Mercrusier 3.0 noise

Just wanted an opinion on a noise my 1991 Bayliner is making. It has a Mercrusier 3.0 (sn D610831) with an Alpha one drive (snod559854).

Ther seems to be a noise comming from the engine compartment that almost sounds like a rattle (sort of like a cardboard box with rocks being shaken). My gues is that it's probably the gimble bearing. The previous owner said that the bellows were replaced last year when he bought the bought (due to leaking u joint bellows) but didn't know what all was replaced.

My question is, is this something that will slowly get worse, or fail all of a sudden. I'd like to get through at least the next month or two before replacing.

What will happen if the gimble bearing fails? What are signs that will tell me it's failing or has failed? I haven't taken the boat out for a ride yet, I will very soon. These nosies are happening at idle in the driveway (with muffs) in nuetral.

Is this a difficult fix? I've done a lot of work on my Glassport, but paid someone else to do the transom rebuild (it looked like everything was pretty corroded and hard to remove)

Thanks for any advice!

Re: Mercrusier 3.0 noise

you'll have to pinpoint the rattle yourself because none of us are in front of the boat. A mechanics stethoscope can be had for 10-15 bucks at most any sears store, that will help you nail it down. Are you sure your not hearing the exhaust shutter that sits inside the exhaust collecter (just below the rubber boot that comes off the exhaust riser). The shutters to rattle, and that is normal. See if the noise is coming from there.

ps~~ gimball bearings usually don't "rattle". They typically growl and howl.

Re: Mercrusier 3.0 noise

Pull the outdrive off and start it. See if the noise goes away.
If the noise is still there, the drive and gimbal bearing are NOT your problem.

Re: Mercrusier 3.0 noise

Could be a loose flywheel, not uncommon as you think. I've also heard rattling noises coming from loose bolts that connect the engine to the outdrive. Like others have said, you got to narrow it down.

Re: Mercrusier 3.0 noise

The U-Joints can make a noise when they go bad. If it had a leaky bellows and they were not replaced at that time, maybe they are your problem.

When you pull the drive as Don recommended, look at the U-joints. If all rusty then they are suspect. If you start the motor with the drive off and there is no noise, that makes them even more suspect.

Download the service manuals for your engine/drive from the Adults Only sticky.