Operation and Maintenance Manual for WP2.1C/WP3.9C Series Marine Diesel
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(4) Cooling water flow reduction due to lo
water pump efficiency.
Check clearance between water pump impeller and housing.
Replace impeller if necessary.
(5) Defective water pump impeller. Replace impeller.
(6) Cooling water circulation obstructed. Clean cooling system.
(7) Defective thermostat. Replace thermostat.
(8) Defective water thermometer. Replace thermometer.
(9) Insufficient lubrication. Inspect lubricating system and clean oil gallery.
6.9 Low Lubricating Oil Pressure
Possible Causes Suggested Remedies
(1) Insufficient oil in oil sump.
Check oil level.
Refill to the specified level.
(2) Defective low oil pressure alarm. Replace alarm.
(3) Clogged oil gallery. Clean oil gallery and blow away dirt with compressed air.
(4) Clogged oil strainer. Dismount oil strainer. Clean it in kerosene.
(5) Clogged oil filter and defective by-pass
valve.
Replace oil filter cartridge. Readjust by-pass valve i
necessary.
(6) Excessive bearing clearances due to wea
of main bearing and crankpin bearing.
Repair or replace bearings.
(7) Engine overheated, causing high
temperature and low viscosity of lubricating
oil.
Reduce load to lower oil temperature or refill with suitable
oil.
(8) Too big clearance between oil pump
rotors and housing cover.
Replace rotors or housing cover of oil pump.
6.10 Excessive Oil Consumption
Possible Causes Suggested Remedies
(1) Worn piston ring or oil scraper ring
stuck in ring groove due to carbon deposits.
Wash oil scraper ring in kerosene or replace defective ring.
(2) Oil return holes plugged due to carbo
deposits.
Clean oil return holes in piston.
(3) Oil level too high. Oil into the
combustion chamber.
Check with dipstick and drain oil to correct level.
(4) Leakage in lubricating system. Tighten connectors and replace sealing washers and gaskets.
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