Yanmar in '79 37c

[monocerosin]

So examining my motor for identification the only numbers I found were "2T-3" where I expected it to say 2qm20. According to the service manual everything is as expected other than that number. Could this be a different head on the original motor? My hull number is 52m79f if that matters.

 

[Hollyberry]

Is it really only a 2 cylinder engine on a 37 footer??

 

[monocerosin]

Is it really only a 2 cylinder engine on a 37 footer??

There are 2 injectors and most of the motor matches the diagrams for the 2qm20 in the 1979 Hunter 37c. The 3qm30's come in the late 80's I believe.

 

[monocerosin]

 

[monocerosin]

 

[monocerosin]

Sorry for the poor images, they are from video. I have ordered many maintenance parts, oil, atf, gaskets, seals, filters, etc. In anticipation of turning it over just to see if it can run and then basically rebuild it. I just want to make sure that marking means something that differs from the 2qm20.

 

[monocerosin]

There are 2 injectors and most of the motor matches the diagrams for the 2qm20 in the 1979 Hunter 37c. The 3qm30's come in the late 80's I believe.

I mean 1980 not late 80's

 

[rardiH36]

Same engine as in my 1980 Cherubini Hunter 36. Many years ago I made several posts about my maintenance experiences. Hunter made modifications to the 2QM20. It is not totally stock. Tomorrow I will dig into this forum's archives and post the links which may be helpful.

 

[rardiH36]

Good Morning monocerosin:

I had only modest success finding some of my years' past posts. Not as easy as I expected. The links to a couple that should be of help getting oriented are below. Namely where to find the engine's nameplate. And a description with my hand drawn diagrams of the cooling system modifications that Hunter made to the QM series engines. This is really important do know. Because the mods are not referenced anywhere in the Yanmar manuals. (You cited "service manual in your opening post, so presume you have it?) I observed in the photo of of the front of your engine, blue residue around the cover of the engine's coolant pump. Contained in my link below is that the QM engines were intended to be seawater cooled. That is seawater pumped through the engine block. Hunter (presumably with Yanmar's assistance) modified so that anti-freeze would cool the engine. An external heat exchanger and an belt driven seawater pump were "plumbed" into the system. I see that your heat exchanger is mounted on the port bulk head to the left of the engine. By it's profile, it looks like the original "Sen-dure". If so and it has not been replaced over the years, good chance that the tubes inside are leaking (mine were when I bought my boat in 2007) which will allow the seawater to infiltrate into the anti-freeze circuit. If this has occurred, possibly seawater has been circulating through the engine block. Which would account for the blue residue. Anti-freeze I doubt would cause this. Anyway something to look at.

As you get into your engine, post info on your progress! Feel free to ask for further information. I am not a mechanic, but have learned lot over the years about the special issues particular to the modified 2QM20 engine.

3QM Engine Plate Location?
2QM20 questions from H36 '80-82 new owner -

 

[rardiH36]

Re my post above, I should have written "starboard" bulkhead.

 

[monocerosin]

Wow, this incredibly helpful. I was definitely scratching my head at some of the things you mention. Will look at everything again with new eyes. Thank you for the resource, and I will continue posting my progress.