I have a Hurth transmission on an M25XPB from 1990. I recently broke my strut and the prop hit the hull and broke. I got a new shaft, coupler, strut, prop, etc.
When I put it back together the ENTIRE shift/throttle assembly got a thorough re-do with all new parts. The tranny worked pretty well...at first. Then on the way home from the boatyard I noticed it wouldn't do any more than about 1500 RPM (my tach wasn't working at that time. I could make it rev higher but then the tranny would make a noise and lose traction and back down to the aforementioned 1500 or so. BTW, I changed the prop from a MARTEC ELLIPTIC RH13,14 to a fixed three-blade prop, which is 13 x 15, I got on EBAY. I know the higher pitch can cause issues, but the only issue I find is that I get full hull speed with only 2000 RPM. After totally tweaking the cables to work perfectly and trying the transmission without the shaft connected and without the cable connected it got full RPM's at the dock. I finally figured that it was slipping. I emptied it and added paint thinner, ran it for half an hour in all the different ranges and then drained it and added the required amount of ATF. It seemed to work perfectly AT THE DOCK. But once I took it out and sea-trialed it I got the same thing as it was doing before. It especially didn't like just giving it full throttle. Slowly raising the speed with the speed of the boat worked fine... mostly.
My question is: has anybody else had this problem and if so, were you able to remedy it or am I just doomed to buy a new tranny? I believe I've exhausted all the options at this point.
Thank you!
When I put it back together the ENTIRE shift/throttle assembly got a thorough re-do with all new parts. The tranny worked pretty well...at first. Then on the way home from the boatyard I noticed it wouldn't do any more than about 1500 RPM (my tach wasn't working at that time. I could make it rev higher but then the tranny would make a noise and lose traction and back down to the aforementioned 1500 or so. BTW, I changed the prop from a MARTEC ELLIPTIC RH13,14 to a fixed three-blade prop, which is 13 x 15, I got on EBAY. I know the higher pitch can cause issues, but the only issue I find is that I get full hull speed with only 2000 RPM. After totally tweaking the cables to work perfectly and trying the transmission without the shaft connected and without the cable connected it got full RPM's at the dock. I finally figured that it was slipping. I emptied it and added paint thinner, ran it for half an hour in all the different ranges and then drained it and added the required amount of ATF. It seemed to work perfectly AT THE DOCK. But once I took it out and sea-trialed it I got the same thing as it was doing before. It especially didn't like just giving it full throttle. Slowly raising the speed with the speed of the boat worked fine... mostly.
My question is: has anybody else had this problem and if so, were you able to remedy it or am I just doomed to buy a new tranny? I believe I've exhausted all the options at this point.
Thank you!