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lA MARINE ENGINES-W.4
exchanger) cooling also incorporate a water pump
of the centrifugal variety.
Ceotrüugal Type Water Pump.
Since the centrifugal type water pump employed
on those Marine engines incorporating indirect
(heat exchanger) cooling systems is identica!
with that pump titted to L4 engines in genera!.
maintenance instructions for this type of pump
may be obtained by referring to Section Q.
Rubber Impeller Type.
This type of pump is gear driven inasmuch as a
gear wheel attached to the impeller driving shaft
is in constant mesh with the engine camshaft gear
whee!. the pump itse!f being !ocated on the star-
board side of the engine directly below the
dynamo.
".
When replacing the cam fitted in the impeller
housing. be certain to treat the entire top surface.
rear face and securing setscrew hole with a suit-
able jointing compound. NOTE : This cam will go
into place one war only.
With the assem bied pump fitted to the engine.
backlash between the pump and I:amshaft gears
should be .003 in. to .009 in. (.08 to .23 mm). To
achieve this in production. two joints may have
been fitted between the pump gear wheel housing
and the ~ngine timing case. Should this be SQ.
ensure that both joints (or two new joints) are
replaced when refitting the pump.
ti the engine is to be withdrawn from service
for any length of time it will be necessary to
effect lubrication of the rubber impeller at the
commencement of the storage period. Tbis may
be achieved by removing the end cover (Item 1.
Fig. W.2) and placing glycerine between the vanes
if the impeller (Item 2. Fig. W.2).
Exhaust Manifold.
The exhaust manifold is water cooled and
constructed of cast iron. An air release cock is
provided at the forward end of the manifold
jacket. whereby any air present in th~ water
cooling system may be removed.
OU Cooler.
Provision is made at the front end of tl.e sump
for the fitment of an engine lubricating oir cooler.
With this, heat from the engine oir is lost as it
circulates round a system of tubes through which
are pumped water from the cooling system.
With the fitting of a hydraulic gearbox, a
further similar type oir c;ooler must be titted in
order to cool the gearbox oir. tThe mounting for
this additional cooler is on the top of the gearbox.
The pump necessary to lift the oil is ~nclosed in
the gearbox-
Sump Oir Pump (Hand Operated).
On the majority of marine installations it is
impossible to gain access to the sump drain plug
which is situated on the bottom of the sump.
Therefore, in order to facilitate the draining ot
the engine oil. a hand pump may be provided
This pump when used must be titted ~'emote from
the engine. Drainage of the sump is etfected by
operation of the pump af ter attachir:g a leng th of
suitable piping to the inlet side of the pump and
placing the free end of the pipe into the SIImp via
the dipstick orifice.
Removal aod Dismaotling.
First dis~onnect water inlet and outlet hoge
connections. The pump may then be detached by
removing the setscrews that secure it to the engine
timing case.
To dismantie the pump, proceed as follows :-
Remove rear end cover.
Remove impeller.
Remove wearplate.
W ith the front bearing cover removed. a suitable
press may be used to press out the impeller shaft
together with the front bearing, leaving the driving
gear wheelloose in its housing.
The cam in the impeller housing maf then he
detached by removing the single securing setscrew.
Remove rubber seal in impeller housing.
Remove rubber
..
0
,.
ring.
Remove distance-pieces.
The driving gear wheel housing and impeller
shaft rear hearing may then be removed from the
pump body.
Finally remove front rubber seal.
To reassemble the water pump, the reverse
order of the above procedure should be adopted,
care being taken 'when replacing
the rubber
impeller that the blades alllay
in the same direc-
tion relative tv the rotation of the pump. i.e.
blades trailing.
When reassembling, ensure that the rubber
impeller is coated with a layer of water resisting
grease. It should also be noted that, if necessary,
the impeller may be dismantled without removing
the water pump.
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