Bukh flywheel and vibration

[Rhylsailer99]

After changing my engine mounts my engine seems to vibrate more even on tickover. I have a feeling the flywheel is not perfectly flush, can this happen sometimes? Would it be a good idea to remove and re seat it.

 

[Rhylsailer99]

Also, I over torqued a couple of the bolts because I was unfamiliar with the torque wrench and how it works. Only afterwards I realised I should have stopped at one click.

 

[Boater Sam]

If the flywheel was OK before you changed the mounts it should be OK still. Are they the correct mounts?
Is the engine running on all cylinders?
What exactly did you undo , loosen, refit etc.?

 

[neil_s]

It may be that your new mounts are working! Bukh engines are known for their good balance, so perhaps the old mounts had just 'bottomed out'. You could just check the truth of the flywheel as you rotate it by hand with a gauge against another part of the engine.

 

[Poignard]

Also, I over torqued a couple of the bolts because I was unfamiliar with the torque wrench and how it works. Only afterwards I realised I should have stopped at one click.

If in doubt, fit new ones.

 

[Rhylsailer99]

Yes, the old mounts were really bad and had just bottomed out. The engine does not look to be moving on the mounts but seems to be more vibration than before. I have just managed to get the mounts a bit tigher so will check later when the tide come in.

 

[Graham376]

We once had problems with a club launch engine vibrating after new engine mounts fitted. Turned out the new mounts were too soft, changing for harder ones cured it.

 

[vyv_cox]

When I installed my Yanmar I had to play around with several mount hardnesses before settling on a combination that was vibration free throughout the rev range.

Is it possible that there is some debris or similar between flange and flywheel?

 

[Poignard]

Yes, the old mounts were really bad and had just bottomed out. The engine does not look to be moving on the mounts but seems to be more vibration than before. I have just managed to get the mounts a bit tigher so will check later when the tide come in.

The rubber mounts are there to minimise the transmission of vibration to the hull. Soggy mounts will mean less transmission but can cause other problems due to excessive movement of the engine.

Your new, and therefore stiffer, mounts will mean more vibration transmitted to the hull, as you have noticed.

When I bought new mounts for my BUKH DV10 the supplier accidentally sent a stiffer grade than that recommended. I didn't notice, and fitted them. To be honest, I didn't notice much difference in vibration; and left them in.

To check if the flywheel is running true, you can of course use a clock gauge but a piece of stiff wire attached to the engine at one end with the free end positioned close to the flywheel periphery will do just as well.

 

[Rhylsailer99]

The rubber mounts are there to minimise the transmission of vibration to the hull. Soggy mounts will mean less transmission but can cause other problems due to excessive movement of the engine.

Your new, and therefore stiffer, mounts will mean more vibration transmitted to the hull, as you have noticed.

When I bought new mounts for my BUKH DV10 the supplier accidentally sent a stiffer grade than that recommended. I didn't notice, and fitted them. To be honest, I didn't notice much difference in vibration; and left them in.

To check if the flywheel is running true, you can of course use a clock gauge but a piece of stiff wire attached to the engine at one end with the free end positioned close to the flywheel periphery will do just as well.

I think that is the issue because before I fitted them the engine went with a clunk when engaged and the engine moved way too much. I checked for movement when running and it looks solid now.