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S&S Swan Maintenance - Prop shaft sealant, 38
06 December 2013 - 16:02
#1
Join Date: 31 January 2007
Posts: 46

Prop shaft sealant, 38

Greetings all,

I purchased a new engine for Swante about a year ago - a Yanmar 3JH5E. The work was done in Gran Canaria. I sailed up to Lagos, Portugal this spring and back to GC in September. The engine now has about 230 hrs. On my return I noticed that the prop shaft enters the white plastic sealant at an angle, and this situation has gotten worse, to the point that there is now no clearance at all at the bottom (between the white plastic and the shaft), and plenty clearance at the top. Also, the rubber hose that makes up part of the sealing has been torn. There is no leak when the boat is not moving. (I will try to enclose a picture when the taxt is finished.)

Has anyone else experienced this problem and what did you need to change in order to resolve it? Any advice will be gretly appreciated.

Seasonal greetings to all,

Terje

07 December 2013 - 18:23
#2
Join Date: 02 January 2008
Posts: 1547

Dear Terje
It sounds like you have a shaft alignment problem. Disconnect the propeller shaft flange from the reduction gear flange. Lift the shaft forward end until a stop is felt when it touches the stern tube upper edge, drop the shaft until it stops at the stern tube lower edge, and finally support the shaft in a position halfway between these stops. This is the normal operating position.
Is the shaft seal now better aligned? The flexible hose needs to be replaced if damaged.
If the engine is not perfectly lined up with the shaft - i.e. there is now a height or angular difference between the two flanges, or both - the engine needs to be aligned. You can do this yourself as follows:
First lift one end of the engine slightly so the load comes off the flexible mounts, lower it slowly making adjustments so the mounts each side begin to take load at the same time. This is for eliminating diagonal engine support which can cause strange vibration problems.
Then adjust the engine mount heights as required, taking care to use an equal number of turns on both mounts at one end, then move to the other end of the engine, and adjust both mounts some other equal number of turns. Continue adjusting each end until the flanges fit perfectly together. The recommended maximum gap at any point is 0.012 mm per inch flange diameter when the flanges on the opposite side touch.
Kind regards
Lars

08 December 2013 - 14:41
#3
Join Date: 31 January 2007
Posts: 46

Dear Lars,

Once again, you help solve the problem - thank you!

I gather from your answer, that I probably will not have to change any of the parts in the sealing - other than the torn rubber hose. Do you have the dimensions/specification of that item?

Thanks again for good help in 2013 and all the best for 2014!

Kind regards,

Terje.

08 December 2013 - 19:34
#4
Join Date: 02 January 2008
Posts: 1547

Dear Terje
I do not have the hose specs, but it needs to be heavy duty - it keeps the water out.
Appears the shaft alignment was far off, and you will see if the seal leaks or not.
Kind regards
Lars

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