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Old 06-01-2025, 20:52   #1
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Yanmar 2QM20 Transmission Parts Search

Hello Cruisers!
First post for me here.
I have rebuild a Yanmar 2QM20 with a Kanzaki YP-7M transmission ( long lever port side ,round bell housing) photo 3
I am hoping the forum can help me with finding the following for
the YP-7M transmission:
Reverse gear ( part# 120220 83200) see photo 1
Idling gear ( part# 124770-83030) see photo 2
These parts are no longer available through any Yanmar dealer.
The YP-7M is a bulletproof unit and many have outlived the motor! ( I have a set of new friction disks!)
I would appappreciate it very much if somebody could point me towards the workshop or garden shed where these two parts (or a complete transmission) are hiding

Fair winds for 2025
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Old 10-01-2025, 04:57   #2
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Re: Yanmar 2QM20 Transmission Parts Search

Hi runningfix, I note you haven't got any traction with your first post on CF.

If you are looking for used replacement gears, it might help you give us your generalised location. CF has members all around the world but unless we know where you are, they might not be interested enough to help.

There has been a lot of 2QM20 engines removed over the years and someone somewhere must have an unwanted Kanzaki YP-7M taking up space.

What is actually wrong with the gears in your box? I can't see much damage in the photos. Depending on the detail of the damage, an engineering shop may be able to weld and re-machine the damaged section.

You also search (on line) for possible marine engineering shops who do work for fishing and small work boats in SE Asia (Thailand, Phillipines, Indonesia etc). Likewise in Cornwall and Devon in the UK. These guys could have old Yanmar engines still around. NZ work boats also had these engines.

If you really get stuck, you might be able to locate a serviceable YP-10M or a KBW10A. Both of which should bolt on to your 2QM20. I THINK a KH18 (ex a 3QM30) will also work but this would need checking.

There is good international FB group you could try - https://www.facebook.com/groups/465795967682309
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Old 10-01-2025, 06:18   #3
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Re: Yanmar 2QM20 Transmission Parts Search

Greetings, and welcome aboard the CF, runningfix.

In addition to Wotname's good advice:
E-Bay listings for Kanzaki Transmissions
https://www.ebay.com/shop/kanzaki-tr...i+transmission
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Old 10-01-2025, 21:27   #4
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Re: Yanmar 2QM20 Transmission Parts Search

Hi Wotname and GordMay,

Thank you for the welcome.

I am reaching out to this forum from Victoria,beautiful British Columbia on the west coast of Canada.My sailboat, a Camper & Nicholson 31 (#7; 1976)is in my ownership since 2019. I decided to rebuild the original Yanmar 2QM20 motor after making sure all the parts would be available…..they are,however the transmission parts are no longer available.

The reverse gear and idler gear have a run-out of 7/1000”( 0.1778 mm).As far as I am aware this can not be corrected hence my quest to find these gears.

Thank you for pointing out the other transmissions that are compatible.Some photos I have seen of these transmissions show a spline shaft connection to the flywheel whereas the YP-7M is bolted to the flywheel with 4x M10 bolts.I will research this further to get clarity as this might be a elegant solution to my problem.Most 2QM20 around me (that I have seen) have one of the other transmissions. I am wondering how common the YP-7M transmission actually is.

I have reached out on the Facebook groups but so far had only scammers responding.. (

Reaching out to the UK and Asia are my next steps …. the gears are somewhere and hopefully I will find them.I thank you for your support and I will keep you informed of my progress.

If you come across a KANZAKI YP-7M transmission………. )))))))))))

Fair Winds to all.
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Old 11-01-2025, 03:10   #5
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Re: Yanmar 2QM20 Transmission Parts Search

Quote:
Originally Posted by runningfix View Post
.........

Thank you for pointing out the other transmissions that are compatible.Some photos I have seen of these transmissions show a spline shaft connection to the flywheel whereas the YP-7M is bolted to the flywheel with 4x M10 bolts.I will research this further to get clarity as this might be a elegant solution to my problem.Most 2QM20 around me (that I have seen) have one of the other transmissions. I am wondering how common the YP-7M transmission actually is....
Ahh... yes, you are correct. Disregard what I said about the KBW10A box, it does have a splined input shaft as far as I can tell. I fairly certain the YP-10M has the same connection as your YP-7M as I have a YP-10M box in a shed and I kinda remember unbolting the M10 bolts. I don't recall the number though. When I get a chance, I'll have a look at the clutch housing / flywheel assembly and let you know. Unfortunately I can't part with this gearbox as I need it for a planned 2QM20 rebuild.
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Old 11-01-2025, 03:59   #6
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Re: Yanmar 2QM20 Transmission Parts Search

Quote:
Originally Posted by runningfix View Post
..........
The reverse gear and idler gear have a run-out of 7/1000”( 0.1778 mm).As far as I am aware this can not be corrected hence my quest to find these gears.
..........
This is interesting as I don't know anyone who has measured the runout in these vintage gearboxes. Not saying it shouldn't be done though. I couldn't find any specs for runout in my QM engine manuals (which include gearbox service information). Perhaps you have a more detailed Kanzai manual. Does it give you the service and wear limits for this runout?

