Yanmar KM2A un-serviceable? Also need transmission basics too.

[bonkle]

This is what mechanic #1 said. I'm trying to get ahold of mechanic #2. An un-serviceable transmission seems highly unlikely, especially for the 80s. he said there's also a chance that the engine (2GMF) and trans came as a package and a re-power may be in order (he's waiting for a call back from Yanmar).

Symptoms:
Put it in forward, clunk clunk clunk like the prop shaft is missing a bearing. Floor it and it pops into gear and seems normal. Boat sat for a month and now it cannot rev in forward (like the prop is 3' diameter). reverse seems fine... it's never been good at going backwards, but it's smooth.

My understanding:
The clutch is causing the issue. Somehow, the clutch acts as the front bearing on the prop shaft. There's a "cone" somewhere, but every pic I've found, the clutch looks like a regular ole automotive clutch... or is that just the flywheel? I've also read about the shift lever on the case being sensitive? Fluid level, color, consistency is good.

Questions:
1: Can a competent mechanic with no boat experience (me) remove the tranny without sinking the boat?
2: Where do I find info or parts for this old tranny? All I've read is to contact mfg or service shop.
3: Would it be better to invest in a re-power? My 2GMF starts and runs like a dream and could bring in a grand to help offset the re-power? I'd rather pay $2k and have a supported drivetrain than $1k and still have an engine with no support.

 

[Tally Ho]

Should be no reason you cannot unbolt the transmission from the engine and replace it with a rebuilt transmission (or have your transmission repaired.

I have a Yanmar 2GM20 F engine (1988) and the Kanzaki KM2P transmission.

Can you pull the transmission? I would think so, if you have some tools and basic mechanical skills.

Lots of info and videos on YouRube to help you know what to look for…

This guy did a series…removing the trans, disassembly, and reassembly. He did the work on the transmission himself.

The first video will give you some good info on how to remove it…

Greg

 

[bonkle]

Should be no reason you cannot unbolt the transmission from the engine and replace it with a rebuilt transmission (or have your transmission repaired.

I have a Yanmar 2GM20 F engine (1988) and the Kanzaki KM2P transmission.

Can you pull the transmission? I would think so, if you have some tools and basic mechanical skills.

Lots of info and videos on YouRube to help you know what to look for…

This guy did a series…removing the trans, disassembly, and reassembly. He did the work on the transmission himself.

The first video will give you some good info on how to remove it…

Greg

I saw those. I’m just paranoid about the prop shaft slipping out and sinking the boat. Aside from that I’d have no qualms with doing anything myself.

Im waiting for a call from Yanmar about the availability of new or reman trannys or parts. I also have a somewhat nearby shop checking their inventory (pile) of trannys.

 

[Tally Ho]

I saw those. I’m just paranoid about the prop shaft slipping out and sinking the boat. Aside from that I’d have no qualms with doing anything myself.

Im waiting for a call from Yanmar about the availability of new or reman trannys or parts. I also have a somewhat nearby shop checking their inventory (pile) of trannys.

You could take a shaft zinc or even a big clamp and put it on the shaft so it can’t slide out…

greg

 

[dlochner]

Yes you can pull a transmission and not sink the boat. Just leave the coupling on the shaft, I'm pretty sure the coupling won't fit through the stuffing box.

The problem with a 40 year old transmission is getting parts to rebuild it, that model transmission may no longer be available. That was the case with my 30 year old Kanzaki transmission. The shop was able to identify a suitable transmission and 2 adapter plates that allowed the new transmission to mate with the engine. The transmission shop is your best bet. They can call Mack Boring (Yanmar Distributor) and talk to them about how to make it work.

 

[bonkle]

No dealers could help. I called many within a few hours. I then called the Yanmar Mastry Engine Center in Clearwater, FL. The service manager said to send it on over and 99% chance he can rebuild it. I'm going to pull and send it for inspection and hopefully hear good news. I asked if I was allowed to deal directly with them and he hinted that I technically couldn't, but he wasn't going to turn me away since there aren't any official routs for me to deal with them.

It's neat that I spoke to an official Yanmar decision maker. Wish car companies would do that.
Edit: well maybe they are a dealer. I don't think they are part of Yanmar now that I poke around a bit more.

 

[geek_guy]

I just went through this process a few months ago.

First the shaft should have a coupler on it which well not allow it to 'fall' out. I had a mechanic do the work and frankly was glad to have someone that knew the ins and outs. Though I might have been able to do it.

