Vacuum Test; Pressure Test - Stihl MS 441 Manual

8.2.2

Vacuum test

Oil seals tend to fail when subjected
to a vacuum, i.e. the sealing lip lifts
away from the crankshaft during the
piston's induction stroke because
there is no internal counterpressure.
Faults of this kind can be detected
with the aid of the pump
0000 850 1300.
1
: Connect suction hose (1) of
pump 0000 850 1300 to the
nipple (arrow).
1
: Slide ring (1) to the left.
: Actuate lever (2) until the
pressure gauge (arrow) indicates
a vacuum of 0.5 bar.
MS 441, MS 441 C
The oil seals are in good condition if
the indicated vacuum is maintained
or if the pressure rises to no more
than 0.3 bar within 20 seconds.
The oil seals must be replaced if the
pressure in the crankcase continues
to rise, b 8.3.
– When the test is complete, push
the pump ring to the right to vent
the system.
– Test at gauge pressure, b 8.2.3.
2
8.2.3

Pressure test

1
The preparations are the same as
for the vacuum test, b 8.2.2.
– Test under vacuum, b 8.2.2
before testing at gauge pressure.
: Slide pressure hose (1) of the
pump 0000 850 1300 over the
nipple (arrow).
41