Hamilton Jet HJ241 Manual page 80

7 FAULT FINDING
7.1 J U F
ET NIT AULTS
NO
POSSIBLE CAUSE
5 Excessive high pitched rattling, or rattling whine coming from the Jet Unit.
Blockage of the Jet Unit.
Faulty Thrust Bearing.
Cavitation is occurring.
6 Bad vibrations.
Blockage of the Jet Unit.
Worn Marine Bearing, or Marine
Bearing water drain hole in the Tail-
pipe blocked.
Something caught in the Impeller.
Worn driveshaft universal joints.
7 Engine revolutions gradually increasing over a period of time. Take off performance poor.
Worn or blunt Impellers.
Excessive Impeller tip clearance.
8 Sudden increase in engine revolutions with no noticeable decrease in thrust.
Air ingestion, or cavitation.
Faulty tachometer.
9 Excessive engine revolutions, noisy Jet Unit and aerated water from Nozzle.
Screen blocked with wood or debris
or rope through Screen and wrapped
around shaft.
Object jammed in Stators and / or
Impeller.
7.2
Table 5: Jet Unit Faults
SYMPTOMS
SOLUTION
The Blockage must be removed.
Inspect and repair the Thrust Bearing.
Blocked Intake Screen.
Check for Blunt or damaged Impeller.
Excessive Impeller tip clearance.
Wrong type of Impeller fitted.
Vessel overloaded.
Weight too far aft.
Bad weather or sea conditions.
Poor installation of Jet Unit into vessel.
The blockage must be removed
Check and clear the water drain hole in the
Tailpipe Cone, inspect and repair the
Marine Bearing.
Check through Inspection Hatch, clear
obstruction.
Inspect and repair the driveshaft as per
manufacturer's recommendations.
Inspect and repair the Impeller as well as
the Wear Ring.
Inspect and repair the Impeller as well as
the Wear Ring.
See No.5 above.
Repair tachometer.
Remove blockage.
Remove object.
HJ-241 / HSRX
REFER
Sect. 2.9
Sect. 9.6
Sect. 2.8
Sect. 2.9
Sect. 9.7.6
Sect. 9.5.2
Refer Draw-
ing HJ-241-
03-001
Impellers
Sect. 5
Sect. 2.9.3
Sect. 9.7.1
Sect. 8.5.1/1
Refer to
Manufactur-
ers Manu-
als.
Sect. 8.5.1/
17a) &
17b).
Sect. 9.7
Sect. 8.5.1/1
& Sect. 2.9