Engine - Stihl 4180 Series Service Manual

3.5

Engine

Always check and, if necessary, repair the following parts
before looking for faults on the engine:
Air Filter
–
Fuel 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
Series 4180 Powerhead
Cause
Low compression pressure
Oil seals in engine damaged
Engine pan is leaking
Gasket on spacer flange leaking
Valve lifter on cam gear defective
Engine pan is damaged
Air filter dirty
Gasket on spacer flange leaking
Cylinder or piston worn
Muffler / spark arresting screen carbonized Clean muffler (inlet and outlet), replace if
Fuel hose blocked / kinked / damaged
Impulse hose or pump diaphragm dirty
Valve lifter on cam gear defective
Insufficient cylinder cooling. Air inlets in fan
housing blocked or cylinder cooling fins
very dirty
Carburetor
–
Ignition system
–
Remedy
Check compression with pressure loss or
compression tester, or check valve clear-
ance and readjust if necessary, remove
combustion residue
Check for leaks and replace oil seals if
necessary
Check for leaks and re-seal engine pan if
necessary
Install new gasket
Install new cam gear
Replace engine pan
Clean the air filter, replace if necessary
Install new gasket
Install new cylinder or piston
necessary, clean or replace spark arrest-
ing screen as necessary
Check fuel hose and replace if necessary
Clean impulse hose or pump diaphragm
Install new cam gear
Thoroughly clean all cooling air openings
and the cylinder fins
7