Leakage Test - Stihl MS 440 Service Manual

: Examine the reflector foil (arrow)
and replace it if necessary –
b 6.7.2
2
3
: Fit the heat shield (1) in position.
: Position a new gasket (2) with the
bead (3) facing outwards.
– Coat the screw threads with
Loctite – b 16.
– Tighten down the screws – b 3.5
When assembling the parts, ensure
that size M6x20 screws are fitted at
the bottom and size M5x6 screws at
the top to secure the exhaust
casing.
MS 440, MS 440 C
1
Versions with catalytic converter
only
: Fit M6x30 screws (arrows) with
tensioning gear.
: Insert M5x30 screw (1) with
sleeve.
1
6.2

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 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.
25