WEICHAI WP2.1C - 6.7 Black Exhaust; 6.8 Coolant Temperature Too High

Operation and Maintenance Manual for WP2.1C/WP3.9C Series Marine Diesel 
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(3) Clearance between piston and cylinde
r
liner too big, causing thudding noise (The
noise disappears after fuel delivery to the
cylinder being cut off for 3 to 5 seconds)
Check and repair. Replace piston and liner if necessary.
(4) Clearance between crankshaft and main
bearing too big, causing low heavy pounding
noise periodically.
Check and repair. Replace main bearing or thrust plate.
(5) Clearance between crankpin and bearing
too big, causing dull pounding noise.
Check and repair.
Replace connecting rod bearing.
(6) Clearance between piston pin an
d
connecting rod bushing too big, causing sharp
knocking noise.
Check and repair. Replace bushing.
(7) Valve clearance too big, causing
chattering noise.
Readjust valve clearance.
(8) Piston striking valve, causing clear metal
noise.
Readjust valve clearance and valve timing.
6.7 Black Exhaust
Possible Causes Suggested Remedies
(
1
)
En
g
ine overlo
a
ded. Reduce lo
a
d.
(2) Fuel delivery not even or too much.
Adjust injection pump and governor.
(3) Injection pressure too low, causing
poor spray characteristics.
Readjust nozzle opening pressure.
(4) Fuel injection timing too late.
Readjust injection timing.
(5) Air cleaner choked.
Clear away dust from cartridge or replace cartridge.
(6) Wrong grade of fuel or bad fuel. Drain tank and refill with proper fuel.
6.8 Coolant Temperature Too High
Possible Causes Suggested Remedies
(1) Cooling water flow reduction due to loose
V-belt.
Adjust belt tension or replace V-belt.
(2) Engine overloaded for a long period. Reduce load.
(3) Cooling water insufficient. Refill radiator.