Need YSM12 Yanmar Engine and/or Parts

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jsgoev

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Sep 14, 2012
5
Hunter 30 Mobile Al
Hi All,

I am working on a Yanmar YSM12 in my 78 Hunter 30. There was very low compression and investigation showed leaking valves and a worn piston cylinder/rings. My hope is to find a working YSM12 in working condition or one that will need less time and parts required to rebuild. Please contact me at jsgoev@kc.rr.com or 913 671 9456 if you have anything available. Thanks.
 
Oct 30, 2011
542
klidescope 30t norfolk
was it smoking bad when you gave up on it check wet compression by pouring heavy oil into cilinders and recheck compression #'s if it comes up it just needs a valve job
 
Jun 10, 2004
135
Hunter 30_74-83 Shelburne
Hey how are you or your mechanic measuring compression? With the injector out? Does your gage fit and stay right in the injector hole on the YSE? I might try measuring my compression this winter, I have a low output issue, but me and most everyone I talk to kinda think if the motor starts at all it has plenty of compression. Haven't done it (compression check or pop test) because my injector is stuck in the head and I'd have to destroy it to pull it out. I have a new injector but I am interested in what kind of set up you used/ made up to seal the compression gage to the cyl head/injector port.

Getting the engine out and a new one in requires fairly substantial lifting equipment above your companionway and a bit of work disconnecting and reconnecting mounts, shaft, exhaust and cables. That's all time consuming old stuff waiting to mess with you and not necessary if you rebuild in place. I might try just the valves and guides before I did the ring/liner job. Is it not starting at all? I'd also be certain I had a nice full sump of new lube oil (I like Rotella T Syn). That being said, if I ever pulled my one lunger 12 there would be at least a two cylinder 20 replacing it.

I get my parts from Torrensen Marine in Muskegon Michigan, they are much more responsive than my local marina for Yanmar parts. They won't ship to all states because of Yanmar's territory rules but that may have changed.
 

jsgoev

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Sep 14, 2012
5
Hunter 30 Mobile Al
I am not sure how the mechanic was measuring compression, but he said it was turning over much too fast and easy. He first put on a new fuel injector pump which was clearly worn out. The head is off and he will have a repair estimate tomorrow.
 
Jun 10, 2004
135
Hunter 30_74-83 Shelburne
I am not sure how the mechanic was measuring compression, but he said it was turning over much too fast and easy. He first put on a new fuel injector pump which was clearly worn out. The head is off and he will have a repair estimate tomorrow.
OK- he'll probably will want to double check the compression release stem isn't in the released position before he starts digging deeper. Its a small rod sticking out the side of the head with a cable linkage attached to a little lever screwed to the bulkhead. It's there to lift a valve off it's seat when someone wants to try to hand start your motor. And it sounds like the piston/ rings and cylinder liner are still assembled, so no one has laid eyes on the rings, and getting an accurate I.D measurement to compare wear to allowable wear is difficult. My book says the I.D nominal is 85 and "max allowable wear or scratch" is .35, I'm guessing the units are millimeters. I'd just take a light and a mirror and look for obvious wear. Mine's going on 33 years and I've abused the hell out it at times I'm embarassed to say, but still fires on the second crank when the fuel gets in there and the lube oil is circulating properly with the sump full. I definitely have heard that no compression whir a number of times, once after a repair when I hadn't filled the sump, and once when I let the oild sump run low.
 
May 6, 2012
303
Hunter 28.5 Jordan, ON
was it smoking bad when you gave up on it check wet compression by pouring heavy oil into cilinders and recheck compression #'s if it comes up it just needs a valve job
Isn't it more likely to need piston rings as opposed to a valve job if the numbers come up after doing a wet check?
 
Oct 30, 2011
542
klidescope 30t norfolk
yea Nom De Guerre your right way to catch that still waiting to hear if the old yanmar runs or not
 
Aug 24, 2011
20
2 -Hunters 30 Stockton MO
On my friends computer on the way to the boat. The mechanic has the valves ordered and plans to have the engine back together to test next week. Sorry I do not have more answers, but I will get a first hand look soon.
 

jsgoev

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Sep 14, 2012
5
Hunter 30 Mobile Al
Good news as the engine is running. Reworking the valves solved the low compression problem.
 
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