yanmar clutch partially engaging

[bikedaft]

hi,

3gm30f about 10-12 years old

have noticed that at low revs the clutch only partially engages, ie the shaft turns, but vibrates a lot, when given more revs it all settles down. only when warm (have just done a 12h, 10h, and a 4h motor)

i think its a centrifugal clutch? so presumably there are a few pawls(?) and only some are engaging, at least initially.

gear oil changed at beginning winter, back in water 4 weeks ago. fine until long motor(s). oil level fine ie to line when dipstick placed in hole, but not screwed down.

thanks!

 

[bikedaft]

anyone? (bump)

 

[steve28]

They use cones as far as i know if its bumping at low revs the forward cone will either need relining or replacing but its expensive as always.


Steve

 

[bikedaft]

it doesn't look the hardest gearbox to take off, but what are they like to take apart?

also was told to use same oil in gearbox as for engine. can't remember grade (its on boat!) but from a yanmar dealer. take it this is correct? only ask cos an online manual says use different oil for engine and gearbox; http://www.motoren.ath.cx/download.php?filename=yanmar/Yanmar.gm-series.pdf

 

[pagoda]

it doesn't look the hardest gearbox to take off, but what are they like to take apart?

also was told to use same oil in gearbox as for engine. can't remember grade (its on boat!) but from a yanmar dealer. take it this is correct? only ask cos an online manual says use different oil for engine and gearbox; http://www.motoren.ath.cx/download.php?filename=yanmar/Yanmar.gm-series.pdf

There are two different series of gearboxes out there.


Chapter 10 in the Yanmar Workshop manual...
KM series - use regular SAE motor oil - as stamped on the serial number plate
This is a cone-clutch gearbox

Chapter 11 in the Yanmar Workshop manual...
KBW series - use ATF - also marked ATF on the plate
This uses a plate style clutch

All ATF I have ever met is dyed red.
The manuals are pretty explicit about stripping down - and well illustrated.

Graeme

 

[bikedaft]

its a km3p gearbox. (kanzaki) ie cone clutch. guess it does not owe me anything its been in there for 10 - 12 years, just wondering if it was something to do with me changing the oil etc. (possibly never been done before, not long bought the boat). will check linkages, and try and leave it till the winter...

plate says use 20/30w CD oil

found a very detailed manual at http://www.motoren.ath.cx/menus/yanmar.php 60mb tho!

cheers for your replies

 

[bikedaft]

(followup)

nothing to do with gearbox, the gear selector/throttle lever jammed shortly after. alum gear cogs in a salt water environment. mmm. it had been misaligning the gear selector cable.

gearbox been fine ever since

thanks again

 

[charles_reed]

Having had loads of grief with the cone-clutch fitted to a 2GM, which started stuttering at low revs and finally would only allow me to reverse.

I stripped the gearbox out between tides on the beach at Castletownberehaven to find that the selector forks had worn on one side (forward).
It was a simple matter to reverse the fork - I thought forward more useful than reverse - but both then worked so I was very happy.

The list of reasons I got from Barrus were:-
insufficient travel on the cable, glazed cone (through using wrong oil) or stripped layshaft.