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dreuge 08-15-2012 03:19 PM

Yanmar 2QM15 Rebuild

In early July, I came to my boat after being away for three week and found the engine seized. It was locked up solidly, in that it would not budge even a little bit after soaking the cylinders with Marvel Mystery oil for several days. It turned out to be a blown head gasket which let salt water into a cylinder.

I hauled the engine out with the boom and rebuilt it for a cost of only parts and machine shop work. The engine is back in and is working great. I have posted photos online if anyone is interested.

Yanmar 2QM15 Rebuild - a set on Flickr ( )

Unless you live near a Yanmar distributer, knowing which part numbers to order can be time consuming and costly. I include my list below in order that it may help someone down the road.

My total cost was about $825.

Machine shop work

Cylinder head work $300
Honing piston rod bushings to fit piston pins $40

Price quote from Mastry Engine Center


head gasket (124060-01331) [$28.79]
valve cover gasket, o-ring type bonnet (124060-11311) [$8.47]
oil pan sump gasket (124060-01743) [$16.26]
exhaust manifold output gasket (124701-11911) [$9.15]
exhaust manifold Adj. gasket (124770-13131) [$1.87]
exhaust flange gasket (124770-13171) [$27.43]
engine zinc cover gasket (124450-11681) [$1.53]
thermostat gasket (104211-49160) [$1.36]
exhaust manifold forward flange gasket (124770-13181) [$9.00]

Engine parts
piston rod bearings (124060-23300) [2@$13.38]
piston w/ rings (724060-22722) [2@$86.37]
piston pin bush (124060-23910) [2@$5.08]
cylinder liner (724070-01900) [1@$111.77]

Other Parts
zinc (27210-200300) [2@$3.60]
zinc packing (23414-250000) [2@$0.85]
thermostat (124770-49200) [1@ 27.10]

Misc. item
Lubriplate #105 assemble lube
(coating piston, rings, piston pins, bearings) ~$7
Copper Cote gasket spray
(for head gasket and copper exhaust gaskets) ~$5
Permatex form-a-gasket #2
(gasket dressing for other gaskets and hoses) ~$4

RichH 08-15-2012 03:27 PM

Re: Yanmar 2QM15 Rebuild
Ya did good!!! The QM series can easily make it to 10,000 engine hours, even if rebuilt.

Bradhamlet 08-15-2012 03:39 PM

Re: Yanmar 2QM15 Rebuild
Nice going my 3GM rebuild was $3,000. However there was more than just a cracked head, there was much welding to do. Any way Yanmars are great, fuel sipping powerful moters.
Lancer 36

Beersmith 08-15-2012 03:40 PM

Re: Yanmar 2QM15 Rebuild
nice! I am doing the exact same thing with my 4JH2E.

Documenting the whole process in my blog (see signature for link)

Beersmith 08-15-2012 03:41 PM

Re: Yanmar 2QM15 Rebuild
for those who are looking for parts manuals (service manuals have been posted here many times), join; they have the parts manuals for download.

dreuge 08-15-2012 04:02 PM

Re: Yanmar 2QM15 Rebuild

Originally Posted by Beersmith (Post 909959)
for those who are looking for parts manuals (service manuals have been posted here many times), join; they have the parts manuals for download.

Yes, I did look there, but I could not find a parts manual for the 2QM15.

dreuge 08-15-2012 04:45 PM

Re: Yanmar 2QM15 Rebuild
I want to add another point regarding Yanmar exhaust mixing elbows.

The 2QM15 service manual lists the part numbers for the two mixing elbow options(see pages 11-10 & 11-11) . Part number 124070-13500 is for the downward angled elbow. The U-type mixing elbow option is part number 124070-13520.

The Yanmar list price for the part number 124070-13520 is $186.26. There is an option for a cheaper (both price and part quality) yanmar mixing elbow. Yanmar part number 128270-13600 which lists for $147.16.

I was reluctant to go with the cheaper mixing elbow because I was told the cheaper one last only a year before needing to be replaced, and in the long run one can save $$ getting the better unit.

I search around and found that HGE manufactures the the better U-type mixing elbow. The part number is HGE3520. One can buy it online for about $70!

See "" or " ".

I purchased one from MMISeattle (great folks), and it came with a 3 year warranty!

Banjo boy 01-13-2013 01:00 PM

Re: Yanmar 2QM15 Rebuild
Great job! I'm doing a similar job on my 2qm15 and am using your parts list! Thanks! I am needing sending units for the water and the oil. Do you happen to have the part #'s for those items?

Again, great job. I hope I can do the same.

dreuge 01-15-2013 07:09 AM

Re: Yanmar 2QM15 Rebuild
Sorry, I don't know these numbers. My guess is that they are standard. The only concern would be to see us the temperature sends differ for raw water cooling versus a fresh water system.

casey1999 01-15-2013 02:48 PM

Re: Yanmar 2QM15 Rebuild
Thanks for great post. I have a similar set up with a 30 year old Yanmar 3GMD and will be looking at having to do the same in the not to distant furture I am sure.

Did you notice any changes in exhaust or operation before the engine siezed up?

I get some white exhaust (steam?) when I run my direct sea water cooled engine and am wondering if it is sea water entering the cylinder through a bad head gasket. Thinking maybe somtime soon I should pull the engine and spilt the head and block, clean all the cooling passages, replace head gasket.

Also, I have been flushing with fresh water after use, maybe buy a little more time out of her.


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