Is a 2QM15 a worthy upgrade from a YSM12

[Hermit Scott]

I am looking at a 2QM15 tomorrow, $600. The guy says it runs fine but doesn't know how many hours are on it. A major rebuild kit is $430. (1)Does any one know what a major rebuild kit entails?
(2)Is this engine better for getting parts for it than the YSM12, pricewise, availability?
(3)Is this a worthy upgrade to the ysm, or should I hold out for a 20 to 30 hp engine?
(4)How much smoother/quiter is it?
(5)Is the construction of this engine more like a modern diesel? For instance does it have an oil pan, how is the fuel injector design compared to newer yanmar models?
Thank you for your help.

 

[Ed Schenck]

The 2QM/3QM series has not been built since 1979 or 1980. Parts are still available, I got mine from Torresen Marine. Check Q&A on their website. Their site will explain the parts in a rebuild kit I think. The QMs were solid and very heavy. My new 3YM30 is almost 300 pounds lighter than the 2QM20 that it replaced. The QMs were raw-water cooled with after market heat exchangers. Does this one have the heat exchanger? Then it must have two water pumps, one for the internal circulation and usually a belt-driven pump from the thru-hull into the heat exchanger.

 

[BobM]

It will be a lot smoother than a 1 cylinder, but don't expect miracles shake-wise. My 2QM15 runs fine and I haven't had any trouble getting parts for it from Torresen. A 2 cylinder will definitely help resale vs. a 1 cylinder. It is still pretty fuel stingy too. Horsepower-wise it isn't really much of an upgrade. Mine will push my boat to 5.5 knots cruising...still shy of hull speed...plus your boat has 2000lbs on mine.

 

[zeehag]

i think hull speed is best gained with the wind. engines are good for getting out of storms and into and out of tiny places....if there is a budget like mine--that of broken shoestring--i would go for the least expensive over all solution.....i am not certwain what tha tis at this point--do you know how many hours are on each engine?/ do you know the history of the potential replacement?/ will it guarantee you happiness and freedom?? donot forget to take into account the prop and shaft--will the ones you have already be adequate or will they be different from what the larger engine needs?>? what about the tranny?? do they both take same one??. i learned that something that looks like it might be tha answer might just take more money to effect than just repairing the old stuff-- i also learned the opposite is also true--gotta figger the costs and expenses against each other to make sure---- goood luck!!~~~~~~_/)~~~~~~~~

 

[sailaway78]

Do you really want

Hermit,
Do you really want to spend that much money, to gain 3 hp, from an engine of unknown quality. Seems to me liike you have already spent the bucks rebuilding the 12, and all you need is possibly the oil pump redo. I would first off, not be too concerned with the oil pressure. Did you know that when autos first came out with idiot lights instead of guages, that they were triggered at 6psi. Have you checked the pressure regulator valve. Guess thats what they call it. There is a little spring loaded valve that controls the oil pressure. Also, what weight oil are you using. Basically, I guess what I'm saying is you have a known quantity in what you have. So, for 600 bucks you are considering another engine, plus 400 bucks for a rebuild kit. Plus the unknown labor and modifications of installing it. More than likely at the very least the motor mounts and prop. The very good possibility you will have to shorten or completely change out the prop shaft. What if the shaft size is different. New coupler?? The shaft will almost certainly need to be shortened, unless you have a lot of space between the prop and the rudder. And you are in the long run going to gain three horespower. With all that being said, I had a 2QM15 in my old S2, and it was a fantastic engine. Totally bulletproff, and trouble free. Biggest problem I had with it ever was a bad thermostat.

 

[Ted]

Also consider the engine mount configuration. Will you have to do modifications to your engine bed?

 

[Hermit Scott]

Ed this one is raw water cooled no aftermarket exachanger. That is a big negative.
Zeehag-the ysm12 was almost completely rebuilt. New valves, piston/liner bearings and gaskets. The oil pump can't really be rebuilt completely because the shaft is supported by the case. It's in the boat and running fine, except the oil pressure is below what the book says it should be. It has 15 hours on it.
The 2QM15- is of unknown hours. But running. 3hp more is a gain of 25%, I don't know if that will give me 25% more speed. 1 more knot would be worth it.
I don't think the engine stringers will have to be modified. But that isn't that big of a deal. If the oil pressure is good on this engine I won't rebuild it. Probably just do a valve job and repaint it. $100 for that.

I read a lot of posts on here and another forum where people rebuilt their ysms and they locked up shortly after. There was a post on here a few months ago where a guy had the same problem. I thought his mechanic didn't replace the main bearings and his oil clearance was too large, but now I believe it to be the oil pump shaft housing was worn and leaking oil back into the crankcase instead pushing on to the filter.

