certinaly anything in the MKII is ok. If you get a westerbeke, many were changed to a 3" exhaust
. You can check that. Not all the engines had issues. Still, a compressin test is not a bad investment on an old diesel. The remedy, should you not have a problem on the boat you are considering, is to pull a 3" exhaust
. Please understand that I was not tech editor during that so all of my information is second hand. However, I can tell you that none of the Yanmars have that issue.