VIBRATION on Test Run on the Hard Before Launch

[Bob Ohler]

I have a CD30 with the Universal M18 engine with a Hurth transmission.

I did a test start prior to launch today. I supplied water to the engine with a hose filling a bucket. The engine started right up. However, I thought I would engage the transmission as a test as well.

In forward, it initially seemed fine. However, when I put it into reverse, I heard a loud vibration noise. I have also experienced this before, but when the boat was in the water. I stopped the engine and opened up the packing nut. The packing is only 3 to 5 years old. Without removing the packing, the packing appeared to be in good shape. I decided to add a little grease inside the packing cup, and a smear on the mating surface. I also topped off the transmission fluid. On restart, I thought that I had solved the problem, but the noise and vibration came back, mostly in reverse. I then loosened the packing nut, and then re-tightened it, but only hand tight. The first time I tightened the packing nut, I went hand tight, plus an 1/8 of a turn. Still the vibration in reverse persists.

Are my problems a result of putting the prop in gear while the boat is out of the water, or am I looking at a transmission job? The cutless bearing appears to have very little play.

I was not experiencing this vibration last fall, prior to haul out.

Should I just wait and try it again on launch day, later this week? I can always repack the packing nut after the boat is launched.

Thanks,

Bob O.

[Frenchy]

Hi Bob, How about unscrewing the packing nut completely and taping it to the shaft, squirting some soapy water up into
the cutless bearing and then starting the engine, running in forward and reverse. If the vibration and noise disappears, it's either
the dry cutless bearing or something isn't right with the stuffing box.
If you still have vibration, it might be bad engine mounts, a bent prop shaft, a misaligned engine or possibly the transmission.
Worn or broken engine mounts are common. My Universal 5424 had two broken engine mounts when I purchased the boat.
The threaded shafts looked like they were intact, but under power you could see the upper part of the thread bouncing around
and the lower part static.
You can test for broken mounts with a crow bar, lifting up on the engine near the suspect mount. For some reason,
a common one to break on a R.H. propeller is the starboard rear. Good luck- let us know if you find anything. - Jean

[Dean Abramson]

I personally wouldn't put my boat in gear while running it on the hard (which I have done several times in neutral).

Maybe dry packing is causing the vibration?? I would think that the boat would have to be in the water for a while to get the packing soaked right. I'm not sure that squirting water into the cutless bearing would get the job done.

Caveat, though: I'm not your most mechanical guy. I could be way off on this.

I have gotten an unfriendly noise when I've tried to go from forward to reverse too quickly (also a great way to kill the engine at an inopportune moment), but not a vibration.

[mgphl52]

I pretty much agree with the "no forward/reverse" while on the hard. The cutlass is designed to allow water into the bushing. Without that flow, you may have issues.

[Maine Sail]

How were you lubricating the water lubed cutlass bearing? Dry rubber on a dry shaft = not good....

[Bob Ohler]

Lesson learned... It's OK to start the engine on the hard (with an adequate supply of cooling water). It is not OK to put the transmission into gear.

Once she was lowered into the water, the noise never presented itself again.

Thanks for the sound advice and learning along with me.

Fair winds,

Bob

[Dean Abramson]

Good news!