Crankshaft - Stihl 4180 Series Manual

– Apply thin coating of sealant to
gaskets faces, b 12
: Tighten down the screws
(arrows) in crosswise pattern,
b 3.4
44
7.8.3

Crankshaft

Always check and, if necessary,
repair the fuel system, carburetor,
air filter and ignition system before
looking for faults on the engine,
b 4.1
– Remove the lower half of the
crankcase, b 7.8.2
3
: Lift the crankshaft (1) and pull the
piston out of the cylinder at the
same time.
– Pull off the oil seals (2 and 3).
– Inspect cylinder running face for
signs of damage and serious
scores. Install new cylinder if
necessary, b 7.10
3
1
: Examine ball bearings (1),
connecting rod (2) and gear (3).
– If one of these parts is damaged,
install a new crankshaft
assembly.
– Coat piston and piston rings with
oil.
2 1
– Fit piston rings so that their gaps
are offset 120 degrees.
– Use new oil seals.
– Lubricate sealing lips of oil seal
with grease, b 12
– Apply a thin coating of sealant to
the outside diameter of the oil
seal, b 12
– Fit oil seals over crankshaft with
their open sides facing inwards.
– Carefully fit piston in the cylinder.
– Install the crankshaft with new oil
seals.
– Fit lower half of crankcase,
b 7.8.2
– Install the flywheel, b 7.7
2
1
Series 4180 Powerhead