J/30 Class Association Forums J/30 Forum The Boat, Sails and Equipment New Yanmar 2YM15 vs fix or rebuild 2gm

I've had two differnet mechanics tell me that my 2GM has very low compression and needs to be replaced. It is raw water cooled and both mechanics are relectant to advise fixing it because it might be rusted internally. I would like to just fix what might be "broken" but I also don't want to be short sighted and have to fix parts of the engine every year. Can anyone offer advice? Does the 2ym15 fit easily in the 2GM space? Are there other drawbacks? Costs? Is there a realiable used 2gm for sale out there?
Any advice from someone with experience in this area would be helpful. Thanks.

Doug,

I rebuilt my 2GM raw water cooled engine. I was not burning oil so did not replace rings or bearings. The water passages were plugged. This was a winter project done in my basement and cost about $400. If you have any mechanical ability, or have friends that do, it is much cheaper to rebuild. Look at the link in my signature for Rhapsody projects and download the presentation on engine rebuild.

Low compression could be valve wear. You could do a valve job. All parts are readily available from authorized Yanmar suppliers. The Yanmar Service Manual is available on our class website, although I bought the manual from the dealer. It is very good.

Bottom line - if you do change it out, the 2YM should fit in the space. I don't know if the KM2A transmission bolts up, but suspect it does. Check with the Yanmar dealer.