Volvo Penta SX with a serious rattle, please help!

Hi,

I recently decided to repower my boat as the old motor had a lot of hours and had developed what I thought was a bearing knock. The boat is an 18' 1998 Four Winns Horizon with a 4.3L Volvo Penta. Anyway, now that it's all done, the noise is still there, only worse!

It sounded as if the noise was coming from the rear of the engine, just before the drive. So I ran it without the outdrive, but the noise is still there (The outdrive also got overhauled anyway). I also ran it without all the accessories (power steering, alternator, etc.) and the noise still remains. About the only thing I haven't replaced for new is the coupler, flywheel and harmonic balancer. I should also mention that as the revs increase, the noise goes away, at around 2800rpm.

Does anyone have any ideas what it might be? Would it be ok to run it as it is for a couple of days? I'm currently away on holidays and without it there's not a lot for the family and I to do! Thanks for any help, I really appreciate it!

Re: Volvo Penta SX with a serious rattle, please help!

With the engine not running and the drive off, see if you can move the coupler and flywheel. Remove the starter and check the flywheel too.

Re: Volvo Penta SX with a serious rattle, please help!

Thank you Don, I'll give that a go today. I used Loctite on the flywheel studs and nuts so I'm really hoping that's not the problem, but stranger things have happened! Failing that, what else do you think it could be? Is there anything else I should check while I'm at it? I only ask because, being from Australia, by the time I report back on the flywheel and coupler, most people will be sleeping.

Re: Volvo Penta SX with a serious rattle, please help!

Might check that cover that goes on the bottom of the flywheel cover housing. I'm pretty sure it's plastic, but if it is steel, they do rattle if not tight.



If the drive is off, and the flywheel and coupler are tight, cover is tight and not the problem, and you still get a noise from the back of the engine, then it's time to pull the engine and see what's banging around in the flywheel cover housing.

Re: Volvo Penta SX with a serious rattle, please help!

Well, I removed the starter and the drive. Turns out the flywheel is loose, so it's engine out time again. Thanks a bundle Don, as always you're an invaluable source of information.

While I had the drive off, it reminded me to ask another question. How does the bearing carrier on the leg, with the crescent cut outs in it that allow access to the bolts, seal to the u-joint bellows? Should there be another seal somewhere? Where the drive joins the pivot housing is just metal on metal, it doesn't seem like it would keep water out very well. I can't see a seal anywhere on schematics, can I seal it with gasket maker or something?

Thanks again.

Re: Volvo Penta SX with a serious rattle, please help!

It seals against the bellows. That's why you should put some grease on the nose of the drive. It allows it to slide against the bellows easier when installing the drive. Those bellows should be replaced every 5 years as preventive maintenance.