Noisy shaft

[Hillbilly]

Not as exciting as the title may indicate....

I have twin D6 330’s on shaft (2012). Port side is super smooth and quiet. Stb, not so much. When I engage idle and anything over,, I get what a can only describe as a slight grinding noise. I also get slight vibration above 1500 RPM. Any thoughts what this could be? I’m thinking along the lines of cutlass bearing, or knocked / out of balance prop. Stern glands are water fed, no sign of a leak.

Engine is smooth as the port side when increasing revs in neutral, and gearbox oil fresh.

Any thoughts much appreciated, cheers.

 

[Portofino]

When it’s out of the water grab the props and put a lot of side ways / lateral force on the cutless bearings .
Compare the play .There should be none .

 

[burgundyben]

Have a look at the engine mounts under load.

 

[Bandit]

Consider cutless bearing wear and engine alignment. Other possibility would be prop damage.
No idea of boat or age first thought would be cutless bearing , eiether way a hoist and inspection will show, Maz tolerance about 1.5 mm movement vertically or horizontally.

 

[oldgit]

Having just involuntarily replaced a cutlass bearing and one or two other minor items ,would suggest that may well be the problem.
You will need to lift boat to check.
Easy to do simple check without involving paid assistance.
Just grab the prob and shaft and forceably try to wiggle it in "P" bracket.
Bit of play is OK but serious ability to get it to go clonk clonk means rubber sleeve in bearing is knackered.
No need to panic, still useable to creep around but not high speed whizzing.
Need to plan.
New cutlass about £45- £75.00 depending on source.
The shaft does not have to be drawn and cutlass can be replaced DIY with care by removing prop and using a special device ( go on internet for details).
If you pay somebody they will almost certainly want to remove propshaft, undoing engine coupling is not fun.
The cutlass may have just worn over time,however the Mk 1 eyeball can give an indication if something else is amiss.
Such as this


or this ...

 

[BruceK]

Well I never! OldGit having problems with his shaft drives. How come that little gem escaped notice? Could have dined out for the day on the windfall.

 

[oldgit]

Well I never! OldGit having problems with his shaft drives. How come that little gem escaped notice? Could have dined out for the day on the windfall.

Grrr

New shaft arriving tomorrow..."P" bracket being straightened at this very moment.
... still, every cloud has silver lining pulled the stern gear to bits Saturday and skillfully managed to avoid being anywhere a TV or radio.
Presume its safe to come out now ?

 

[BruceK]

Not really, at least, not without a tin hat

 

[Neil_Y]

As a bearing supplier there are clearances on new bearings and suggested times for replacement.
As a very rough guide (as clearances depend on shaft size and bearing wall thickness)
38.10 shaft new clearance 0.09mm change when clearances approaches 1.0mm
50.80 shaft new clearance 0.13mm change when clearance approaches 1.27mm

We advise fitting our bearings as a clearance fit bedded on epoxy which allows you to have a dry run installation and see if P bracket is aligned. With shaft chocked you should be able to slide bearing into P bracket and rotate it.
We're not that well known in the bearing world but we have got Lloyds approval.

 

[Hillbilly]

Thanks all, had an engineer out with me today - couldn't quite pin point the sound, but thinks it could be coming from the gearbox rather than any stern gear. Idea is to lift the boat tomorrow to have a look around the shaft / P bracket etc, to give a better idea. There are no obvious signs of any gearbox troubles (no seal leaks), but I guess you can never tell.

IF it turns out to be the box, does anyone have any suggestions for a good re-con company? Its a 2012 ZF HS80 unit. Hearsay tells me ZF boxes are bullet-proof....but I guess there is always the exception! Fingers crossed we lift her and see a wonky prop / worn cutlass bearing!!

 

[Hillbilly]

small update - had her lifted - bearings and glands all fine. Shaft straight, prop is pitch perfect.......shaft turns freely. Looks like a rumbling in the box...or drive plate. Not the best news, but also only being used at river speeds at the minute, so probably not super urgent and can be refurbed during the winter lift out. Any recommendations on gearbox rerun companies would be appreciated, cheers.