Yanmar Saildrive and Engine mounts

[maverick2911]

Hi there,

our port engine starts to shake when I use it with more than 1500 rpms. Since the last change of the engine mounts has been about 1000 hours ago I think it is time to replace them.

I have replaced engine mounts many times on my older boats. But I never had a saildrive before. Can anyone tell me the procedure or has by any chance the workshop manual? I have the manual for the Engine, but not for the saildrive.

Its a Yanmar 3GM30F with a SD20.

Thanks in advance! :-)

John

[DotDun]

Have you checked the prop? Or the prop shaft? Something is bent.


The SD20 Service Manual was just uploaded to the 'manuals' section of CF. It's in moderator queue, assume it'll be ready to download soon.

http://www.cruisersforum.com/forums/...?do=file&id=22

[maverick2911]

I have checked prop and shaft. Everything looks normal.

Thans for the manual!*It is great to have the manual in case we run into trouble with the Saildrive. I did not find anything about replacing the mount though …

[DotDun]

Does it shake in neutral?

[maverick2911]

No, it does not shake much in neutral. I just checked and revved it up to 2000. No shaking in neutral. But when we last motored a couple of days ago there was clearing a vibration that we did not have before. But only under load and when we are motoring with more than 1700 rpms. Can it still be the mounts? They are pretty old …

I replaced the seals on the shaft last November when the boat was out of the water. Everything looked good. How can the shaft be bent? We did not catch any fishing nets or anything else …*

Thanks for your help!

John

[DotDun]

Trade the propeller with the other side and see if the problem follows the prop.

[maverick2911]

The boat is in the ICW right now. And I cant see my own hand while diving ;-) But yes, that would bring an answer.

[gamayun]

Have someone dive the boat and see if the prop moves at all. It shouldn't. It might have something to do with that new shaft seal. Not sure if the same applies to a sail drive but the haulout seems to be the one variable that has changed. Did it start right after the haulout? The mounts you can do a visual on or have someone knowledgeable do that. A thousand hours doesn't seem that much!

[Bean Counter]

The engine mounts may be ok, what about the flexible mount under the sail drive. Clearance between bolt head and the high side of the lower bracket 1mm.
See also page of service manual 2-8 for a picture of it.

[AussieCat]

We had a similar issue recently. Turned out to be a thin piece of twine caught between prop & casing. There was nothing flapping around so was almost impossible to see. Several high rev runs in reverse eventually cleared it.
Easy to check mounts. Just a metal bar or large screw driver to lift enough to check if cracked. If broken you should be able to change with out disturbing the sail drive. If it turns out to be an issue with sail drive (unlikely) you'll most likely need to haul out to fix.

[DotDun]

I would be real careful changing the mount on the rear of the SD. You don't want to let the weight sit on the diaphragm. The diaphragm is heavy duty, but you are holding the rear of the engine also. Block it up/chain it up first.

[Fore and Aft]

I have surveyed a couple of yachts that have had loose nuts holding the propeller onto the sail drive shaft. One guy had let his go so long that when he went to tighten the nut the shaft snapped off!