Vibration in Volvo Penta Saildrive

[bgrimwade]

We are currently cruising in west Malaysia and during the last anchoring we tangled with some 1.5inch warp which stalled the engine. with this now cleared and no other fouling of the propeller a vibration has developed in the sail drive if the engine is run in gear at over 1500rpm and increases in amount the higher the revs. Local mechanics have given a number of reasons many of which I have discounted including dirty injectors, dirty fuel etc!
As it only occurs in gear and never in neutral I am concerned some damage has been done to the sail drive unit. I believe there are two possibilities - gear box problem or the drive shaft cogs at the bottom of the leg may have been damaged due to stalling.
I would be grateful if someone could advise how to resolve which - I lean towards the latter problem but I have little experience of saildrives I will be taking the boat out of the water in Lankawi in about 2 weeks and could investigate more thoroughly then - but how?
Any suggestions gratefully received
Bgrimwade

[Steve_C]

I would first try at looking at the prop, that is the most likely source.

[DotDun]

I agree, most likely a bent prop.

If any, the most likely damage to the saildrive would be the clutch and the symptoms would be not staying in gear.

Good Luck!

[cdennyb]

If it were anything internal like a bent shaft the gears would most likely be very noisy as well. Take a dive with a mask and look it over real close, you might find a small piece missing which would indicate an out of balance condition like mentioned above.

[Ex-Calif]

1.5 inch warp is big. Stopping the engine is significant.

I would also look very closely at the engine mounts, the saildrive mounts, the boot on the saildrive as well as seconding (thirding?) a good look at the prop.

Bending any of the shafts on a saildrive would be pretty significant and would likely result in oil leaking out or (just as bad or worse) water leaking into the saildrive.

For this reason I would also look at the saildrive oil. Milky oil is bad news. To allay your fears about gear damage, any damage might also reveal in metal particles (flakes & slivers) in the saildrive oil as well.

I am assuming from your post that you have run the engine to a fairly high RPM out of gear and there is no engine vibration when out of gear at all RPM levels?

[butxeta]

I also would say it's the prop. A friend of mine had the same problem, and did not solve it untill they changed the prop.

[bgrimwade]

I am told the prop is undamaged but will check when it comes out of the water in two weeks - currently unable to dive and the water is far from clean! a 3 knot current does not help either!.
The sail drive oil is fine - not milky or discoloured and there are no leaks from the flange 'Will need to change the oil during lift out to check for metal particles in the oil as pumping does not get all the oil out.
The engine runs smoothly to 3000revs out of gear.
I will post a further response and let you know what is happening
Many thanks

[Ex-Calif]

Sounds good so far.

In checking the prop make sure you also check the tracking. Basically use a ruler or staight edge against a fixed part of the boat and one blade tip. Then slowly rotate the prop while holding the straight edge still and see if each blade tracks to the same point.

[markpj23]

I too suspect prop damage. Does the vibration also happen in reverse gear or only when going forward? And what type of props - fixed / folding / feathering?

[barnakiel]

Start with making sure the prop is real clean, not bent and there are no pieces of whatever it was stuck in between the saildrive parts.

Otherwise, they say if one gets vibration that increases with revs, it is due to centrifugal forces, so either something is not balanced, or something is bent.

But start by making absolutely sure the set-up is free from any obstacles, dirt or whatever.

If you lift or dry the boat then you can visualy check the system, also for bends. If your tidal range is ok, then just careen her and go for it.

b.

[bgrimwade]

Thanks for the response - they are all very helpful. The prop is a three blade folding prop and the vibration does not seem evident in reverse but I will need to check it again1
Regards
Bgrimwade

[bgrimwade]

Update on saildrive- on lifting the boat we checked the prop but no measurable damage.
We then disassembled it and found some tight balls of the rope that had entangled with the prop behind the folding prop and adjacent to the shaft. Nothing else was apparently wrong. Also checked the drive t see what was in the i but it was all clear- we shuld be able t d a check at sea in the next few days
Brian

[colemj]

If it still has the problem, it is the rubber damper installed between the saildrive and the engine. This is designed to dampen/smooth the forces during shifting and can tear if the prop is stopped suddenly. The damper is considered a part of the engine in the parts schematics, so look for it there and not the saildrive schematics.

Mark

[bgrimwade]

Mark
Many thanks for the advice - currently no problems with it now.
Regards
Brian

[Laidback]

Not often one can say "been there done that!"
Passing Rebak island on our way to Bass Harbour - Langkawi, picked up a length of 3'' hawser - that stopped the 125 Hp engine on our Mariner 52 motor-sailer.
Took some time to get it off !