Yanmar transmission
- Thread starter kair
- Start date
- Status
I would disconnect the shifter from the transmission at the transmission. Then try shifting by hand (make sure the engine is off, or the boat tied well if running). If it shifts easily by hand, and it should, the problem is in the linkage or cables.
If it is tough to shift by hand at the transmission, then you have to identify which reverser you have, should be a tag on the Yanmar or bell housing to do so.
If it shifts easily at the trans, then you need to follow the cables back and see if any kinks or bare wires are showing or broken strands at the ends. Could be the shifter in the cockpit. See if they all move easily while not connected.
SHould get you to a spot where you know it will be cheap or expensive (cables/shift or internal to the trans).
If cables, pretty easy to repair, shifter a tad tougher, transmission tougher yet.
Since it is tough both ways, I would suspect cables or linkage binding.
best of luck
If it is tough to shift by hand at the transmission, then you have to identify which reverser you have, should be a tag on the Yanmar or bell housing to do so.
If it shifts easily at the trans, then you need to follow the cables back and see if any kinks or bare wires are showing or broken strands at the ends. Could be the shifter in the cockpit. See if they all move easily while not connected.
SHould get you to a spot where you know it will be cheap or expensive (cables/shift or internal to the trans).
If cables, pretty easy to repair, shifter a tad tougher, transmission tougher yet.
Since it is tough both ways, I would suspect cables or linkage binding.
best of luck
Dito kd3pc's comment
It could also be the neutral lockout. the collor that you pull toward the ball that allows the shifter to be moved from neutral. It could be hanging up and making the shifter hard to move.
If this is an intermittent problem then it is most likly the shift lever mechanisum. Unlikly that both forward and reverse in the transmission would go at the same time.
Good luck
It could also be the neutral lockout. the collor that you pull toward the ball that allows the shifter to be moved from neutral. It could be hanging up and making the shifter hard to move.
If this is an intermittent problem then it is most likly the shift lever mechanisum. Unlikly that both forward and reverse in the transmission would go at the same time.
Good luck
refering to kd3, the transmission is very stiff at the transmission bell. i am thinking of removing the transmission at the flywheel. Is this possible with the engine in place or do I have to remove the engine. also, when I decouple the prop shaft, any ideas on how to secure the shaft from causing the cutless bearing to tear.
thanks
steve
thanks
steve
Assuming you have a standard coupling flange when you un-bolt the shaft flange from the transmission the shatf flance will still be attached to the shaft. They usually don't come off easily. You can then slide the shaft back a few inches. You can't move it back too much because the prop will probbably hit the rudder. There is no need to take the flange off the shaft unles you need the room to remove the transmission. On my H-27 there was not enouygh room to unbolt the transmission even with the shaft removed.
I took the bolts off of the top of the motor mounts, put a 2x4 over the hatchway and used a come-along (a hand winch used to install chain link fences- form Home Depot @about $25) to lift the engine up which allowed me to swing it around 180 degrees and remove the transmission.
If you are concerned with the shaft you can put a hose clamp on the shaft behind the shaft flange and tighten it down as a temporary measure to hold the shaft in place but I don't think you'll loose the shaft beacue the flange should prevent it from slipping out and the prop which is on the other end will probably hit the rudder first.
I took the bolts off of the top of the motor mounts, put a 2x4 over the hatchway and used a come-along (a hand winch used to install chain link fences- form Home Depot @about $25) to lift the engine up which allowed me to swing it around 180 degrees and remove the transmission.
If you are concerned with the shaft you can put a hose clamp on the shaft behind the shaft flange and tighten it down as a temporary measure to hold the shaft in place but I don't think you'll loose the shaft beacue the flange should prevent it from slipping out and the prop which is on the other end will probably hit the rudder first.
Steve
a while back they were called reversers instead of transmission..sorry for the confusion.
You will need to identify the trans model number and post that here. My trans is a "clutch disc" type...a lot like an old three speed car transmission...Yanmar also provided some "cone style" transmissions. Each has it's own peculiarities.
In my case simply changing the gear lube and installing the correct type per the Kanzaki Manual did more to improve my shifting and neutral location than the mechanical fixes some did.
