Possible Transmission Oil Leak at Shift Lever – Kanzaki KM2P

[testingthewaters91]

Hello all,

I’m following up separately from my earlier thread about the flooded engine compartment. Thankfully, we traced that issue to the burp valve overflowing—particularly when operating in reverse. For now, easing the throttle seems to have resolved it, and the engine compartment remains dry.

With the space finally free of water and the engine running more regularly, I’ve discovered what appears to be a transmission oil leak. It seems to be weeping from the shift assembly lever area on my Kanzaki KM2P transmission, which is paired with a Yanmar 2GM20F. I’ll attach a photo for clarity.

I’m wondering:

Is there meant to be a telltale or weep hole at that location?

Is it likely that a gasket or O-ring within the shift assembly has begun to fail?


A fellow sailor suggested it might simply be a matter of tightening things up, since the transmission was rebuilt about three years ago and sat idle until quite recently. Perhaps bringing it back into service has unsettled some of those seals or fittings.

I did mention this in my earlier thread, but that post focused mainly on the water ingress. I thought it best to start a new discussion devoted to this possible oil leak.

Has anyone here encountered a similar leak from the shift lever area on the KM2P? I’d be grateful for any wisdom, experiences, or guidance from the community.

Fair winds and following seas,
TTW91

 

[Don S/V ILLusion]

Unless you find someone here knowledgeable about the fittings, I’m sure the service manual for the 2GM engine would have a blow-up of parts and torque specs

 

[testingthewaters91]

I’ve been looking through the manual and diagrams, and it appears there should be some kind of bolt or screw where this hole is located. That’s why I’m reaching out—to see if anyone has encountered this before and knows whether the hole is supposed to be there by design, or if I’m actually missing a fastener.

If it’s not meant to be open, should I be plugging it somehow—or sourcing the correct bolt to go back in? I’d love to avoid causing any damage by simply sealing it if it’s meant as a vent or weep hole.

Has anyone had this same issue on a KM2P? Any details would be hugely appreciated.

Thanks again for all the help!

 

[Ralph Johnstone]

​

Any chance to get a couple of razor sharp, high def. photos of your lever arm to be sure of exactly what we're dealing with here. ?

I know I've got exploded views of this area. I'll do a deep dive later.

 

[Ralph Johnstone]

Ah Crap,

Seems that Yanmar did not include xmissions in their earlier parts catalogues. I was only able to find a KM2C xmission in their 2018 catalogue.

............... and the remote control levers do not look similar.

 

[Ralph Johnstone]

Just to further complicate matters, here's and exploded view from the 2002 Yanmar service manual but there is nothing to identify this from either a KM2P or a KM2C :

Pretty hard to diagnose what's missing without being there or some better quality close ups of your installation.

 

[Ralph Johnstone]

Just a note here but the parts catalogue exploded diag. labelled as a KM2C is quite different form the unlabelled diag. from the service manual, so the diag. from the service manul MUST BE a KM2P.

That information along with $1.25 should be able to get you a cup of coffee in any cheap restaurant. Get some high res photos and you've solved 99% of the problem solved .

 

[dlochner]

The alignment of the cam, labeled "shifter" in Ralph's diagram is critical. If it is misaligned the transmission may not go in gear or may only partially engage the clutch, which will lead to worn clutch cones. The bolt looks like it might have something to do with the alignment.

What does the transmission fluid look like? Is there too much fluid?

For Yanmar transmissions, Rick Neary at East Coast Marine Transmissions is the guy to go to. He's in NJ.

 

[testingthewaters91]

Hey everyone,

I went back to the boat today and took some high-resolution photos, as requested. They’re very detailed and should show the issue clearly.

The transmission is a Kanzaki KM2P that was installed 2 summers ago, using SAE 30 oil. It shifts smoothly and runs well underway, but it’s leaking transmission oil.

I’m not sharing my own thoughts yet—I’d rather hear your opinions without bias. It’s always helpful to get different perspectives on the same problem.

I’ve attached the zoomed-in photos below. Let me know what you think!

Thanks!

