jet problem??

[dukey37]

hi, looking for some help/advice please? have a yanmar diesel driving a hamilton jet. was out last weekend cruising going well no proplem slowed down to chat to a mate hitting the other way kept engine running moved off after a few minutes and she accelerated to half about 1/3 of her speed then no more engine would rev no problem but she would not move any quicker. checked for blockages etc. any ideas please?

[Mollers]

A blockage over the intake grill could do it, seaweed can also block up a jet a treat.

[dukey37]

hi, we have all that checked!!

[codprawn]

Does your system use a clutch or hydraulics? If it's a clutch it could be slipping under load - if it's hydraulic the fluid could be cavitating in the pump.

[dukey37]

its hydrolics, could you explain what to do and i could give it a go. thanks. its a BH weekend here so it would be great to be able to get out.

[dukey37]

we still have not our problem sorted?? anyone have any other ideas.. please..

[codprawn]

Sorry for the delay - just seen a bloke who works on these - he said it could be a sheared drive to the hydraulic pump. Sometimes the woodruff key gives way and allows the shaft to spin under load giving problems like a slipping clutch. Could also be a rubber spline drive that is slipping.

[matt h]

try to turn the impellor from the rear and hopefully the drive shaft will turn at the same speed, if not, there lies your problem!!

[dukey37]

thanks a lot lads i will check out your tips over the weekend.. i appreciate you both getting back to me.