Yanmar 3YM30, Sevice Manual

Page: 47 / 224

2. Inspection and adjustment
32
(3) Replace the marine gear lube oil.
Refer to 2.2.2(3) for the procedure.
(4) Replace the engine lube oil filter.
Refer to 2.2.2(2) for the procedure.
(5) Check the impeller of the cooling water
pump (seawater pump).
1) Remove the seawater pump cover and take out
the O-ring, impeller and wear plate.
2) Inspect the rubber impeller, checking for splitting
around the outside, damage or cracks, and replace
if necessary.
Depending on the use, the inside parts of a
seawater pump may deteriorate and the discharge
performance may drop. At the specified interval or
when the discharge volume of seawater is
reduced, inspect the seawater pump in
accordance with the following procedures.
a) Loosen the seawater pump cover set bolts and
remove the cover.
b) Illuminate the inside of the seawater pump with a
flashlight and inspect.
c) If no damage is found, reassemble the cover.
d) If any of the following problems are found, take out the O-ring and impeller. If necessary, replace
with new one and reassemble the cover.
• Impeller blades are cracked or nicked. Edges or surfaces of the blades are marred or scratched.
Note: The impeller must be replaced periodically (every 1000 hrs or four years whichever comes first).
e) If a large amount of water leaks continuously from the water drain pipe beneath the seawater
pump during engine operation, check the oil seal inside the seawater pump.
[Notice]
The seawater pump turns in the counterclockwise direction, but the impeller must be installed by
turning in the clockwise direction. If the impeller has been removed for any reason and must be
reassembled, be very careful not to make a mistake and turn it in the wrong direction. Additionally, if
the engine is being turned manually, be careful to turn it in the correct direction. Incorrect turning will
twist the impeller blades and damage it.
Pump body
Impeller
O-ring
Cover
(Seawater pump)
Seawater pump Impeller
Direction of impeller
Impeller rotating
direction