Yanmar 3gm30f transmission swap

[masonc]

I'm going to replace my transmission as I find it was not engaging properly. Is it easy to do with removing the engine or should I man up and take it all out. I'm on the hard in St. Kitts and I have my own crane.

[TheOffice]

changed the tranny on a 4HTE. Needed a second set of hands to get it out, but it is substantially larger than yours. If you have access, no need to \pull the engine.

[roverhi]

The Kanzaki transmission is actually quite light and relatively easy to manhandle. Having said that, I changed my transmission after pulling the engine with it setting on the cabin sole. Had the galley torn apart so it was easy to pull the engine for access.

[masonc]

Weight is not an issue, I have a 2 ton crane on my truck that can get right above the engine hatch. Access is not an issue, the hatch is large enough to take the engine out, nothing needs to be disassembled. It's one of the great joys of this boat.

[masonc]

Is there a difference between my KM2P and a KM2P-1?

[Drumroll30]

You say its not engaging properly, did you check the Morse cable? Is it adjusted according to the Yanmar owners manual? This easy check could save you lots of time and money before you go straight to replacing the tranny.

[Badsanta]

Yes, check your shifting cable, they can slip out of adjustment.

[masonc]

Good tips

[lateral]

Left mine in and have worse access than you, by sound of it. But I did break a bunk lid with my knee lifting it out. Actually whole thing was easy. They are light. (ish)
Machined tail shaft & installed smaller oil seal as was leaking owing to minor pitting.

[RaymondR]

I had a problem with the gearbox on a 3GM30 not engaging, disassembled it and found that the problem was that the conical spring which preloads the clutch cone assembly to keep everything parallel had worn slightly into the thrust washer it bears against. Reversed the thrust washer so that the un-worn side was against the conical spring and never had another problem with it.

[masonc]

Originally Posted by RaymondR

I had a problem with the gearbox on a 3GM30 not engaging, disassembled it and found that the problem was that the conical spring which preloads the clutch cone assembly to keep everything parallel had worn slightly into the thrust washer it bears against. Reversed the thrust washer so that the un-worn side was against the conical spring and never had another problem with it.

Good info, thanks. Did you have any reference materials for disassembly, such as a repair manual? Did you need special tools? Any advice appreciated. My haul out location is pretty isolated.

[pcmm]

The trans on a 3GM30F is pretty light. In comparison, the KM4A trans for the bigger 4JH series only weighs 38lbs. My 14 YO son can easily move it around. Just make sure you have at least 4-6 inches of space behind the trans, remove the bolts and then just slide it aft until it disengages.

Have you checked the shift linkage first? disconnect it from the cable and then shift and see if it goes into gear correctly. the cone wear a bit over time and need to be resurfaced ( not hard)

Removing and reinstalling is pretty easy. I just smear a light coating of grease on the input splines in an attempt to prevent them freezing to the damper plate over time.

[RaymondR]

Originally Posted by masonc

Good info, thanks. Did you have any reference materials for disassembly, such as a repair manual? Did you need special tools? Any advice appreciated. My haul out location is pretty isolated.

It's probably ten or so years since I did the job but I don't recall it requiring any special tools.

I had a shop manual which I had purchased when I bought the engine but seem to recall it was a routine disassembly and that having the manual was not a necessity. It is important to get everything back as it was except the thrust washers you will be reversing. There is a procedure for correctly spacing and shimming the clutch/cone assembly but if you are re-using all the original parts it does not require re-doing.

There is a big nut holding the assembly onto the shaft. I held the assembly in a vice and used an 18" pipe wrench to undo and replace the nut other than that only standard sockets and spanners are required.

[masonc]

I'm keen to rebuild myself if adjusting the controls does not solve the issue, but...
There's always a but with boats,
I won't know if there is still a problem until I launch after hurricane season. If there is, I'll have to haul again, order parts, wait a month for them to arrive, then rebuild the tranny. My workshop is in Anguilla, boat it in St. Kitts.
If I check the controls and don't see a problem, a transmission replacement may be the most expedient choice.