Caught that funny drivetrain sound, here's a sound clip...

[IDBoating]

In various threads, we've discussed funny sounds from the drivetrain when our boats are heavily ballasted. Turns out my 9YO son captured the sound a few days ago on his iPod. Here's the link:

Click here to listen

It doesn't seem this loud on board, the microphone on the iPod was amazingly sensitive to it. Plus he held it right down near the floor.

This is with the transmission just barely engaged, i.e. at engine idle but the prop is rotating. When you hear the sound stop, that's when I pulled the throttle completely to neutral (you can hear the "click" of the throttle lever right when the sound stops) leaving the engine running but the transmission disengaged. If we back off the throttle lever to the "click" and then reengage, I cannot ever remember it starting up again.

This occurs when the boat is ballasted and we're slowing down to go back and pick up a downed surfer. It's never happened when the boat was level. I have checked all fluid levels in the engine, transmission, and v-drive. I've looked for things rubbing on the propshaft or the front of the v-drive. There's nothing on the outside of the running gear. ~120 hours on the boat, the first 15 by the dealer and the rest by us this summer so we know its entire history. No abuse, we've never hit anything. There is no vibration at any speed or RPM's. It's purely acoustic.

Anyone have any ideas?

[boatwakes]

It's your prop "singing" and means you're over-pitched for the weight. Whenever we repower a boat if it "sings" at idle it means it's over-pitched and will never attain full engine rpm. Get another prop for surfing with less pitch and the sound will disappear (usually 1-2" less pitch).

[talltigeguy]

It's your prop "singing" and means you're over-pitched for the weight. Whenever we repower a boat if it "sings" at idle it means it's over-pitched and will never attain full engine rpm. Get another prop for surfing with less pitch and the sound will disappear (usually 1-2" less pitch).

How does a prop sound at idle tell you that it can never reach full RPM?

WA - you got the 1235 Acme?

I don't know what the sound is, but it sounds horrid.

[thtrog]

Last year you stated there was a vibration on takeoff...did you ever find the cause? The amount of ballast you are loading and documenting is not "normal use". I've been on Lot's of boats and have never heard a sound like that. I believe I would get it to my local dealer ASAP.

[Timmy!]

Have you checked your propshaft alignment? Maybe it's not a big deal when unloaded but once you weight it down a small amount becomes a lot? That sound would freak me out!

[Duncan]

In other threads, I have mentioned that I too had an occasional odd sound. But it was not that thrumming sounds. I have a light tickticktick at the V.

That sounds strange for sure

[Joeprunc]

Just throwing it out there...I was on a Malibu the other week and it made a noise like that in idle speeds. I couldn't tell where it was coming from, but the boat owner said a mechanic told him that noise was a bearing in the alternator going out. It went away at higher RPMs and dissipated in neutral. After reading BoatWakes response I feel like the Bu owner may not be right.

I can't recall BoatWakes actual name, but he has contributed a lot of very insightful information on this site. I'd give it a try. Either re prop, or remove the weight and see if it continues.

[duffymahoney]

Mine makes a weird tick sound when I idle around in the marina. No idea what it is.

[IDBoating]

It's your prop "singing" and means you're over-pitched for the weight. Whenever we repower a boat if it "sings" at idle it means it's over-pitched and will never attain full engine rpm. Get another prop for surfing with less pitch and the sound will disappear (usually 1-2" less pitch).

Thanks for the feedback. I wouldn't call this "singing". It's a periodic thing rather than a sustained sound.

I'm running the Acme 1235 at their specific recommendation, as are others with 24Ve's. My WOT RPM's are 5200, just a bit higher than PCM would like (their target is 5000), so I don't think this is a case of an overpitched prop since I'm actually able to go a bit beyond recommended RPM's.

[IDBoating]

Last year you stated there was a vibration on takeoff...did you ever find the cause?

Once I removed the stock 537 prop and replaced it with the 1235, I've never felt that vibration ever again. It only occurred under WOT acceleration from a dead stop, so I've chalked it up to cavitation. Might instead be an out-of-balance prop, but in any case it's gone.

