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Problem: Vibrations
Possible Cause Solution
Poor alignment to shaft: The alignment must be accurate even if a flexible
coupling is used (see section 1, Alignment).
Flexible mounts not adjusted correctly to take even weight: Check relative compression of each mount.
Flexible mount rubber perished: Replace. (Diesel or oil will eventually perish
most rubbers.)
Loose securing nut on flexible mount: Check alignment and then tighten the nuts.
Insufficient clearance between the propeller There must be at least 10% of the propeller
tip and the bottom of the boat: diameter as tip clearance between the propeller and
the bottom of the boat. Reduce propeller diameter /
increase pitch.
Loose zinc anode on the shaft: Tighten or replace.
Worn cutless bearing or shaft: Replace.
Weak engine support / bearers: Check for cracked or broken feet.
Problem: Knocking noise
Possible Cause Solution
Propshaft touching gearbox output coupling Adjust, giving correct clearance give 5mm - 10mm
through split boss or Type 16 coupling: between gearbox and propeller shaft
Flexible mount stud touching engine bed: Adjust stud to clear
Drive plate broken: Replace / repair
Engine touching engine bed: Re-align engine / modify bed
Injectors blocked through excess carbon Remove and check injector nozzles, replace
caused by water in the fuel: if required.
1640_Aug_2013.qxd:beta 1660 manual 18/11/13 10:48 Page 47
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