Yanmar 2GM20 question

[ErikL]

My 1960 Pearson Triton has a Yanmar 2GM20 and I am trying to figure out when it was built. I know the boat originally had a gas engine so the Yanmar is a re-power. Any help would be appreciated!

Yanmar 2GM20
Engine serial #01063
HP rating: 16
RPM: 3400

[skipperpete]

This might help but no serial numbers to pin it to a more precise date

[ErikL]

Thanks Pete, I saw that chart (Toad Marine?) but none of the info matches up. It's really weird but I haven't been able to find anything online that makes sense. All the 2GM20's say 18HP but mine is clearly labeled 16HP. And no engine/serial numbers that start with "0".

[Greatest Lakes]

Is it a 2 gm20f? Some were made in Japan and some were not. If it follows with the F it was. Mine is also labeled 16hp and the engine number begins with 0.

[GordMay]

AFAIK, There’s no easy way to cross reference Yanmar engines, to build date.

The “GM” series ran from 1980 to 2005.
The “2GM20F” was an 18HP [maximum HP @ 3600 rpm, bored out 2GMF] indirect Fresh-Water Cooled engine, c/w 55A alternator, built from 1983 ‘till 2005.

[hberg]

The 2gm2p0f has a continuous rating of 16hp/3400rpm but a max output of 18hp/3600rpm. I'm not sure of a standard choice exists but in the manual for your engine, the name plate dictates the continuous rating.

I have had luck emailing Yanmar directly and sending photos. They were very helpful about my odd 2qm engine (8hp) and I'm sure with an engine number could give you all the build info! https://www.yanmar.com/marine/contact-us/

Last thought is: what kind of alternator do you have? I won't know the years any switches were made but perhaps someone else will. (I have a KM3P on my 2gm20f, I think the original, but the manual I found online shows KM2A.)

[hberg]

Transmission not alternator...

[skipperpete]

Originally Posted by ErikL

Thanks Pete, I saw that chart (Toad Marine?) but none of the info matches up. It's really weird but I haven't been able to find anything online that makes sense. All the 2GM20's say 18HP but mine is clearly labeled 16HP. And no engine/serial numbers that start with "0".

The 16 hp on the label is continuous duty at 3600 rpm while the 18hp in the specs is power @maximum fuel @3600, the only time you might see 18hp is towing, full throttle against the dock lines or powering into a 40 knot headwind.