Yanmar 3GM30F Flexplate

[Capt.Don]

Hi everyone,
Thinking the flex plate on our Yanmar 3GM30F is starting to fail. Engine in forward at low idle there’s a clunking sound for three or four seconds, where eventually engages; or, we increase the RPMs. Sometimes transmission engages fine, without the clunk noise. Seems to run a bit rough however, it may be my imagination.

Are there any tests that I can do short of removing the bell housing and inspecting the flex plate? Any other sounds or things to look for? What is involved in replacing the flexplate; is this simply removing the housing removing the flex plate and seal and replacing with new? Any idea how many hours this might take? Any other parts I need to order?

Or is this something else altogether!


Thanks
Don

[jimbunyard]

Sounds more like a cable adjustment issue to me. You could try disconnecting the cable at the gear and shifting by hand.

[billknny]

The flex (or damper) plate on most engines is easy to change-once you get the transmission off, there it is... unbolt it and insert the new one. In most cases there is no seal involved. Be sure to torque the bolts and use threadlock according to the engine shop manual.

But... if there is a delay before the transmission engages, that's likely not the damper plate. If it's not the cable throw (as mentioned above) it might be the transmission clutch. If you do end up needing to change the transmission, change the damper plate too!

[Capt.Don]

The more I think about it, it may just be the throttle cable adjustment. Will check that next. Thanks for the suggestions,
Don

[Capt.Don]

I took a look at the shifter cable and transmission lever -- all looks fine. The only thing I noticed is the shifter lock-not was loose. I tightened; might reduce play. I'm now thinking this might be related to low RPMs and weak motor mounts. Lots of vibration, which settles out with higher RPMs.

[AA3JY]

Simplistic things first..replace the transmission fluid..