Forums, Engine, Gearbox, Stern Gear, etc, Yanmar YM2 engine mounts

BobBraithwaite at 29/09/2014 09:17:32
Ive recently purchased Ariel a 1977 C32 which is fitted with a Yanmar YM2, 2 cyclinder, 20HP. Im interested to know what engine mounts people use. The engine does vibrate at low revs and makes a knocking noise when you turn it off, which is why i wondered whether my mounts arnt man enough. Ive taken one out and it seems to be fine in terms of condition.
(i have pics but dont seem to be able to attach)

George Isted at 30/09/2014 12:16:24
I am not familiar with the YM2 but the 2GM-20 certainly bounces around a fair amount at tick-over, mine was significantly improved this season by increasing the tick-over RPM from 750 to 800 or so. My engine has standard Yanmar mounts from what I can see.

I think that Yanmar offer two types of mounts, soft an hard, for this size of engine and depending on how your gearbox is connected to the prop shaft (hard or flexible coupling) you may need one type or another. A flexible coupling (like an Aquadrive coupling) will allow more movement/misalignment so softer mounts may be used therefore less noise transmitted to the hull.

I fitted a Centaflex gearbox coupling last winter to help with any misalignment and reduce cutlass wear but I am not sure it has helped reduce noise, I expect that is still being passed to the hull via the mounts and general engine noise is escaping the engine bay. She really needs new noise insulation in the engine bay but it’s not an easy job without removing the donker.

Probably worth asking around for a trustworthy marine engine engineer and get them to take a look.

Hope you are enjoying Ariel.