Yanmar Gearbox

[mawtty]

My KANZAKI KM3-A
is very noisy as I increase power. Otherwise works fine.
1.I want to relpace it.
Does anyone have a re-built unit or one in good condition to sell?
2. How easy is relpacing bearings and seals if I do it myself?
mawtty

[Compass790]

I"d PM skipperpete to ask that question or check workshop manual if no-one chimes in.
Our Kanzaki gearbox looked ralatively straightfwd to do that but not the same model

[keith001]

Before you rebuild/replace drain the fluid, replace with synthetic. Operate for an hour or so shifting forward to reverse. Inspect the fluid, and if very dark change it again. It may get quiet after about three changes. Can’t hurt

[tkeithlu]

Plus one to Keith001's answer. The problem could be a simple as low oil.

If you want to tackle rebuilding it yourself, it's not a very complicated transmission, just two shafts and a cone clutch, but:

Make sure you've got a source of a replacement in the worst case senario of making a total mess of it.

Make sure that you've got a source of parts. I don't think that tranny is still made, but it's current enough for parts to be available.

Get an exploded view of the parts. That's a big help in reassembly.

Photograph every step as you disassemble, and lay out the parts in the order they go back in.

You will need to pull and drive bearings. That takes just a little bit of skill. Use a wood dowel, tap-it hammer, and patience if it's your first time doing that.

Your goal is in part to repair your tranny. It is also to learn your way around such mecahnical challenges. A total failure is not a total failure because you learned a lot.

[Gary Mc]

I had mine repaired professionally about 5 years ago. I should have done it my self but wanted it done quickly. Unfortunately it took the repair shop 5 weeks to get a new cone clutch from Yanmar. So much for getting it done quickly.
I am in Canada and they only ship here from the States once a month so make sure you have the seals and bearings on hand. Although they will be standard items so you could get them from an automotive store etc.


It should be fairly straight forward, I would do it myself next time.


Good Luck

[Teknishn]

Agree with Keith001's answer as well as a starting point.

If that doesn't solve the problem, I'd remove and disassemble the gearbox and inspect the cone clutch and drive gears. With the cone clutch being made of bronze/nibral and the gears being steel, glazing on the steel mating surfaces between the cone clutch and gears can occur.

Another thing to check is the shifter mechanism. Is it engaging correctly? Might be that the shifter "tab" is worn and not fully shifting the cone clutch (check your manual for measurements and tolerances).

I've rebuilt KM-2's and 3's. Not difficult but takes some mechanical skills as tkeithlu stated. I source my parts from J-Way Enterprises. https://www.j-wayent.com/Diesel-Engi...ituate-MA.html