Yanmar 2QM20 - Should I rebuild or replace it? Maybe convert to electric?

[a64pilot]

Many, many years ago I drove both a 71 bug and a 71 VW Westfalia.
There was a book written by a Lockheed engineer I believe and in that book he made the assertion that no one made enough money to pay someone else to work on their VW.
I say that is even more true for a small Marine Diesel.

Overhaul it your self, you’ll be surprised at how simple that is, and while you may be able to reuse the cylinders and Pistons, in a wet sleeve engine I’d replace them and start with a new engine.

You only retire a wet sleeve engine when parts become unavailable.

[Compass790]

Originally Posted by a64pilot

Many, many years ago I drove both a 71 bug and a 71 VW Westfalia.
There was a book written by a Lockheed engineer I believe and in that book he made the assertion that no one made enough money to pay someone else to work on their VW.
I say that is even more true for a small Marine Diesel.

Overhaul it your self, you’ll be surprised at how simple that is, and while you may be able to reuse the cylinders and Pistons, in a wet sleeve engine I’d replace them and start with a new engine.

You only retire a wet sleeve engine when parts become unavailable.

Yes, agree with what A64 pilot wrote, IF you can afford the Yanmar prices replace

[a64pilot]

I bet I can overhaul that motor for much less than a replacement or an electric conversion, and add to the value of the boat.
It can’t be that expensive, 2 grand at most?
I know it’s been a few years, but I used to figure my cost on an aircraft engine overhaul at a grand a hole, and that was new pistons, cylinders that include the head and valves etc.
That was 20 or so years ago, but a little 2 cyl Diesel can’t be much, there just aren’t that many parts.

[Wotname]

Originally Posted by a64pilot

I bet I can overhaul that motor for much less than a replacement or an electric conversion, and add to the value of the boat.
It can’t be that expensive, 2 grand at most?
I know it’s been a few years, but I used to figure my cost on an aircraft engine overhaul at a grand a hole, and that was new pistons, cylinders that include the head and valves etc.
That was 20 or so years ago, but a little 2 cyl Diesel can’t be much, there just aren’t that many parts.

Never underestimate what Yanmar can charge

Single cylinder YSE 8 - one main bearing ~$60, the other main bearing ~$500. OK the expensive one is a bit bigger and includes a thrust face but.....


EDIT: However what a64 said is mainly true.

[CFS Klopas]

Just had my Yanmar 2GM overhauled for 3k + the 2k the yard ran through figuring out it needed a rebuild. I was quoted 5k for a used replacement and 7k for new.

[Pizzazz]

Last year my 2GMF slipped a bearing and I ended up replacing it with a 2GM20F for $2,800 off craigslist. Perfectly happy so far, I guess I just got lucky. At the time, a 2YM15 (newer but only 12hp was quoted at $6400).

If you decide to rebuild you can have my old 2GMF for pretty much free. The shaft was polished by a machine shop and it is possible to put together but I do not have the time or inclination to do so.

Good luck.

[Compass790]

Originally Posted by Pizzazz

Last year my 2GMF slipped a bearing and I ended up replacing it with a 2GM20F for $2,800 off craigslist. Perfectly happy so far, I guess I just got lucky. At the time, a 2YM15 (newer but only 12hp was quoted at $6400).

If you decide to rebuild you can have my old 2GMF for pretty much free. The shaft was polished by a machine shop and it is possible to put together but I do not have the time or inclination to do so.

Good luck.

Wish i wasn't 5000 miles away, would love to have a go at rebuilding yr 2GM if Leveche didnt want it. Be nice to escape from the din & vibration of our YSM8. Good motor otherwise.
My advice to Leveche is get the 2GM if poss as mostly common bits AFAIK

[Cheechako]

I'll just throw in here that the GM series have had their problems with pistons, even on low hour engines. To my thinking the QM was a better engine. Not saying they are necessarily "bad" engines, but I have personal knowledge of 4 with piston issues.

[leveche420]

Thank you all for your advise!!! I decided to rebuild the engine myself with the helps of a fiend of mine. We have the disassembled it and have all parts on the bench. We are trying to find all the parts that need to be replaced. We are replacing sleeves, pistons, valves and pretty much everything. We are planning to send injectors, injection pump and engine head to specialized shops. I will post pictures and status updates soon!!

[leveche420]

Originally Posted by Pizzazz

Last year my 2GMF slipped a bearing and I ended up replacing it with a 2GM20F for $2,800 off craigslist. Perfectly happy so far, I guess I just got lucky. At the time, a 2YM15 (newer but only 12hp was quoted at $6400).

If you decide to rebuild you can have my old 2GMF for pretty much free. The shaft was polished by a machine shop and it is possible to put together but I do not have the time or inclination to do so.

Good luck.

Thanks Pizzazz!!! Where are you located? your old 2GMF will be useful for parts!

[Wotname]

Originally Posted by leveche420

Thank you all for your advise!!! I decided to rebuild the engine myself with the helps of a fiend of mine. We have the disassembled it and have all parts on the bench. We are trying to find all the parts that need to be replaced. We are replacing sleeves, pistons, valves and pretty much everything. We are planning to send injectors, injection pump and engine head to specialized shops. I will post pictures and status updates soon!!

Timely update, thanks.

Coincidently I'm picking up a 2QM20 today as a possible overhaul project.

[sailah]

I just had my cylinder head recut on my Westerbeke. Was $90 to cut head and I had them magnaflux it too ($180). He didn't think I needed it but this was my second time replacing head gasket so I wanted to be sure.

He was kind enough to Dykem the head and show me the low spots when he skim cut it. Basically anything blue was a low spot. I think he said he took 0.005" total. Was def blowing by in a couple spots and pushing coolant out.

If you are looking for a machine shop and are shipping it out anyways, I can highly recommend them. They have good equipment and are old school machinists.

Engine Rebuilding-Automotive Machine Shop-MA,NH,RI,CT,VT,ME

[leveche420]

Thank you all for your help! You will be able to follow the progress here:

https://doctorsailboat.com/2019/01/2...-yanmar-2qm20/

[sfnz]

Originally Posted by leveche420

Thank you all for your advise!!! I decided to rebuild the engine myself with the helps of a fiend of mine. We have the disassembled it and have all parts on the bench. We are trying to find all the parts that need to be replaced. We are replacing sleeves, pistons, valves and pretty much everything. We are planning to send injectors, injection pump and engine head to specialized shops. I will post pictures and status updates soon!!

did you have the usual WTF moment when you whipped the head off and found a one piston up and one down configuration same as you'd expect from a 2 stroke ?

[RaymondR]

Originally Posted by leveche420

Thank you all for your advise!!! I decided to rebuild the engine myself with the helps of a fiend of mine. We have the disassembled it and have all parts on the bench. We are trying to find all the parts that need to be replaced. We are replacing sleeves, pistons, valves and pretty much everything. We are planning to send injectors, injection pump and engine head to specialized shops. I will post pictures and status updates soon!!

Good luck with your rebuild.

It's a nice feeling to look at a new engine in your boat but the gratification you will get from a successful rebuild with your own hands will far outweigh it and repeat for many years.