Engine - Stihl MS 440 Service Manual

4.6

Engine

Always check and, if necessary,
repair the following parts before
looking for faults on the engine:
Air filter
Fuel system
Carburetor
Ignition system
Condition
Engine does not start easily, stalls
at idle speed, but operates normally
at full throttle.
Engine does not deliver full power
or runs erratically
Engine overheating
MS 440, MS 440 C
Cause
Oil seals in crankcase damaged
Crankcase leaking or damaged
(cracks)
Leak in muffler
Piston rings worn or broken
Muffler / spark arresting screen
carbonized
Air filter insert soiled
Fuel / impulse hose severely kinked
or damaged
Decompression valve sticking
Insufficient cylinder cooling.
Air inlets in fan housing blocked or
cooling fins on cylinder very dirty
Remedy
Replace the oil seals
Seat or replace the crankcase
Seal / replace muffler
Replace piston rings
Clean muffler (inlet and exhaust
opening), replace spark arresting
screen
Replace air filter insert
Fit new hoses or position them free
from kinks
Replace the decompression valve
Thoroughly clean all cooling air
openings and the cylinder fins.
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