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S&S Swan Maintenance - Engine / gear problems
03 January 2021 - 17:45
#1
Join Date: 24 August 2015
Posts: 5

Engine / gear problems

My diesel engine (BH-Marine Kubota 29 HP) has developed a vibration and noise when in reverse. The loud beating noise and vibration noise comes and goes with varying throttle input. More throttle, more noise and vibration on reverse.

Stops almost if put back the throttle.  When putting the gear to neutral of forward the loud beating/vibration noise disappear. The gearbox has been changed and still these symptoms. Is it an engine problem/gear or could it be a problem with the prop (Pruntons H5)?  Any good suggestions?

Henrik

38/019

04 January 2021 - 09:50
#2
Join Date: 02 January 2008
Posts: 1461

Dear Henrik

It sounds like the propeller blades can hit the rudder skeg when in reverse.
This propeller is peculiar as the blades turn freely 360 degrees on the hub, and this requires sufficient free space around the propeller.
 
 If the boat is in the water, it would be advisable to lift it and check what is going on.
 If the propeller is loose on the shaft, it may have moved slightly aft, and this has changed the clearance to the skeg.
 
If the boat is out of the water you should turn the shaft so one blade is straight up, and then rotate it a full circle and see if it touches the skeg at any point.  Hit marks on the skeg can be expected.
 
It is possible that engine and shaft need to move forward slightly, but not too much, as then noise in forward gear may result.
 
Kind regards
Lars

17 January 2021 - 09:16
#3
Join Date: 24 August 2015
Posts: 5

Dear Lars,

 

Thank you for your message. "Unfortunately" the possible problem that you described seems not to be the case here. No traces regarding the moving of the shaft on the boat. It seems that this problem might be a gear or engine problem.

Byt the way, greethings from a good friend of mine to, Lica Feron.

Best,

 

Henrik

17 January 2021 - 15:27
#4
Join Date: 02 January 2008
Posts: 1461

Thank you for the greetings, the same to him

Lars

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