Hi all, I'm new to this forum. Just wondering if anyone has experience with a raw water cooled Yanmar 2GM20. I'm looking at buying a yacht which has a 15 year old 2GM (raw) with 1200 hours on it. It's making me nervous about buying the yacht ($20K) knowing that a new motor in the near future could potentially double the price of the boat. Raw salt salt water and cast iron seems like a bad mix.
Any experiences greatly appreciated.

Hi Jimmy

I have a 1984 built yacht with a raw water cooled 2GM (15 hp) which is a earlier version of a 2GM20

I am not sure how many hours on it as it does not have a hour meter fitted but i assume it has a few

Before i bought the boat a couple of years ago it had a cylinder head replaced due to corrosion but the bottom end is still original as far as i know

The engine has 2 anodes fitted in the cooling system to help prevent corrosion and these need to be checked on a regular basis and replaced when necessary

From what i have found on the internet a common problem with these engines is the water injection tube in the exhaust elbow cracks where it is fitted in the elbow and this allows sea water to leak back into the cylinder head corroding the head and so i assume this is what happened to mine

When mine starts (normally starts after cranking for a couple of seconds) it is a bit smokey initially for a few seconds but then runs cleanly and smoothly

It doesn't have glow plugs fitted so i think this would be normal for this engine

Regards Don

Thanks for that, good to know