Just finished having the bottom done, props tuned up, new cutlass bearing. I still have a vibration at dead slow on the starboard side. bump it up a 100 turns, it goes away. Only thing left I can think of is engine alignment. Anyone have any other ideas?
Thanks, Mark
I have a noise at dead slow after transmission is warmed up, does not happen when pulling out of slip. Checked props, Watched shaft (not fun position underway, use ear plugs), checked alinement, changed trans filter and trans fluid. Had mechanic on boat just before haul out. ZF trans, starboard side only. Was told that is normal sound. Noise is a soft knocking on my boat. Not sure if he was right on not. 50 RPM up and it goes away.
I don't have a noise, I have a vibration. Shift to neutral it goes away. Only at dead slow.
mine makes no noise in neutral. Vibrations usually get worse with more rpms.
ZF manual shows how to check alinement. Easy to do. Might check it out.
If you need to adjust, motor mounts needs to be adjusted. Does not look to be a fun project. Owners manual has section on that also.
Hurth transmissions are known for a rattle at idle / neutral speeds unless the engine is running perfectly smooth. A vibration is something else. Take a look at your old cutlass bearing. Is it worn evenly or off to one side. You could have a bent or misaligned strut putting a bow in the shaft. Is the distance between the cutlass bearing and the prop greater than the shaft diameter? This can cause a whipping action and shaft fracture. Did you put a dial indicator on the shaft and check the run out? Check it at the prop taper and midway to the stuffing box. Have you checked the engine alignment after the boat has been afloat and run for a while? An alignment while on jack stands is only a rough alignment. How about a check of your engine mounts.
Capt. George
Hmmm, vibration at idle, but not at higher RPMs? Rare, but I have seen it. I agree, engine alignment would be my first check. My second would be check the props. It is very common when props are first installed that they get hung up while they are tightening the nuts and they don't get fully seated on the shaft (this is why props should be lapped on with lapping compound and not just throw on and tightened). What happens is the prop wobbles at low RPM, but as you speed up, the force of the water on the prop actually seats the prop on the shaft. If this is your issue and you don't get it taken care of, you can damage the shafts eventually. In the future, make sure when the props are installed, they are lapped on. Good Luck.
I agree with Chris, lap the props. And check the keys, they get hung up and prevent the prop from seating. Check the "PropScan" web site. They have a great article on installing propellers under their "technical information" section. Capt. George