Second we took the tranni to the local Yanmar dealer who does many rebuilds a month. After disassembly they tried to get parts and were unable to find them. They found a suitable replacement. But then there needed to be an adapter plate. There were none available in the US. Backorder time frame was over 6 months from the factory in Europe. I called 20 + places and found the adapter and got it shipped into Florida. Mechanic came to install. Turned out the bolt pattern didn't match the engine. So we had to order a new coupler. Which had to be taken to a machine shop to be installed. It all did finally work but not easily or quickly.

 

[geek_guy]

ah, AND adding the adapter caused the shaft/prop to stick out further than the old one. So the mechanic recommended we get my diver to come and make sure there was adequate clearance.

 

[bonkle]

Here it is. Any tips?

 

[kloudie1]

Clean the shaft up so that when you slide it aft to clear the transmission, it doesn't tear up the packing material. Lube the shaft with a light oil before slipping it back.. Soak the coupling bolts/nuts with PB Blaster a week or so before you plan to unbolt it and slide it aft. Blaster is not good for rubber stuff, so be careful that it does not get anyplace except on the bolts/nuts.

 

[jssailem]

No worry about the shaft sliding out and off the boat. If the shaft is ok, you can uncouple the shaft from the transmission then remove the transmission for repair/rebuild. Follow @kloudie1's advice.

I would inspect the shaft that is under the stuffing box for corrosion. There looks to be some on the shaft where it enters the stuffing box. I did an inspection of mine and found replacement was required. You may discover that the shaft needs replacement. This would be the idle time to do that. Shaft replacement would require pulling the boat out of the water.

 

[American_Mainsail]

You could take a shaft zinc or even a big clamp and put it on the shaft so it can’t slide out…

greg

Good advice.

One or two stainless hose clamps on the prop shafts will do it. Loosen them and slide them up the shaft as you back the coupler off. You can loosen and slide them one at a time if you want to be really careful.

 

[American_Mainsail]

No worry about the shaft sliding out and off the boat. If the shaft is ok, you can uncouple the shaft from the transmission then remove the transmission for repair/rebuild. Follow @kloudie1's advice.

I would inspect the shaft that is under the stuffing box for corrosion. There looks to be some on the shaft where it enters the stuffing box. I did an inspection of mine and found replacement was required. You may discover that the shaft needs replacement. This would be the idle time to do that. Shaft replacement would require pulling the boat out of the water.

That's good advice from jssailem. I'd add that a propeller shafting place can usually offer repair options if the shaft is corroded/worn in some local places. They build back the worn areas with weldment, then turn the shaft back to perfection. This can save some coin over buying a new shaft.

 

[bonkle]

I have plans around Christmas to tackle this. I'm enlisting the help of a local charter captain who has done this several times. I found this awesome pic with a cutaway of the rubber boot. Does the boot hold the stuffing box assembly in place? How do I inspect the shaft under the boot and stuffing box- do I have to pull the boat and remove it?

 

[American_Mainsail]

You will need to pull the boat if you want to remove the stuffing box. That is the ultimate seal between the wet side (outside) and the dry side (inside).

 

[dlochner]

I have plans around Christmas to tackle this. I'm enlisting the help of a local charter captain who has done this several times. I found this awesome pic with a cutaway of the rubber boot. Does the boot hold the stuffing box assembly in place? How do I inspect the shaft under the boot and stuffing box- do I have to pull the boat and remove it?
View attachment 221936

Yes, the hose supports the stuffing box, that is why it is important use hose rated for a stuffing box and not just any old hose.

It is not possible to fully inspect the shaft while the boat is in the water, there is only about an inch of space between the prop and the cutless bearing, so maybe once the transmission is out you can pull the shaft forward an inch.

If you have a bronze shaft, there is a very high probability that it is seriously scored where the packing is up against it. Bronze is pretty soft and will score. It may be possible to repair the shaft, however the cost difference between the repair and a new Aquamet (SS) shaft will be pretty small.

If the transmission can not be rebuilt and needs replacing, it will probably be a ZF and it is likely the coupling will need replacing. Given the amount of corrosion on the shaft it may not be possible to remove the existing coupling without cutting the shaft.

 

[bonkle]

You will need to pull the boat if you want to remove the stuffing box. That is the ultimate seal between the wet side (outside) and the dry side (inside).

Yes, the hose supports the stuffing box, that is why it is important use hose rated for a stuffing box and not just any old hose.