The amount of ballast you are loading and documenting is not "normal use". I've been on Lot's of boats and have never heard a sound like that. I believe I would get it to my local dealer ASAP.

I would, but it's extremely intermittent. It might happen once or twice in eight full hours of engine use on a given day. Some days it doesn't happen at all. It also is related to propshaft rotation (i.e. goes away when the transmission is disengaged) so it's not something you can diagnose on the trailer. You have to be in the water. I LIVE on the water, whereas the nearest Tige dealer is ~15 miles away. Letting it sit in his shop for an extremely intermittent problem that cannot be demonstrated on the trailer doesn't sound like a path to a solution - they'd probably just start going through everything at my expense. While it's well within warranty, if they "don't find anything" I'll get a big labor bill.

That's why I'm posting it here. I'm hopeful someone will hear it and recognize it and have some suggestion on where to start looking.

[IDBoating]

Have you checked your propshaft alignment? Maybe it's not a big deal when unloaded but once you weight it down a small amount becomes a lot?

I'm thinking along the same lines. What's interesting is how I can get it to go away by taking it out of gear for a moment. When I reengage the transmission, the sound doesn't come back. But if I leave it engaged, the sound continues even though I'm slowing down and turning 180 degrees, etc. That makes me think something is "loaded up" and stays that way until the stresses are relieved out of the drivetrain, after which it can resume normal operation.

The other odd, impossible-to-diagnose part is that it is SO intermittent. Like I said above, it might happen 0-2 times in eight hours of engine operation. Some days it never happens and I never even think about it. I have not been able to find a pattern that consistently causes it, though clicking back to neutral makes it go away 100% of the time.

[IDBoating]

In other threads, I have mentioned that I too had an occasional odd sound. But it was not that thrumming sounds. I have a light tickticktick at the V.

My steering cable was rubbing on the stuffing box occasionally, causing a light ticking sound when the propshaft was turning. Loose zipties fixed that. This is obviously different.

[IDBoating]

Jthe boat owner said a mechanic told him that noise was a bearing in the alternator going out. It went away at higher RPMs and dissipated in neutral.

This sound seems to be coming from the transmission/v-drive area, though I suppose anything is possible. One thing I've considered is taking all the hardware out of the rear seat section and driving around trying to cause it. If and when it occurs, leave the boat in gear and take up the seat so I can narrow it down to the exact component. Trouble is, it can go 8+ engine hours without ever doing it.

Either re prop, or remove the weight and see if it continues.

See my response to him above regarding the prop. As for weight, I've never had it happen when not ballasted so I believe the weight is related in some way.

One idea I mentioned in another thread was that the drivetrain is designed to operate while mostly level. When we ultra-ballast these boats, the drivetrain is sitting at an angle. I wonder if the fluids in the tranny or v-drive are thus at an angle, and some components that are supposed to be within the lubricant bath are sitting above it. I may try calling PCM about that.

[IDBoating]

Mine makes a weird tick sound when I idle around in the marina. No idea what it is.

As mentioned above, check your steering cable for wear on its sheath. Mine was rubbing on the stuffing box once in a while, causing an RPM-related ticking sound and wearing on the sheath.

[Joeprunc]

This sound seems to be coming from the transmission/v-drive area, though I suppose anything is possible. One thing I've considered is taking all the hardware out of the rear seat section and driving around trying to cause it. If and when it occurs, leave the boat in gear and take up the seat so I can narrow it down to the exact component. Trouble is, it can go 8+ engine hours without ever doing it.



See my response to him above regarding the prop. As for weight, I've never had it happen when not ballasted so I believe the weight is related in some way.

One idea I mentioned in another thread was that the drivetrain is designed to operate while mostly level. When we ultra-ballast these boats, the drivetrain is sitting at an angle. I wonder if the fluids in the tranny or v-drive are thus at an angle, and some components that are supposed to be within the lubricant bath are sitting above it. I may try calling PCM about that.

I was thinking that too, it may be worth calling PCM or Velvet. But I would think the noise would worsen when accelerating or surfing as the angle would only increase. But maybe the surrounding noises of the motor, exhaust, radio, water, mask it while at speed. I wonder if Ragboy has experienced this as it looks like his boat is absolutely loaded with weight.