Looking for a Yanmar YSM8 or 12

Bud22569 · Jul 22, 2011

My boat has a YSM-12 (the engine is not for sale). I think that engine was only built for about 3 years in the late 1970's. The YSM engines appear to be strong yet simple engines but when the engine is running you think you are riding on the African Queen. I assume you are refitting where a YSM engine had been mounted in the past. Good luck finding one. I rebuilt mine a couple of years ago and was successful in finding all of the parts I needed (including a new head).

Mine has the YSM oil pump problem. It appears that there is too much clearance around the oil pump in the engine case which causes the oil pump to have trouble taking suction on startup after sitting for a few weeks. I have developed a method to prime the oil pump to work around this problem.

Hermit Scott · Jul 22, 2011

Bud H said:
My boat has a YSM-12 (the engine is not for sale). I think that engine was only built for about 3 years in the late 1970's. The YSM engines appear to be strong yet simple engines but when the engine is running you think you are riding on the African Queen. I assume you are refitting where a YSM engine had been mounted in the past. Good luck finding one. I rebuilt mine a couple of years ago and was successful in finding all of the parts I needed (including a new head).

Mine has the YSM oil pump problem. It appears that there is too much clearance around the oil pump in the engine case which causes the oil pump to have trouble taking suction on startup after sitting for a few weeks. I have developed a method to prime the oil pump to work around this problem.

One guy fixed that problem by taking the front cover to a machine shop and having them mill out the housing and have a bronze bushing pressed in and then hone out the bronze bushing to be very accurately matched to the pump shaft. I rebuilt my engine a few years ago and I have the same issue. I am going to do this eventually. I am going to replace the engine in my boat but not yet.
These engines are pretty loud and only 12hp. My 11,000 lb. boat needs a little more get up and go.

Bud22569 · Jul 22, 2011

Hermit, post the details if you ever have a fix done to the oil pump clearance issue. I explored putting a Beta Marine engine in my boat. They have a 14 hp one that hey claim is a fairly easy repower for a YSM12. I'll probably run the old YSM12 until it just won't run and can't be repaired anymore. It is not far from my slip until I can be sailing. So I usually don't go through 10 gallons of diesel per year.

Hermit Scott · Jul 26, 2011

Art,
I will sell you mine as soon as I get this 2QM20 I bought in Kemah installed in my boat. I am not doing a total rebuild on this motor just cleaning it out and redoing the head.
I did a fairly comprehensive rebuild on the YSM12. New main bearings, cylinder sleeves, pistons and rings. The crank was ground to match the new bearings. The head is completely redone with new valves, guides the whole thing. Water pump rebuild as well. It has only had synthetic oil in it from day one. This was all done in the end of 2008. I have receipts, pictures and there are many posts on here about that rebuild.
It starts so easy and runs flawlessly. It is only 12 hp and undersized for my 11,000 lb boat. I knew that when I built it though. But it was all I had at the time.
Anyway I have been sitting on this old 2QM for a while but am now motivated to get it going. If I don't sell this YSM I am going to buy an old junk 17' cuddy cabin boat and make this an inboard for it to put around the ICW.
Normally I would have just private messaged you because this is more like a want ad than a post that is helpful to all but it appears you are new and may not check on that feature , so email me at maxrepmail@yahoo.com if you are interested.

Looking for a Yanmar YSM8 or 12

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