Yanmar 2QM & 3QM Starter Motor Compatibility?

[Wotname]

Does anyone know if a 3QM starter motor is physically compatible with a 2QM engine?

Electrically they are different with the 3QM more powerful and the 3QM has different internal electrical aspects but I can't find any difference in the service manual regarding the physical aspects.

The reason for the question is that I need a 2QM starer motor and may have found a 3QM one for a reasonable price but I can't check physically that it will mount and work on the 2QM.

The service manual calls up Hitachi S114-206 for the 2QM and a Hitachi S12-47 for the 3QM and google gives me a very confusing array of starter motors for a variety of Yanmar marine and industrial engines so any help is appreciated!

[jimbunyard]

According to Amazon (and others), this one (the S12-47) does.

https://www.amazon.com/STARTER-YANMA.../dp/B01AIVTQCS



Several sources show the 2QM15 starter as having a 11 tooth drive gear whilst the S12-47 shown above has a 15 tooth and the S114-206 has 8 and a nose cone. None of this necessarily means that the two are physically incompatible.

To be sure a call or visit to a local starter shop might help clarify...

[Wotname]

Originally Posted by jimbunyard

According to Amazon (and others), this one (the S12-47) does.

https://www.amazon.com/STARTER-YANMA.../dp/B01AIVTQCS



Several sources show the 2QM15 starter as having a 11 tooth drive gear whilst the S12-47 shown above has a 15 tooth. This does not necessarily mean that the two are incompatible.

To be sure a call or visit to a local starter shop might help clarify...

Opps, I should of mentioned I have a 2QM20 and not a 2QM15 - sorry.
I think (but don't know) the 2QM20 has 15 teeth.

[Lepke]

Fewer teeth give the starter an easier time of turning the engine. Usually you will see the same starter with the number of gear teeth varying depending on the number of cylinders or compression ratio. Many companies now have their starters made by specialty manufacturers, mostly in China. You will find many starters spec'ed as replacement for several engines.

[Captain Bill]

I had a starter go due to a leaking mixing elbow dumping salt water on it. I got the Hitachi part number and went to an automotive electric shop. The Yanmar starter was over $600. He said he could get me a new Hitachi for about $300, an american built after market for about $130 or a chinese built aftermarket for about $80. He did not recommend the chinese unit. I got the american one and 4 years later it's still going fine. Surely you have such shops down under.

[charliehows]

I got a new starter motor from AAE Wholesalers in SA for my 2qm20. I dont know about 3qm30 compatibility but i recall finding somewhere the important specs - direction of turn, number of gear teeth - my old mtr had the cowl, new one doesnt (better/newer bearing technology)

[Wotname]

Update:

OK, received the used 3QM starter motor and mounted it to the 2QM.
It sort of fits.

It fits well enough to be useful but some small modification are required.
It is slightly too long in the body and fouls with the block drain tap; I will rework the drain tap. The starter flange is too wide for the 2QM studs and I will replace them with longer studs.

The upside is is the starter is more powerful than the original 2QM starter .

I suspect the aftermarket Chinese starters will fit both engines.

The pictures tell the story better.