beta engine drive plate failure

[solent clown]

last week I removed the engine and gearbox from a yacht that lost drive suddenly, Beta engine, PRM box. The selector felt ok, so I took the gearbox off on the saloon floor to discover the drive plate bolts had all sheared, and the plate holes were very elongated.
Removel of the flywheel was next, then up to the workshop to remove the remaining sheared bolts from the flywheel. No matter how I tried - and I have all the gear, I could not get one out.
At this point I split the flywheel (they are a two part unit)
The bolts then came out easily. Upon inspection of the main flywheel is was apparent that the bolts had bottomed out and bitten in to the flywheel face so the drive plate would never have been at its correct torque and able to move slightly. Eventually of course it ate the bolts , the owner had reported an increasing clunk over time putting it into drive, so that fits with the wear pattern
New plate ordered, and new bolts. The engine was only fitted 4 years ago.
The owner isnt a day sailor, he is off to spain and beyond in two weeks so one might say it was a timely failure.
The thread about washers reminded me that had they been fitted to provide clearance this would not have occurred.

 

[RichardS]

It should, presumably, have been obvious to whoever put that together that the clearances were insufficient and that some modding needed to be done, washers or whatever.

Some people should not be allowed anywhere near tools. :ambivalence:

Richard

 

[solent clown]

It should, presumably, have been obvious to whoever put that together that the clearances were insufficient and that some modding needed to be done, washers or whatever.

Some people should not be allowed anywhere near tools. :ambivalence:

Richard

It was a large company with a good rep. I am leaving that conversation to the owner.

 

[solent clown]

By way of a picture speaking a thousand words, see the marks on flywheel face at divider points


IMG_20180709_104925[1] by mark punksteel, on Flickr

IMG_20180709_104932[1] by mark punksteel, on Flickr