Gearbox grind when engaging

[Sneaky Pete]

I don’t know if this is a problem or just normal. Yanmar SD20 saildrive when engaged in either forward or reverse there is a bit of a grinding noise when gears engage. Does the gearbox have any adjustment that would eliminate this.

 

[RichardS]

I assume that the SD20 is full to the mark with 80W90 gear oil?

Richard

 

[macd]

'Morse' control adjusted correctly? It should fully move the gear selector lever before increasing revs. The prescribed amount of lever travel, at the gearbox end, will be described in the handbook.

 

[Sneaky Pete]

The oil is new and to the level, the engine idles at about 600rpm when engaged with no increase in revs there is a grinding noise just when the gears are aligning. Is there some kind of cone that acts as a clutch in this set up that could be adjusted.

 

[RichardS]

I think the SD20 is a simple dog clutch so it's engaged or not engaged, which is why it engages with a bit of a thump, although I wouldn't describe it as a "grinding" noise.

Richard

 

[VicS]

I don’t know if this is a problem or just normal. Yanmar SD20 saildrive when engaged in either forward or reverse there is a bit of a grinding noise when gears engage. Does the gearbox have any adjustment that would eliminate this.

The oil is new and to the level, the engine idles at about 600rpm when engaged with no increase in revs there is a grinding noise just when the gears are aligning. Is there some kind of cone that acts as a clutch in this set up that could be adjusted.

The SD 20 uses, as Richard says , a dog clutch. Engagement of forward or astern gear should therefore be made with a positive action, not slowly , before the revs increase above idle. Slow engagement will cause wear of the dogs. If the engine revs increase before the clutch engages adjustment of the control linkages is required.
id not expect to hear grinding noises, just a solid clunk as the clutch engages, The SD50 OTOH has cone clutches and the manual warns that a grinding noise as they engage is normal.

The grade of oil, ( 10W30 or 80W90 gear oil) depends upon the engine to which the drive is fitted (GM or YM )

 

[RichardS]

The grade of oil, ( 10W30 or 80W90 gear oil) depends upon the engine to which the drive is fitted (GM or YM )

From memory, I think the lower weight oil is only for the 10HP GM, presumably because it doesn't have enough power to spin the thicker oil?

Richard

 

[Tranona]

From memory, I think the lower weight oil is only for the 10HP GM, presumably because it doesn't have enough power to spin the thicker oil?

Richard

Yes, and a switch to stop the alternator charging until the engine is warm. All intended to reduce the load so you can actually start the meagre collection of horses!

 

[Sneaky Pete]

I think one of the problems is that I am being too gentle when engaging drive. Possibly a bit more forceful as previously said. Will try at weekend.
I may even remove the selector cable at the gearbox and try by pushing level by hand.
Thanks for replies.