yanmar 3gm30

[zeehond]

<span style="color:blue"> </span> I have a problem with my yanmar 3gm30 raw water cooled diesel . The symptoms are:- difficult to start, once started won't take any load till warmed up, Crankcase is pressurised, when warmed up it seemes to run ok but uses a lot of oil (3litres from falmouth to portsmouth)and we sailed most of the way but not a great deal of smoke evident. When engine is stopped some smoke comes out of the air inlet filter. Anyone any thoughts on this?. Does anyone know of a good,cheap (joke)supplier of yanmar spares if engine needs major surgery?. anyone know of alternative engine mounts for the 3gm30? has anyone got any spares for this engine.

 

[Col]

Sounds like you have a cylinder down on compression. Compression test would verify this. Then decide how far you want to go into it really. Could be badly seating / stuck valve, stuck or broken rings or head gasket fault.

 

[burgundyben]

Hello Col.

A cylinder leak down test would tell more though? If you can hear a hissing in the inlet, exhaust or crankcase you'd know exactly the problem?

I reckon R and D can supply mounts.

 

[Peterduck]

It sounds to me as though you may have any one or all of a number of problems active there. Diesels are intended for hard work, and love to be pushed hard. When they are not, they either get coked up, or the bores become glazed, or both. This reduces compression, which makes them hard to start. The cure for this is, unfortunately, complete dismantling, cleaning , and re-assembly. It is unlikely that new parts, apart from gaskets will be required. The bores would need to be honed to remove the glaze. The honing also leaves millions of fine, shallow scratches on the bores, which hold oil so that the piston and rings are lubricated during their high-speed travel.
Peter.