It is not possible to fully inspect the shaft while the boat is in the water, there is only about an inch of space between the prop and the cutless bearing, so maybe once the transmission is out you can pull the shaft forward an inch.

If you have a bronze shaft, there is a very high probability that it is seriously scored where the packing is up against it. Bronze is pretty soft and will score. It may be possible to repair the shaft, however the cost difference between the repair and a new Aquamet (SS) shaft will be pretty small.

If the transmission can not be rebuilt and needs replacing, it will probably be a ZF and it is likely the coupling will need replacing. Given the amount of corrosion on the shaft it may not be possible to remove the existing coupling without cutting the shaft.

That's what I figured. I'm trying to avoid a $1500 tow, but am wide open to being talked in to it if this looks risky to do in water. Current plan is to just clean up the shaft, slide it back, rebuild trans, reinstall.

Replacement of transmission means a re-power. I really hope my rebuilder comes through. He's confident though.

Should I additionally plan to pull the boat, remove stuffing box and inspect? Probably will go ahead and replace stuffing box ($200). Maybe plan to replace prop shaft ($500) and cutlass bearing?... At a couple hundred a week in dry dock, shipping times matter.

 

[American_Mainsail]

That's what I figured. I'm trying to avoid a $1500 tow, but am wide open to being talked in to it if this looks risky to do in water. Current plan is to just clean up the shaft, slide it back, rebuild trans, reinstall.

Should I additionally plan to pull the boat, remove stuffing box and inspect? Probably will go ahead and replace stuffing box ($200). Maybe plan to replace prop shaft ($500) and cutlass bearing?... At a couple hundred a week in dry dock, shipping times matter.

I hear you. There's no "right" answer here. Based on the age of the boat, it certainly wouldn't hurt to go through that whole area, replace the stuff box, shaft log hose, packing (I like the Teflon packing - if you have it available), prop shaft, coupling, and cutlass bearing - all for piece of mind. I don't know what your cruising plans are (how remote you're planning on going in the near future factors into the equation). For storage, figure it will take double the time to get all the work done than you think it will (things always come up).

If it were me, I would start solving the main problem (the transmission). As you work on things (mainly as you start sliding that prop shaft back and forth), take a tally of the condition of things. If the prop shaft looks good, if the cutlass bearing is tight when you have your diver come, etc. I'd be more hesitant to start replacing everything.

Again, no right answer here. It's ultimately up to how much faith you have in the equipment and what surprises you find as you dig into things.

Edit: Looking at your pictures again, it's a little hard to tell but your shaft log hose is looking rough. It almost looks like it's starting to unravel. Take a hard look at that, if that hose fails you have a serious (sinking potential) problem.

 

[dlochner]

Replacement of transmission means a re-power. I really hope my rebuilder comes through. He's confident though.

Not necessarily. Contact Rick Neary, at East Coast Marine Transmissions and ask him. He has close ties Mack-Boring who are the East Coast Yanmar distributors. If the transmission needs to be replaced, not rebuilt, there are various adapter plates available so they can mate. He's an excellent transmission mechanic and a nice guy too.

http://www.eastcoastmarinetransmission.com/

 

[bonkle]

I hear you. There's no "right" answer here. Based on the age of the boat, it certainly wouldn't hurt to go through that whole area, replace the stuff box, shaft log hose, packing (I like the Teflon packing - if you have it available), prop shaft, coupling, and cutlass bearing - all for piece of mind. I don't know what your cruising plans are (how remote you're planning on going in the near future factors into the equation). For storage, figure it will take double the time to get all the work done than you think it will (things always come up).

If it were me, I would start solving the main problem (the transmission). As you work on things (mainly as you start sliding that prop shaft back and forth), take a tally of the condition of things. If the prop shaft looks good, if the cutlass bearing is tight when you have your diver come, etc. I'd be more hesitant to start replacing everything.

Again, no right answer here. It's ultimately up to how much faith you have in the equipment and what surprises you find as you dig into things.

Edit: Looking at your pictures again, it's a little hard to tell but your shaft log hose is looking rough. It almost looks like it's starting to unravel. Take a hard look at that, if that hose fails you have a serious (sinking potential) problem.

For boat use, I'm honestly at the level of a kid who found a deal on a toy. This is somewhat of an experiment in boat ownership. I think I'm doing pretty daggum well as far as ROI in fun and money (money in the boat itself)... but those slip fees! Makes me want to open my own marina. There's no flipping anything that lives in a slip.