 

[zeehag]

as long as the 2qm is in decent shape and you are prepared for the switch--it might make sense to do the changeover---i donot know if i would wait for the lock up then do it or if i would just go for it--but then, i just changed out a bad 4-107 for a goood 4-108--in my formosa--then found a big hole, so was good i did!!! just might be the thing to do for you as well....dont know until ye get there--i am not familiar with the ysm's..i just know my 2qm20h is awesome...even with raw water cooling--lol--she runs waay cool as i have her in pacific and that water never warms up!!--her running temp is around 100-120.....yanmar dealer says is good...i know that when ye get the engine in and bugs worked out that you will LOVE the 2qm!!!!!..

 

[BobM]

2QM15 might actually be a 14hp motor, not a 15hp...go figure. I heartily recommend running your engine until it blows up. You have little to lose at this point, as the engine won't be worth anything. I'd talk to a good machine shop. I am sure they can tell you if they can put a bushing in the cover. If they can it can be your newest invention!

 

[zeehag]

buy the 2qm and run the piss outta yer already yours engine and then ye has a backup plan when the ysm detonates--mebbe soon, mebbe later......always good to have a backup plan!!!!!

 

[kloudie1]

Scott, I am a "fix it" guy (with machine shop experience) and would take the case and pump to a machine shop and have them bush it.. can't be more than $100 or so to get it done right.. ?? If they have a good milling machine with digital controls, they can precisely center the bush in the case, or if they are patient and good, can do it in a good drill press. Bronze is probably OK for this application and since the bush would be new, you can get them to make it a standard size so that it can be easily replaced in the future if need be.. With the engine recently rebuilt, and a refitted pump.. I'd think this would be a great bet on reliability instead of an unknown engine.

 

[Ron20324]

And get a spare bushing.

 

[Hermit Scott]

If they can it can be your newest invention!

I actually read about doing that in archives somewhere.
I don't want to screw with this engine anymore if I don't have to. If 20 to 30 psi is good enough then I will be happy with that. I would feel differently about it if this was a 20 horse power engine, which is what I think I need to get up to hull speed.
I am reluctantly going to let the 2gm15 pass. It is almost what I want. If it was 20 hp, or fresh water cooled, I would probably get it.

 

[jerryf609]

I think that is a wise choice, Scott. I have the 5411 in my 1983 Catalina 30 and 11 horsepower is barely ok, but when I upgrade it will be to something in the 20hp range.

I've looked at BetaMarine 3 cylander 20hp, it is new diesel technology, lighter, fuel stingy not as stinky etc.

If anyone is considering a repower, you might check out these people. I have no affiliation with them.

http://www.soundmarinediesel.com/index.html

 

[kloudie1]

Scott, Seems like some used stuff would be available from last summer's storms, that ya could clean up/rebuild for repowering?

Looking at the Yanmar engine manual on this site: http://www.ship468.org/boats/Catalina30/YSM12/index.htm
They list the low oil pressure warning trigger set to 1.5 PSI !!!
Two things come to mind.. one is that may be why some have broken after a rebuild.. and two that you have plenty oil pressure

 

[jibes138]

Catalina 30 power

My neighbor had a 1980's catalina 30 and it had the same engine as my O'Day 35 a Unversal M25. This is a 21 HP motor, three cylinder. I think the displacement of the Cat 30 is close to my 35 which is 11,500 pounds or so. The Cat 30 is a beamy boat for the length and I've sailed on several. seems like 11HP is really underpowered.

 

[Hermit Scott]

I turns out this engine wasn't a 2QM15. It is a 2QM20! And no one bought it so the guy came back and offered it to me at a reduced price. The only problem is, he has the manual to the 2QM15 not the 2QM20. So I will need to pick one of those up before I start tearing it apart.
I am glad everyone on here gave the 2QM20 the vote of confidence. I am picking it up Monday.

 

[Cpt. Jon]

Very cool Scott!

 

[Hermit Scott]

I bought the engine. It is definitely a 2QM20 not a 2QM15. So it is roughly the hp of the universal that many have in their C30's.
I have a few posts out there trying to figure out if this motor will fit in my boat with out too much modification. No one that knows has responded. My only real concern is the weight. The seller says the book says it is 300 lbs. but this is not the engine he thought it was.
Does anyone have any specs on the 2QM20?
More importantly has anyone had a C30 with a 2QM20 installed? If you have what prop did you use?

 

[Roger Long]

Does anyone have any specs on the 2QM20?

I have a 1979 s2QM20, the manual, and tremendous affection for the engine, one of the best small marine diesels ever built. However, yours doesn't look like one. It's a similar Yanmar or maybe an earlier version.

Send me some pictures of the other sides and ends so I can compare it better with mine.