That being said, the first thing I would do is to change the gear lube and then run the trans under engine power for a couple of hours and then change it again. It is amazing how inexpensive this fix can be.
If after that it still binds, then we need to look at the drawings for your transmission and see where things could bind up.
a while back they were called reversers instead of transmission..sorry for the confusion.
You will need to identify the trans model number and post that here. My trans is a "clutch disc" type...a lot like an old three speed car transmission...Yanmar also provided some "cone style" transmissions. Each has it's own peculiarities.
In my case simply changing the gear lube and installing the correct type per the Kanzaki Manual did more to improve my shifting and neutral location than the mechanical fixes some did.
That being said, the first thing I would do is to change the gear lube and then run the trans under engine power for a couple of hours and then change it again. It is amazing how inexpensive this fix can be.
If after that it still binds, then we need to look at the drawings for your transmission and see where things could bind up.
Guys,
Thanks for the ideas on this forum/topic. I am going to try to remove the transmission after this season. I will try kd3pc's suggestions and change gear lube, any suggestions??, and if that does not work, then the disassembly begin.
Steve..
Thanks for the ideas on this forum/topic. I am going to try to remove the transmission after this season. I will try kd3pc's suggestions and change gear lube, any suggestions??, and if that does not work, then the disassembly begin.
Steve..
Has the stiffness been a recent development for you... or has it always been?
I ask because the transmission handle at my pedestal (probably same as you -- 2QM20 on a 1980 Hunter 36) has always been very firm to operate. When I've had the shift housing on pedestal open/apart, it always looked to me that the Yacht Specialties design doesn't afford very good leverage. I always assumed that was the cause. As quite a bit of strength is need to engage and disengage the transmission, I do worry that something in the cable and linkage system will slip loose or break eventually.
That said, in the four years I've owned my boat, the stiffness between forward, neutral and reverse has remained the same.
My 2QM20 Factory Service Manual is on my boat. But I have at home a 1GM10/2GM20/3GM30 manual (which for some reason was on my boat when I bought it). The four attached photo's from the transmission chapter give a general description/drawing of the shifting mechanism and info about force required to engage and disengage the clutch, both at the housing and at the the shifting lever on the pedestal. Maybe this will help. The force specs are for an operating rpm of 1000. I see from your profile that you are an engineer. I expect that you'll do a much better job of interpreting the info I could.
I ask because the transmission handle at my pedestal (probably same as you -- 2QM20 on a 1980 Hunter 36) has always been very firm to operate. When I've had the shift housing on pedestal open/apart, it always looked to me that the Yacht Specialties design doesn't afford very good leverage. I always assumed that was the cause. As quite a bit of strength is need to engage and disengage the transmission, I do worry that something in the cable and linkage system will slip loose or break eventually.
That said, in the four years I've owned my boat, the stiffness between forward, neutral and reverse has remained the same.
My 2QM20 Factory Service Manual is on my boat. But I have at home a 1GM10/2GM20/3GM30 manual (which for some reason was on my boat when I bought it). The four attached photo's from the transmission chapter give a general description/drawing of the shifting mechanism and info about force required to engage and disengage the clutch, both at the housing and at the the shifting lever on the pedestal. Maybe this will help. The force specs are for an operating rpm of 1000. I see from your profile that you are an engineer. I expect that you'll do a much better job of interpreting the info I could.
Attachments
Last edited:
The transmission on my 2QM20 takes the same stuff as the engine -- 30w diesel engine oil. If I recall correctly the name plate on the transmission housing will specify. In the GM series service manual that I referenced before, for the two types of transmissions installed on them, KM2 and KM3, they use "SAE 10W-30, CC Class". (although probably by now the CC class is outdated by a more modern improved formulation ..)
Here is a photo of my old Yanmar 2GM20F transmission specification plate. It was much easier to photo it and look at the photo than hang upside down in the bilge to read it. It tells you Oil quantity and recommended weight. Not all 2GM20 transmissions are the same so never assume. This picture is from a 1985 Yanmar model.
