Paragon hydraulic transmission noise

[bongo]

Our sailboat’s auxiliary Diesel engine, a Westerbeke 40/108, (sharing many parts with a Perkins 4-108), is dripping lube oil from the rear crankcase seal. I’m commencing on changing that seal. To do this job I have to remove the Walter V-drive and the Paragon P21-ML hydraulic planetary transmission. Our propeller is a Kiwi-prop.
The transmission has never had any problems or leaked any transmission fluid. My question is, since I’m removing it for the seal job, is: When operating in the ahead direction it is very quiet. But, when operating astern, it is, and has always been quite loud, (not bad from the helm, but loud in the engine compartment. In addition, the propeller shaft slowly turns, (approx. 3 rpm in the ahead direction), when the tranny is in neutral.Is this normal? Or is this indicative of issues that should be addressed while I have it out?

Thanks in advance, Greg

[DougR]

Paragon transmissions use a planetary gear mechanism to develop reverse rotation. When the gear box is in forward mode, the clutch and planetary assembly rotate as one unit and there’s is no noise. When you shift to reverse the reverse brake band clamps on the outside of the planetary assembly, causing the planet gears to revolve around and rotate the sun gear in the opposite direction, giving you reverse gear. This gear motion of the planetary gears causes the noise that you hear when in reverse gear.


If the prop shaft slowly rotates when in neutral it could be something as simple as oil drag on the clutch plates, and that’s nothing to worry about, especially if it has done it since new. Make sure you are using the correct oil, as oil that is too heavy can cause this drag.

If the rotation is more recent, or is very strong ( you can’t stop the rotation by lying your hand lightly on the shaft) it’s possible that there are some warped clutch plates, or the clutch plate separation spring has failed, and you might want to have that looked at.

[Midnight Son]

Woah, use slip-joint pliers NOT your hand. Don't want exceedingly serious injury/death. Slight pressure, top jaw on rotation towards the person checking, ready to drop.
Cheers

[bongo]

Thanks for the info. I have a very strong mechanical background, but even so differentials and planetary gears are PFM. I use an automatic transmission fluid. I researched it, don’t remember which one, but it is in my records aboard. I found that the damper between the flywheel and tranny was about to fail, so I’m replacing it too. Also doing all four engine mounts. Hopefully I never have to do this job again. No wonder people with means just re-power.