No astern power

[Portland Billy]

My Volvo AD41 wont go astern.
It revs normally and clutches in ahead OK.
But try to engage astern is like driving a car with a slipping clutch, it eventually gives some power but nothing like it should with the engine revs.

Any ideas ?

 

[gordmac]

Oil level ok?

 

[Portland Billy]

Oil level is fine.

 

[Sumara of Weymouth]

Maybe, if the engine and gearbox are fine, then perhaps you have sheared the keyway. I had this once. As the prop has a taper fit, in forward gear it will grip the shaft even without a keyway but in reverse, if there is any slack in the bolt then the prop will shunt off the taper and can slice through the keyway. Most keyways seem to be brass rather than bronze and can corrode quite easily. Perhaps worth checking and easy to resolve.