Help with gearbox problem please.

[Oscarpop]

Can we get some advice about our gearbox please. We have a Yanmar km35p attached to a Yanmar 3j5he. 7 years old. 1200 hours.

This morning we tied up to the fuel pontoon and when we tried to leave the engine had little drive in forward gear for about ten seconds, then all of a sudden the drive would engage and we would get the power we would expect from the revs we were applying to the engine.

The problem doesn’t happen in reverse. Only in forward.

It’s also an intermittent problem. Sometimes it engages straight away, and sometimes you have to wait 5-10 seconds.

I have checked the gearbox oil and it was low but still within normal parameters.

I have checked the morse control and manually engaged the gearbox from within the engine bay. Same problem.

I have checked the prop. No fouling and it turns freely, as does the shaft.

I now am at the conclusion that the gearbox or the clutch cones are worn and not engaging.

Have I missed anything?

 

[RichardS]

AS the same problem occurs when the actuating arm is operated manually, the problem must be within the gearbox, and worn cones, assuming your gearbox uses that system, is certainly very likely.

Richard

 

[VicS]

Can we get some advice about our gearbox please. We have a Yanmar km35p attached to a Yanmar 3j5he. 7 years old. 1200 hours.

This morning we tied up to the fuel pontoon and when we tried to leave the engine had little drive in forward gear for about ten seconds, then all of a sudden the drive would engage and we would get the power we would expect from the revs we were applying to the engine.

The problem doesn’t happen in reverse. Only in forward.

It’s also an intermittent problem. Sometimes it engages straight away, and sometimes you have to wait 5-10 seconds.

I have checked the gearbox oil and it was low but still within normal parameters.

I have checked the morse control and manually engaged the gearbox from within the engine bay. Same problem.

I have checked the prop. No fouling and it turns freely, as does the shaft.

I now am at the conclusion that the gearbox or the clutch cones are worn and not engaging.

Have I missed anything?

Either the clutch cones or the shifter worn, item #13 in this diagram https://www.yanmarshop.com/catalogu...8/clutch-km-series-km35p-fig-9-control-device ,
Hopefully only the latter as that is accessible without tearing the whole gearbox apart

 

[black mercury]

What oil have you been using in the box?

 

[VicS]

Service manual here if you fancy your chances with the tools.

http://www.hughes38.com/wp-content/uploads/2016/02/KM-Series-Service-Manual-incl-KM35P.pdf

Read it. IIRC there is some scope for adjustment of the shifter which might solve the problem in the short term

 

[Oscarpop]

What oil have you been using in the box?

No idea, the Yanmar engineer that did the first service left me about a litre of gearbox oil.

 

[Oscarpop]

Service manual here if you fancy your chances with the tools.

http://www.hughes38.com/wp-content/uploads/2016/02/KM-Series-Service-Manual-incl-KM35P.pdf

Read it. IIRC there is some scope for adjustment of the shifter which might solve the problem in the short term

Cheers,

I’m fairly sure it’s a worn clutch cone. Problem is we are currently in France which is shut for August.

Have an engineer coming out on Wednesday. Pretty sure he will simply recommend a new gearbox.