normal for the Alpha drive on this boat". They said it is not the boat, but the drive and how it interacts with the hull. The noise is coming from the drive, but reverberates through the hull. It seems so happen at all RPM's but is MOST apparent at 4K and in a hard turn. To me its almost as if the drive is not spinning concentrically, and that when stress is applied to the propeller in a turn, this out-of-round condition manifests itself as the "whuh, whuh, whuh" noise. Hope this helps clarify a little.

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Re: 2014 Cobalt 220 Drive Noise

Post by jhnmdahl » Tue Dec 01, 2015 10:50 am

It could be u joints or gimbal bearing, or even the propeller. I also wonder about the outdrive being slightly out of alignment with the engine. These are all easy to check, but putting the outdrive back on after checking is a little more time-consuming. I might press the dealer (the first guy you talked to who thought there was definitely something going on) to remove the outdrive and give at least these three things a quick look, and make sure the propeller's balanced.

I haven't heard of this being normal with other boats, and hope it's something they can resolve with yours.

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Re: 2014 Cobalt 220 Drive Noise

Post by bruced4 » Fri Dec 04, 2015 10:13 am

Thanks John. I think in the spring I will have the Volvo Penta rep take a ride with me. This is the only thing about this boat I don't love. Cobalt is a dream come true outside of this one annoyance.

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