 

[testingthewaters91]

Just to further complicate matters, here's and exploded view from the 2002 Yanmar service manual but there is nothing to identify this from either a KM2P or a KM2C :

View attachment 232884

Pretty hard to diagnose what's missing without being there or some better quality close ups of your installation.

Attached is what I found.

 

[Ralph Johnstone]

Had to ask before I run, "What happened to the two bolts ?"

They're shown (just the one) in the Service Manual exploded view (the KM2P drawing) "

......................... but not in your photos.

You've also got to wonder if the oil seal is doing its job or maybe it's missing as well.

 

[testingthewaters91]

I'm going to chalk it up to this—boatyards in Colonial Beach, VA do terrible work. Ridiculous. I'm going to go ahead and try putting in the bolts, I feel as though the oil seal must be present due to the lack of weeping around the shift lever.

Also, I’m wondering about this bolt. The length and size aren’t specified, and the diagram shows the threads starting deeper inside the part, whereas in my photos, the threads begin right at the opening of the hole.

 

[Ralph Johnstone]

I told you not to get the economy transmission repair kit ................. it's cheaper because half the pieces are missing .

You're on the right course. Do you have the shims and what purpose do they serve ?

Also, I’m wondering about this bolt. The length and size aren’t specified, and the diagram shows the threads starting deeper inside the part, whereas in my photos, the threads begin right at the opening of the hole.

Consider the length carefully as it screws into the shift lever. That's probably the reason for the shims. I can't offer any ideas as to how tight or loose the bolt screws into the shift lever but it's a function of the shims.

Maybe take one last look into Youtube for Yanmar KM2P repairs and see if any information is available. The info available in the Yanmar literature is not complete. I know whay you mean by the need for a full length of thread.

 

[testingthewaters91]

Good afternoon, gentlemen and ladies.

I went to Lowe’s and picked up some M8 hex bolts with washers to replace missing bolts on my marine transmission. I’ve attached a photo showing the three bolt holes where the bolts are missing.

Here’s what I’m seeing:

The center hole is too large for the M8 bolts. An M8 bolt slides right in without catching the threads at all. I’m wondering if that hole requires an M10 bolt, or possibly a North American (imperial) size bolt instead of metric.

The two side holes also didn’t accept the M8 bolts. The threads simply wouldn’t catch, no matter how carefully I tried to start them. I was able to easily thread them onto other parts of the engine within seconds.


So at this point, it’s a bit of a mystery. I’m considering going back to the store and picking up a few different bolt sizes (e.g. M10, or imperial sizes) to test for fit.

My questions:

Has anyone else run into this issue with bolt sizing on a Yanmar (or Kanzaki) transmission or shift assembly?

Is it possible that these holes are imperial rather than metric?

Are there known variations in bolt sizes for certain models or production years?


Any recommendations or insights would be much appreciated before I make another hardware store run.

Thanks in advance!

 

[dlochner]

The center hole is too large for the M8 bolts. An M8 bolt slides right in without catching the threads at all. I’m wondering if that hole requires an M10 bolt, or possibly a North American (imperial) size bolt instead of metric.

The center hole looks like the threads have been stripped.

The two side holes also didn’t accept the M8 bolts. The threads simply wouldn’t catch, no matter how carefully I tried to start them. I was able to easily thread them onto other parts of the engine within seconds.

Get an M8 tap and gently retap the threads. It may be the threads are bunged up and just need to be cleaned. Or the bolts that were there were sheared off and the hole is plugged with the broken shaft.

 

[testingthewaters91]

The center hole looks like the threads have been stripped.




Get an M8 tap and gently retap the threads. It may be the threads are bunged up and just need to be cleaned. Or the bolts that were there were sheared off and the hole is plugged with the broken shaft.

Thanks for the feedback so far. After reading your comments, I went back and checked the alignment. The threads themselves actually look pretty good in the transmission, but I realized the shift assembly is out of alignment with the threads. So I’m thinking I might be able to carefully force it back into position, and then the M8 bolt might thread properly.