Attachments
njsail:
Yes, you are right about "never assume". My bad. Probably even for much the same transmission, depending on the year made and the evolution of oil specifications and designations and perhaps reports of in-service experience, the oil on name plates might be different. Actually in support of your point, I just observed that in the GM series service manual that I have (its an official Yanmar publication), although the transmission chapter is very clear that the oil type is SAE 10w30 CC for a KM2 transmission, in their example of a transmission name plate for a KM2, it specifies SAE 20/30 HD. Same as your nameplate.
As for taking a photo being the easiest way to capture the nameplate data, my experience corresponds. The difficulty in viewing the nameplate for my 2QM20 might be the reason that a PO had the wrong manual on board. Also my surveyor listed the engine instead to be a 2GM20. It wasn't until one day a few weeks after I took possession of the boat, when I wanted to get a little familiar with my engine, that I noticed that things didn't quite match up between the manual and the physical engine. Eventually I discovered where the nameplate was, but because it was on the same side as an immovable bulkhead, it was was impossible to read by eye. It took several attempts with a digital camera on close-up mode to capture the detail. That's when I learned I had a 2QM20!
(p.s. I imagine that SAE 20/30 might be somewhat difficult to find these days?)
Attachments
Steve (and another idea for Kair):
Thanks for this link to the Yanmar lubricant spec table.
The original post for this thread was because shifting had become very stiff for Kair ...
I notice on the lubricant table, there's a "#" next to the description for several models. "#" = "These models can have a stiff/heavy gear selection& vague neutral selection use "Morse Supreme" or equivalent low friction 33c type cables." The "#" applies to the KBW10, which is the model that was mated with my 2QM20H on the 1980 Hunter 36. (Photo of the transmission nameplate is below.) So it seems that stiffness is a characteristic of my transmission right from the get-go.
Kair: Just a thought about something else that could be related. On the pedestal, the bracing and attach points for the shift/throttle cables are molded into the plastic control lever housing. I read about reported problems to this design right after I bought my boat. With age and thousands of gear shifts, stress cracks can develop at the attach points or even a complete break-off. Maybe its possible that if the cable mount isn't attached firmly to the housing anymore, the leverage effect through the handle has been compromised. Since I was doing another project (cockpit floor core repair) that caused me to remove the entire pedestal, the shift lever housing was easily separated from the rest of the pedestal. Visual inspection revealed noticeable stress cracks had formed. The housing was in reasonable shape otherwise. I was able to repair by reinforcing the weak areas by folding SS sheet metal around them and then filling the whole void space of the housing with West Systems epoxy to make it essentially a solid block of plastic. This was my first ever mix of a large batch of epoxy. I had a few very anxious minutes when the mixture began to get real hot and smoke during the curing. Fortunately I was outside and it settled down before ruining the plastic housing. Next time smaller batches layered up.
Thanks for this link to the Yanmar lubricant spec table.
The original post for this thread was because shifting had become very stiff for Kair ...
I notice on the lubricant table, there's a "#" next to the description for several models. "#" = "These models can have a stiff/heavy gear selection& vague neutral selection use "Morse Supreme" or equivalent low friction 33c type cables." The "#" applies to the KBW10, which is the model that was mated with my 2QM20H on the 1980 Hunter 36. (Photo of the transmission nameplate is below.) So it seems that stiffness is a characteristic of my transmission right from the get-go.
Kair: Just a thought about something else that could be related. On the pedestal, the bracing and attach points for the shift/throttle cables are molded into the plastic control lever housing. I read about reported problems to this design right after I bought my boat. With age and thousands of gear shifts, stress cracks can develop at the attach points or even a complete break-off. Maybe its possible that if the cable mount isn't attached firmly to the housing anymore, the leverage effect through the handle has been compromised. Since I was doing another project (cockpit floor core repair) that caused me to remove the entire pedestal, the shift lever housing was easily separated from the rest of the pedestal. Visual inspection revealed noticeable stress cracks had formed. The housing was in reasonable shape otherwise. I was able to repair by reinforcing the weak areas by folding SS sheet metal around them and then filling the whole void space of the housing with West Systems epoxy to make it essentially a solid block of plastic. This was my first ever mix of a large batch of epoxy. I had a few very anxious minutes when the mixture began to get real hot and smoke during the curing. Fortunately I was outside and it settled down before ruining the plastic housing. Next time smaller batches layered up.
Attachments
- Status