Are you referring to radial runout or axial runout?

If axial runout, I am GUESSING this would due to a worn bush (idler gear) or worn bearing (reverse gear). The bush could be fabricated or it might available as an aftermarket item. The bearing should be available as an aftermarket item.

If radial runout, then yes, a new gear is required or a very expensive exercise of having the teeth rebuilt in a machine shop.

Is the 7thou the combined radial runout of the meshing of both sets of teeth or does each gear have 7thou of radial runout.

Unless you are expecting to be engaging reverse gear at high power settings for long periods (which would be unusual for the recreational sailor) and depending on the actual wear limits from the manual, I MIGHT be inclined to ignore any radial runout as there is no load on the idler and reverse gear engagement except when going astern. Don't forget the QM series were designed as tough workhorses for work boats. The average recreational sailor doesn't stress the reverse gear greatly!
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Old 11-01-2025, 04:38   #7
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Re: Yanmar 2QM20 Transmission Parts Search

Running fix using Facebook market place and just changing location you can look at Yanmar QM diesels for sale all over the world. The YP gearbox must be a rare beast. I looked at probably 10 QMs and none had that gearbox.
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Old 13-01-2025, 14:35   #8
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Re: Yanmar 2QM20 Transmission Parts Search

Hi Fore and Aft,
Thank you for your support and suggestion. At it with FB.
The 2QM20…. Not the B ,H,Y,F variants were apparently fitted with the YP–7M transmission
in the early production run, then changed to YP–10M.

The YP—10M was also coupled to the Yanmar 3QM30.

And yes you are right : rare beast indeed , also a regional thing somehow.

I will keep on hunting…. And if you see the beast holler!!

Fair Winds!
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Old 13-01-2025, 15:27   #9
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Re: Yanmar 2QM20 Transmission Parts Search

Hi Wotname!

Thank you for sharing your very relevant insights.

The run–out is axial : caused by forcing the bellhousing home with the reverse gear and idler gear not meshing…. (((.One can see the marking on the gear teeth . So , a very high point load that caused the run–out. It also damaged the friction disks for which I found new replacements in the UK.

During the rebuild I generally found very little wear which tallies with the< 2000 hour run time documented in the previous owners log.

Running the motor in neutral all is good. In reverse and forward gear a grinding noise is present.The runーout is also evident on the gear flange to which the friction disks is attached…. (. I had a dial gauge on all components to evaluate the damage.

I will just persist with my search and keep you all updated on my quest.

Fair Winds
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Old 14-01-2025, 16:40   #10
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Re: Yanmar 2QM20 Transmission Parts Search

Quote:
Originally Posted by runningfix View Post
.......
The run–out is axial : caused by forcing the bellhousing home with the reverse gear and idler gear not meshing…. (((.One can see the marking on the gear teeth . So , a very high point load that caused the run–out. It also damaged the friction disks for which I found new replacements in the UK.
........
Ouch! Maybe there is a silver lining though. The defect is a not a wear issue, rather it is a result of a 'one off' error; perhaps it can be fixed with a 'one off' repair.

Assuming it is only the gears that have been distorted and there is no damage to shafts or bearing housings, then MAYBE the gears can be made true again (or true enough). At this point, what do you have to lose by trying to straighten the bent gear(s) in a press and then machine out any remaining error.

New bearings (and bushes) MIGHT help.
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Old 22-01-2025, 18:28   #11
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Re: Yanmar 2QM20 Transmission Parts Search

Hi Whatname,
The only damage is on the gears ,all else is running true.As you are suggesting using a press to reverse the damage is something I am leaning to more and more.
Your argument is persuasive , especially in the absence of replacement gears!
Worst that could happen is the gear cracks…
The cost of having these gears machined is prohibitive.
Let’s see how this will turn out….
Just wondering how many 2QM20 where fitted with the YP-7M transmission.Not too many people have heard of them.
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