As for the center bolt, there’s a big difference in diameter between the M8 bolt and the hole, so I’m considering trying an M10 or 3/8″ bolt gently by hand, just in case a previous mechanic in the U.S. drilled it out to imperial size. If that doesn’t work, I’ll go with a Helicoil next.

Appreciate any insights or experiences with this kind of situation!

 

[dlochner]

Thanks for the feedback so far. After reading your comments, I went back and checked the alignment. The threads themselves actually look pretty good in the transmission, but I realized the shift assembly is out of alignment with the threads. So I’m thinking I might be able to carefully force it back into position, and then the M8 bolt might thread properly.

As for the center bolt, there’s a big difference in diameter between the M8 bolt and the hole, so I’m considering trying an M10 or 3/8″ bolt gently by hand, just in case a previous mechanic in the U.S. drilled it out to imperial size. If that doesn’t work, I’ll go with a Helicoil next.

Appreciate any insights or experiences with this kind of situation!

Before you start drilling out the center hole, I think it would be important to understand the bolt's purpose and why it is located off center. The lever is clamped on to the shaft, so the bolt likely has little to nothing to do with keeping the handle from slipping.

From the diagram in @Ralph Johnstone's post #6, it looks like the bolt has something to do with the spring which tensions the shifter or locating the shifter. It may serve as a tensioning bolt or some kind of adjusting bolt, since there are shims involved.

It would also seem important to understand why the bolts are missing. Were they never installed after the last rebuild? Did they vibrate out? It is obvious the mount has moved, how has that affected the alignment of the shifter? How long has it been that way? Is there any resulting damage to the transmission innards as a result?

If this were my boat, the transmission would come out and it would go off to East Coast Transmissions for inspection and rebuild if necessary. At a minimum I'd give a transmission expert who knows these transmissions a call to answer some of the questions before doing anything else.

 

[Ralph Johnstone]

At a minimum I'd give a transmission expert who knows these transmissions a call to answer some of the questions before doing anything else.

I find I must agree with Dave on this as I believe he is much older than I and perhaps more experienced . I would say that his statement about seeking expert help is your only hope at this point. I have never allowed anyone to work on my boat to date but If I wanted to do this xmission repair on my own, the only way I could get through it would be to take the assembly apart and have it laid out on the bench in front of me so I could understand the function of each and every part. And that would be with all original parts in place. It doesn't look like you've got that luxuty available to you.

Maybe search out a Yanmar dealer around you. My guy offers his expertise as free advertising for the Yanmar parts I buy from him.

 

[testingthewaters91]

Before you start drilling out the center hole, I think it would be important to understand the bolt's purpose and why it is located off center. The lever is clamped on to the shaft, so the bolt likely has little to nothing to do with keeping the handle from slipping.

From the diagram in @Ralph Johnstone's post #6, it looks like the bolt has something to do with the spring which tensions the shifter or locating the shifter. It may serve as a tensioning bolt or some kind of adjusting bolt, since there are shims involved.

It would also seem important to understand why the bolts are missing. Were they never installed after the last rebuild? Did they vibrate out? It is obvious the mount has moved, how has that affected the alignment of the shifter? How long has it been that way? Is there any resulting damage to the transmission innards as a result?

If this were my boat, the transmission would come out and it would go off to East Coast Transmissions for inspection and rebuild if necessary. At a minimum I'd give a transmission expert who knows these transmissions a call to answer some of the questions before doing anything else.

Ideally I'd be happy to pay someone to assess and fix it, but I'm on the Potomac and have yet to find anyone I trust. Do you have any recommendations?

I have to disagree that the alignment has 'obviously' shifted. The bolt holes may not line up perfectly but the outside edges of the shirt assembly are flush. You're right about the center bolt and the importance of understanding it's purpose. I guess I figured someone with a bit of experience might be here on this forum.

 

[dlochner]

Do you have any recommendations?

Rick Neary, East Coast Marine Transmissions. He was the head mechanic for Mack-Boring the East Coast Yanmar distributor until M-B got out of the service business.

East Coast Marine Transmission

East Coast Marine Transmission - Yanmar Kansaki Marine Transmission Specialists

www.eastcoastmarinetransmission.com