Engine - Stihl 029, 039 Service Manual

STIHL 029, 039
2.2

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
Cause
Oil seals between cylinder
and engine pan damaged
Manifold leaking
Engine pan leaking
Engine pan damaged (cracks)
Secondary air seepage through
poorly mounted or faulty
manifold
Piston rings leaking or
broken
Muffler carbonized
Insufficient cylinder
cooling. Air inlets in fan
housing blocked or cooling fins
on cylinder very dirty
Intake air preheating being
used at too high an outside
temperature
Remedy
Replace oil seals
Seal or replace manifold
Seal engine pan
Replace engine pan
Mount manifold correctly or
replace
Fit new piston rings
Clean muffler (inlet
and exhaust), replace spark
arresting screen (if fitted)
Thoroughly clean all cooling
air openings
Move shutter to
summer position
8