View Full Version : Propeller shaft seperated from gearbox

03-15-2009, 11:04 PM
"I recently had my bellows replaced by a boatyard. While picking the boat up and moving it back to the slip I put it in reverse to slow the boat down. As soon as I did that the propeller shaft slid ack about 2" from the the gear box.

The boat is a 44' Jeanneau with a Kanzaki gearbox. I am writing to get your opinion if you think the work perfomred to the bellows could have contributed to this porblem. At this point I cannot even move my boat because the propeller shaft is not actually spinning regardless of which gear I have it in.

Is it possible for a propeller shaft to slide back because of something going wrong with the gearbox?

What actually holds the propeller shaft in place? I know it is keyed to prevent it from sliding out of the boat completely, but what it is keyed to?

One more thing, the reason we replaced the bellows was because it sprung a slow leak, it was not noticed until the water was turning the bilge on. As a result the gearbox did get water in it, it was since flushed out, but when it was put in reverse the gearbox lost all its oil.

Any insight or ideas would be appreciated. http://www.marineengine.com/discus/messages/12498/250361.jpgpic

03-16-2009, 12:09 AM
All it is is coincidental; what does the boatyard have to say about their work?

03-16-2009, 12:27 AM
"they gave me a quote to replace the gear box ($3,500). they were not able to provide a clear explanation what actually happened (which leaves me concerned). My first inclination is that the water in the gearbox contributed to the failure, but still does not explain how the shaft actually slid back. Since they replaced the bellows out of water, it seems like there is a possibility that something was not right. Unfortunatly I don't know enough about how the shaft connects to the motor well enough to diagnose it myself."

03-16-2009, 02:50 AM
"Hi, the boatyard is at fault. The transmission worked before they worked on it and not after. The propellor shaft is attached to the transmission with a flange. The key you talk about is there to prevent the shaft turning in the flange. There are several methods of keeping it from pulling OUT of the flange. This can happen. From the picture, the shaft did not pull out of the flange.
The yard needed to remove the flange from the propellor shaft to replace the bellows. Somehow they damaged the transmission. I have seen people using a slap hammer and other improper methods to seperate the shaft from the flange. This puts tremendous shock loading and strain on the transmission bearings and the nut holding the output shaft flange. The usual result is transmission failure. In this case, the transmission output shaft has backed out taking the seal along. What happened should be obvious when the transmission is opened up. You need a second opinion from a qualified marine technician.
Good luck."