RNLI Atlantic 85, Manual

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Activity 9 - Propulsion and Auxiliary Systems
B Class Atlantic 85 Manual – First Issue, June 2017
Activity 9 - Propulsion and Auxiliary Systems
Water pump
The water pump is on the top of the gearbox. It pumps the
raw/sea water up into the engine via a long tube. The pump
is made up of a rubber impeller that rotates eccentrically
inside a metal casing thus acting as a positive displacement
pump, forcing the water up into the powerhead.
The rubber impeller relies on the water to provide
lubrication and so it is vital that the engine is only run with
a form of water supply to the pump, be it with the lower
leg immersed in water or with a supply from water muffs.
An indication of the pump working satisfactorily is a flow
of water from the tell tale. If no water is present then
check that the suction points are not blocked (plastic bag
etc) and that the tell tale is not blocked before suspecting
a defective pump.
If the pump needs to be changed, refer to job card
0801-1Y-004 and 0801-1Y-005 (Staff level 2).
Output side
Input side
rubber bladed impeller
mounted eccentrically
within the pump casing
A typical ‘Jabsco’ type water pump
Changing the Impeller
1. Remove four bolts and their shaped washers from the
plastic cover. Slide cover and metal casing up input
shaft and place to one side.
2. Remove the collar above the impeller.
3. Remove the clamp and the three washers
underneath it.
4. Remove impeller by levering up from the bottom.
5. Remove the key with a hammer and chisel.
6. Remove bottom ported plate and gasket.
7. Inspect all items for damage, cracking, etc. Best
practice is to replace all items if possible.
8. Inspect water passages for blockages.
9. Refit in reverse order, apply gasket sealer and lightly
grease all metal components.
10. Apply a smear of grease to the inside of the metal
casing. Place casing inside cover ensuring correct
location.
11. Lower casing onto impeller, turning the input shaft
clockwise as you do so, to ensure blades are rotating in
the correct direction.
12. Using new bolts with washers correctly positioned,
tighten down bolts to correct torque setting to avoid
stressing the plastic cover.