Yanmar 2GM20C Starter Motor

[NSA_Hunter]

How did this story end?
I have the same exact problem on my 2GM20F. Broke 2 starters within 2 years. I just hauled the boat out to replace the teeth ring on the flywheel and fish out the pieces of the starter resting in the bottom of the housing. Both aftermarket starters suffered broken nose castings.
The automatic reaction is to buy a good hitachi for $400+ but is that fixing the symptom or the problem?
Engine would crank. Don't notice anything odd. I will check timing

[four winds]

Breaking the nose off aftermarket starters..........

It finally happened to me shortly after having the starter off for oil line replacement. Had been fine for over three years.

Compare the after marking casting to the factory starter casting, and you will notice the mounting flange ears are substantially thicker than the factory starter. I think it is because the strength of the aluminum alloy is less than the factory alloy. So they beefed it up, all good. But, on the nose cone there is no clearance available to beef up the nose cone. There is a lot of force on that cone from where the bushing supports the bendix.

If things aren't perfect alignment it causes issues with the weaker casting in that area.

There is no shimming or adjustment on the starter mounting. So it seems a small misalignment matters. But no way of knowing if its right. Carefully tightening the two bolts gradually and back and forth between them is the best you can do. Plus don't over tighten, probably squishes the cheap metal a bit causing bad alignment. Doesn't take much.

You will have no problems with the factory starter.

There is a Bosch equivalent at around 180 dollars US. But I can't find one in stock anywhere. It's out of production I think, but rebuilds have been available. Appears to have a much better nose casting. Probably a good starter.

[NSA_Hunter]

I am going to order the Hitachi. Meantime the damage is done and instead of sailing, I'm sweating down below pulling my trans back to get to the flywheel.
One would think alignment, but there's nowhere for misalignment to occur, The starter bolts to the block casting that houses the flywheel bolted to the crankshaft flange. You can't shim the starter away from the flywheel like a car. Shimming only moves it perpendicular to the wheel, not along the same plane away from it. .

[four winds]

Glad this thread popped back up.

Found the Masco starter this time.


Starter for YANMAR 1GM, 1GM10, 20GM, 2GM, 2GM20, 2GMF, 30GM, 3GM

[NSA_Hunter]

I ran across that Masco starter once before in my searches. I wonder if that design is really an upgrade. Beside added complexity with the gear reduction, it has no support in front.
I'm glad you posted this. I think I'll call them and talk to their tech people.

[Teknishn]

Glad this post popped back up as I am looking to replace my 1GM starter next month. Would like to hear how that Masco replacement works out for you. Good Luck!

[NSA_Hunter]

Well I talked to Masco. They answered all my questions well. I went ahead and ordered one.

[four winds]

The reason the Masco doesn't need nose support is because the bendix shaft is well supported at both ends independently of the armature bearings. When it extends out it's not cantilevered as far from the support as the standard setup.

[NSA_Hunter]

Pulled my transmission and removed the flywheel yesterday. It was much easier than I expected. The flywheel teeth are pretty chewed up, but I still can't tell if it was the cause or the results of 2 broken starters. I hope the diesel shop I take it to today can install the new ring and maybe tell me what could cause it. Meanwhile the new Masco starter is waiting to go in. It will take longer as I have to properly torque everything.

[Acushla]

The supplier of the Chinese aftermarket starter refunded the purchase price of the failed starter and offered no replacement.
This was then replaced from the US market with and after market starter with no end bearing support but with a heavier shaft. There have been no issues with this starter since
ACUSHLA

[NSA_Hunter]

I told the retailer of the aftermarket starter that i didn't want a replacement. They didn't offer a refund. Sounds like you have the same Masco starter now that I installed. I hope it is the last. Flywheel ring gear and starter are new now.