Yanmar 1gm-Lumpy

[olly_love]

We have a yanmar 1gm (about 10 years old) in our boat with the standard gearbox and shaft,
it sounds very thumpy when on tick over almost a cracking noise from the compression, does anyone have any thoughts what it could be? or are they all like this

 

[Bosun Higgs]

If there is a problem ( impossible to decide from a description) the first places to look are:

1/ anything touching - for example exhaust hose banging against hull or engine sump banging against bearers

2/ engine mounts failed - the ones on the yanmar are very soft anf the rubber does seperate from the steel of the mount.

 

[Tranona]

Yes, they bounce around at tickover. Try speeding up the tickover a bit but not too much as you don't want a jerk when you go into gear. Check the engine mounts, first that the lock nuts have not vibrated loose or the rubber has failed or become detached from the mounting.

 

[Burnham Bob]

mine did bounce a lot on tickover until it was warm. the 'crack' was the ignition stroke which was always had a very explosive sound until warmed up. check for anything loose as suggested but if its always been like that its like mine was!

 

[alan17]

Single cylinder diesel. Bound to be lumpy on idle. If everything is tight and not moving to hit anything. Check mountings if all OK. Leave well alone. If it ain't broke don't fix it!