Hi all, first time poster long time reader.
We have just bought a new boat
(for us) with a Yanmar
4jh4ae and SD50 saildrive
with a flexifold 3 blade
. The combo has 550 hours on it. The last week it intermittently has not been engaging in forward drive. Sometimes it engages in both forward and reverse, other times only reverse, and forward only engages at high revs (with a clunk), or only partially engages, and other times it doesn't engage at all no matter what. I've dived on it several times, and on those occasions (n=2), when in forward with the prop spinning at idle, and revs are increased, the prop starts to increase speed but then slows down again almost immediately, despite the increased engine
revs. However, on occasion it will still provide full power and drive the boat
forward at >6 knots as expected.
The Morse, linkages and cables
all appear to function well, and a mechanic
has just adjusted them thinking this could be the problem, however the fault is still there. The engine
box and clutch
makes no unusual noises. The prop seems to be properly fitted, not loose, and folding and functioning correctly.
I understand the cone clutches on these need regular re-lapping, but imagine if the clutch
was degraded this should result in almost complete loss of drive - which is not what we experience some times. I'm bamboozled!
I'm hoping to hear from the community whether these symptoms sound like the cone clutch, or possibly something else (the prop slipping on the shaft?)? All thoughts greatly appreciated, as we are currently cruising through the Med on our way back to New Zealand
so don't have our usual service
people to call on, and budget
constraints require as much self-resolution as possible!