Beta Marine Beta 14 Installation Manual page 68

Problem: Vibrations
Possible Cause
Poor alignment to shaft:
Flexible mounts not adjusted correctly to take even weight: Check relative compression of each mount.
Flexible mount rubber perished:
Loose securing nut on flexible mount:
Insufficient clearance between the propeller
tip and the bottom of the boat:
Loose zinc anode on the shaft:
Worn cutless bearing or shaft:
Weak engine support/bearers:
Problem: Knocking noise
Possible Cause
Propshaft touching gearbox output coupling
through split boss or Type 16 coupling:
Flexible mount stud touching engine bed:
Drive plate broken:
Engine touching engine bed:
Injectors blocked through excess carbon
caused by water in the fuel:
Problem: Transmission noise
Possible Cause
Check gearbox oil level:
"Singing" propeller:
Drive plate rattle at tickover:
Worn drive plate:
Propeller shaft hitting the Gearbox half coupling:
Propeller torsionals causing gears to rattle at low rpm:
Solution
The alignment must be accurate even if a flexible
coupling is used (please refer to 'Alignment' on page 31).
Replace. (Diesel or oil will eventually perish rubbers).
Check alignment and then tighten the nuts.
There must be at least 10% of the propeller diameter
as tip clearance between the propeller and the bottom
of the boat. Reduce propeller diameter/increase pitch.
Tighten or replace.
Replace.
Check for cracked or broken feet.
Solution
Adjust, giving correct clearance give 5mm - 10mm
between gearbox and propeller shaft.
Adjust stud to clear.
Replace/repair.
Re-align engine/modify bed.
Remove and check injector nozzles, replace if required.
Solution
Top up.
Check with propeller supplier about 'harmonics'.
Check engine rpm (must be 850rpm min. in gear).
Change.
Move shaft back to give 5mm - 10mm clearance
(Type 12/16 couplings only).
Fit a torsional flexible coupling such as Centaflex
type 16 or equivalent.
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