Yanmar gearbox experiences??

capnsensible

capnsensible

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Ive got a boat with a 3GM Yanmar unit plus a standard gearbox.

This has been getting increasingly rattly over the past couple of months, but only in ahead and up to about 1200 revs, after that the rattle and vibration smoothes out.

Anyone else had a similar problem??

Prop is ok, cutlass bearing replaced in January, alignment good. Only happens slow speed ahead.

Took the gearbox off today, plus driveplate. Local agent is doing a bit of tooth sucking so thought I would ask here.

Driveplate looks like black sikaflex has been put on the springs, seems a bit odd. Small engine oil leak into bell housing but drive plate dry.

Drive plate is £450, gearbox over three flippin grand!

Any tips much appreciated, ta in advance.

CS
 
Find a decent dealer. Theres nothing in the gearbox that is beyond reasonable cost repair. Try cellar marine porthallow- they mostly deal with fishermen who dont stand for tooth sucking idiots.
 
birdseye said:
Find a decent dealer. Theres nothing in the gearbox that is beyond reasonable cost repair. Try cellar marine porthallow- they mostly deal with fishermen who dont stand for tooth sucking idiots.
Click to expand...

Top tip but there is only one dealer where I live and parts have to arrive on an aeroplane!!
 
If its like the one behind our 3JH2E it is pretty simple.

Cones and mating outers.

Selection is by a simple push/pull toggle working in a groove in the back to back cones IIRC.

If its rattling, something must be worn or slack.

There is a gear train-epicyclic probably-that would be my first place to look.

Good Luck.
 
A true story.. Friends with a knackered box ill- installed to drive a Wharram cat from deck level, removed the unit and part dismantled it and THEN took it home to Holland instead of getting involved with the local Iberian outfit of questionable repute... on the plane..As unweighed hand luggage back in the day when you could..
He simply restitched one of his wife's pretty shoulder bags with copious amounts of webbing.. Oh how we did larf.. Worked too. 50kilos maybe?
 
Have sourced a new drive plate rather cheaper than the 450 quid Yanmar want. Have also flushed out gearbox and it does have some fine metal swarf, eek.

Trouble is, the cost of Yanmar parts for a gearbox rebuild is extortionate. You also got to order right shims and a whole bunch of other stuff that is 'not in stock'.

Have found the workshop manual on line, its not quite as simple as it looks!

May yet have to bite bullet and get a new box, at least it comes guaranteed........


Workshop manual here: http://www.sv-zanshin.com/manuals/yanmardieselinboardshopmanualgeneral.pdf
 
All gearboxes will have fine metal swarf to some extent after use. That may not be a problem.

How many hours on the unit? Our power unit has in excess of 3500 hrs. and is fine.

If it dismantled and all the bits are clean and dry, careful inspection should highlight any severe wear areas.

As I said before, the gear train is the most likely to rattle. If that has gone, replacement will probably be your best option.
 
Thanks again! Now 16 years old and has taken a fair old hammering so I may need to do the decent thing. The season of Bank Holidays here every 5 minutes is not helping.....
 
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