Stihl 029, 039 - 4.7 Piston Rings

STIHL 029, 039 35
4.7 Piston Rings
Note: The snap ring must be fitted so
that the ring gap is on the piston's
vertical axis (it must point either up or
down).
- Heat the piston on an electric
heating plate to approx. 60°C
(140°F) and slip it over the con-
necting rod so that the mark (arrow)
on the piston head points towards
you - the long stub of the crankshaft
must be on the left.
- Push the assembly drift, small
diameter first, through the snap ring
already fitted, the piston bore and
the small end (needle cage). Line up
the piston.
- Fit the piston pin on the assembly
drift and slide it into the piston (the
piston pin slides home easily when
the piston is hot).
- Use the installing tool 5910 890
2210 to fit the snap ring in the
piston boss.
Note: The snap ring must be fitted
so that the ring gap is on the
piston's vertical axis (it must point
either up or down).
- Install the piston - see 4.5.
- Remove the piston from
the cylinder - see 4.5.
- Remove rings from piston.
- Use a piece of an old piston
ring to scrape the grooves
clean.
- Install the new piston rings in
the grooves so that the radii at
the ring gaps face upward.
- Install the piston - see 4.5.
Top:
Piston ring grooves
Bottom:
Fi
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in
g
p
i
sto
n rin
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Top:
Installing the piston pin
Bottom:
Insetting snap ring with installing
tool 5910 890 2210
1 = Mark (arrow)
2 = Long crankshaft stub