Engine; Exhaust Muffler; Leakage Test - Stihl 020 T Service Manual

4.

ENGINE

4.1

Exhaust Muffler

Troubleshooting chart - see 2.2.
• Remove sprocket cover –
see 3.1.
• Take out the screw (1).
• Remove the cover (2).
• Remove mounting screws from
underside of machine.
• Pull out the muffler.
• Remove the gasket.
STIHL 020 T
• Take out the screws.
• Lift lower casing away from
upper casing.
• Take out the screw.
• Remove baffle from guide in
upper casing.
• Clean baffle or fit a new one.
Note: If baffle is equipped with
spark arresting screen, make sure
the spark arresting screen is refitted.
Reassemble in the reverse
sequence.
Note: Install a new gasket.
Tighten screws of upper casing to
4 Nm (3 Ibf.ft) and muffler mounting
screws to 11.5 Nm (8.5 Ibf.ft).
4.2

Leakage Test

Defective oil seals and gaskets or
cracks in castings are the usual
causes of leaks. Such faults allow
supplementary air to enter the
engine and thus upset the fuel-air
mixture.
This makes adjustment of the
prescribed idle speed difficult, if
not impossible.
Moreover, the transition from idle
speed to part or full throttle is not
smooth.
The crankcase can be checked
thoroughly for leaks with the .
carburetor and crankcase tester
and the vacuum pump.
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