Series 4180 Powerhead 7
3.5 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 Cause Remedy
Engine does not start easily, stalls
at idle speed, but operates normally
at full throttle
Low compression pressure Check compression with pressure loss or
compression tester, or check valve clear-
ance and readjust if necessary, remove
combustion residue
Oil seals in engine damaged Check for leaks and replace oil seals if
necessary
Engine pan is leaking Check for leaks and re-seal engine pan if
necessary
Gasket on spacer flange leaking Install new gasket
Valve lifter on cam gear defective Install new cam gear
Engine pan is damaged Replace engine pan
Engine does not deliver full power
or runs erratically
Air filter dirty Clean the air filter, replace if necessary
Gasket on spacer flange leaking Install new gasket
Cylinder or piston worn Install new cylinder or piston
Muffler / spark arresting screen carbonized Clean muffler (inlet and outlet), replace if
necessary, clean or replace spark arrest-
ing screen as necessary
Fuel hose blocked / kinked / damaged Check fuel hose and replace if necessary
Impulse hose or pump diaphragm dirty Clean impulse hose or pump diaphragm
Valve lifter on cam gear defective Install new cam gear
Engine overheating Insufficient cylinder cooling. Air inlets in fan
housing blocked or cylinder cooling fins
very dirty
Thoroughly clean all cooling air openings
and the cylinder fins
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