Engine/Outdrive "Squeal" - Maxum Boat Owners Club

kt_maxum · 03-14-2021, 03:49 AM

Hi All,

I'm hearing a "squeal" from my engine (or perhaps the sterndrive) while underway. It sounds like a worn belt, however it doesn't happen when the engine is throttled up but not in gear. Once in gear, it happens at about 2,500 rpm and 3,200 rpm. If I speed up or slow down, it goes away, but I hear it consistently as I speed up or slow down.

Could this be a leg/sterndrive issue? A bearing of some kind?

I have a single 496 Mercruiser with a Bravo 2 outdrive.

Thanks,
Ken

mmwjr · 03-14-2021, 12:51 PM

Does the noise change when you steer side to side? If so it’s the gimbal bearing.

jparsons121 · 03-14-2021, 03:08 PM

If it’s truly is only when in gear, I suspect that it’s in the lower unit.
From the flywheel back until the clutches in the drive, you do have a gimbal bearing as well as U joints, but those all spin at engine speed wether in gear or not.

I’d start by verifying that the belt tension is correct and belt is in good condition.

mmwjr · 03-14-2021, 04:24 PM

Quote:

Originally Posted by jparsons121

If it’s truly is only when in gear, I suspect that it’s in the lower unit.
From the flywheel back until the clutches in the drive, you do have a gimbal bearing as well as U joints, but those all spin at engine speed wether in gear or not.

I’d start by verifying that the belt tension is correct and belt is in good condition.

While I agree with all this sometimes the gimbal bearing will get louder when additional load is applied. I.e. being in gear.

kt_maxum · 03-14-2021, 06:00 PM

The noise changes when I make small adjustments to the throttle (up or down). I haven't checked if it changes when I steer side to side, but will definitely check that.

I'll check the belt tensions and belt condition as well.

Thanks very much!

mmwjr · 03-14-2021, 07:45 PM

Quote:

Originally Posted by kt_maxum

The noise changes when I make small adjustments to the throttle (up or down). I haven't checked if it changes when I steer side to side, but will definitely check that.

I'll check the belt tensions and belt condition as well.

Thanks very much!

Also try trim up and down.

jro10 · 03-15-2021, 03:56 AM

Definitely check the condition/tension of the belts. We had a similar noise, and after looking into all sorts of possible sources, we found that one of the belts was slightly glazed. Simple change of the belt solved the problem. Your solution may not be that easy (our noise started at about the same RPM as yours, but it stayed constant as speed increased or when steering - basically as load increased), but worth at least checking before you dig into more complex solutions. Good luck!

kt_maxum · 03-15-2021, 04:03 AM

Thanks I'm hoping it's just a belt issue (except I would expect to hear the belt issue when I rev the engine out of gear, but I don't). I checked it today and if feels a bit loose, although I'm not certain how much tension should be on it. I'm hoping it's an idler pulley or something simple....

jro10 · 03-15-2021, 04:09 AM

Our noise was only evident when under load - as the RPMs got higher or when steering (never happened when out of gear). So maybe, just maybe, it will be a simple fix for you. Drove us crazy for a while trying to diagnose the problem...

kt_maxum · 04-17-2021, 09:10 PM

Well it turns out the sterndrive failed while on the water last week. The sound I was hearing must have been a gear/grinding issue. Had it pulled and it's not salvageable (both upper and lower gears are damaged, along with the housing). I'll need to replace it with a new or remanufactured unit.

Anybody have suggestions on a good dealer in remanufactured engines? With the demand for engines today it's tough to find one!

mmwjr · 04-17-2021, 09:40 PM

Quote:

Originally Posted by kt_maxum

Well it turns out the sterndrive failed while on the water last week. The sound I was hearing must have been a gear/grinding issue. Had it pulled and it's not salvageable (both upper and lower gears are damaged, along with the housing). I'll need to replace it with a new or remanufactured unit.

Anybody have suggestions on a good dealer in remanufactured engines? With the demand for engines today it's tough to find one!

Is it the engine or outdrive that failed? You first paragraph is a failed outdrive but your second paragraph is about engines, two completely different things.

kt_maxum · 04-17-2021, 09:59 PM

Sorry it's the outdrive that failed. I'm searching for a remanufactured outdrive.

Thanks,
Ken

mmwjr · 04-18-2021, 12:51 AM

Quote:

Originally Posted by kt_maxum

Sorry it's the outdrive that failed. I'm searching for a remanufactured outdrive.

Thanks,
Ken

Have you tried google? I believe Jasper sells them as well as several places that sell rebuilt engines. There’s also a company called SEI that makes a aftermarket version that some like and some have had issues with.

kt_maxum · 04-18-2021, 01:12 AM

Thanks, yes I did a general search but wasn't coming up with too many options. I didn't see SEI so will check them out. Thanks again.

kt_maxum · 05-24-2021, 11:35 PM

Hi all,

I wanted to pick up this thread again as it's fair to say I'm stumped. I continue to get a loud squeal from from the engine (generally front left side but tough to pinpoint). It only happens when in gear and under load (between 2,000 - 3,000 RPM - doesn't happen outside that range). Never happens when revving to that range in neutral. It's a single engine, 496 MAG.

I'm assuming it's a pulley bearing issue of some sort, but before I start going down too many rabbit holes thought I'd sum up what's been done to see if there's any suggestions. I've completed a lot of work over the last few months, some of which I thought would also solve this issue, but none has. Work included:

- Entire sterndrive just replaced, including the gimbal bearing. Alternator was making some noise at idle so I replaced it.
- Belt looks brand new (no cracks or wear). Have tried at various tensions with no change in sound. Tried a bit of WD 40 with no change. Will change it out the belt this week regardless to see if that helps.
- No glazed spots on pulleys
- No movement in the pulleys front to back
- Sound doesn't change when I steer side to side or trim the sterndrive

It looks like there might be some slight misalignment of the belt on the crankshaft pulley, but it's hard to tell. Any thoughts would be great.

Thanks for the help!

jparsons121 · 05-25-2021, 01:00 AM

Since it’s coming from the lower portside (left) I’d suspect the idler pulley. These are known to squeal when going bad. It’s could also be what’s affecting the crank, as it’s Just before the crankshaft pulley (std rotation engine).

https://www.manualslib.com/manual/11....html?page=108

kt_maxum · 05-25-2021, 01:37 AM

Thanks very much, that's a great thought.

My belt runs a little differently than the manual link (see photo attached), so I thought perhaps it was the pulley just left of the alternator. In my case I think that's the tensioner pulley? (just based on the fact that it has the adjustment screw on it). The labels on the manual link are different in that the manual labels that as one of the idler pulleys.

I suppose the other option is the idler pulley (labelledl in manual as tensioner pulley - confusing....) just left of the crankshaft pulley, which as you suggest might be causing the slight wobble of the crank?

mmwjr · 05-25-2021, 01:52 AM

Could also be the raw water pump bearing.

geoffm70 · 06-26-2024, 08:53 PM

did this ever get resolved? I have the same issue, ran the engine quickly without the belt, and same noise. coming from back of engine. sounds like a constant belt squeal.

mmwjr · 06-26-2024, 09:20 PM

Does it change pitch when you turn the wheel side to side? If so most likely it’s the gimbal bearing.