Mercruiser 3.0 tks noise at idle or no wake speed

[Nhboater89]

I have a 2006 bayliner 195 with mercruiser 3.0 tks alpha one gen 2. Have an unusual noise that can be heard at idle or in gear no wake speed. Comes and goes it is not constant. I’m from New Hampshire so I can best describe it as it sounds like a loon is in the engine bay. I’m a Honda master mechanic by trade but I can’t seem to correlate this noise to anything in the automotive realm. Try not to worry too much about the noise but I can’t seem to help myself. If it seems to ring a bell with someone feel free to chime in. Attached video hope it uploads.

 

[Alumarine]

Welcome.
All I can suggest is taking the drive belts off and see if the noise is still there?

Not that it has anything to do with the noise but what's with the loose black wire with the ring terminal at the back of the motor?

 

[Nhboater89]

It’s definitely a starting point I’ll just have to keep an eye on the temp gauge as the water pump won’t be operating.

As for the black wire with terminal ring that’s another great question I suspect it’s a ground but it doesn’t look like it has an obvious home in and around that location I believe it’s part of main wiring harness. It is folded back and taped the the harness

 

[Scott06]

It’s definitely a starting point I’ll just have to keep an eye on the temp gauge as the water pump won’t be operating.

As for the black wire with terminal ring that’s another great question I suspect it’s a ground but it doesn’t look like it has an obvious home in and around that location I believe it’s part of main wiring harness. It is folded back and taped the the harness

I would check the accessories by disconnecting the belts as well. Might be a gimbal bearing, does changing the drive or steering angle make any difference?

Its typical to find black wires with ring terminals in the engine harness that are unused. Mine had one as well. Seems like they may prep the harness for other options or configurations that your engine may not have

 

[Nhboater89]

I will give that a try as well and see if the noise goes away or changes pitch. The boats 2 hours away at the campground I stay at but I plan on bringing my stethoscope and poke around when I’m out on the water. Am I correct in saying the gimball is always spinning regardless whether the boat is in neutral or in gear because the actual gear is in the lower unit just before the prop?

 

[Alumarine]

Am I correct in saying the gimball is always spinning regardless whether the boat is in neutral or in gear because the actual gear is in the lower unit just before the prop?

Yes, that's correct.

 

[Scott06]

Am I correct in saying the gimball is always spinning regardless whether the boat is in neutral or in gear because the actual gear is in the lower unit just before the prop?

yep as stated the driveshaft, gimbal bearing, drive input shaft and vertical driveshaft are turning all the time the engine is running. On an alpha onky the propshaft doesn’t turn when in neutral

 

[QBhoy]

As above…but also wondering what oil you have in the gear lube tank ?

 

[Scott06]

As above…but also wondering what oil you have in the gear lube tank ?

I was thinking the same not merc hi perf lube

 

[Bt Doctur]

I heard something like that, it was the hollow pvc fitting causing the whistle

 

[Nhboater89]

As above…but also wondering what oil you have in the gear lube tank ?

Boat was new to me last year so I’m not sure. I changed it to the quicksilver high performance sae 90 blue stuff at the end of season. I’m keeping an eye on it because it appeared there was water or a good amount of condensation in there by end of season.

 

[Nhboater89]

I heard something like that, it was the hollow pvc fitting causing the whistle

Are you talking about the pcv or pvc wasn’t sure if that was a typo

 

[Bt Doctur]

Whatever you call that thing in the valve cover