Vacuum Test - Stihl 034 Series User Manual

5.6.3

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.
An additional test can be carried out
with vacuum pump 0000 850 3501
to detect this kind of fault.
1
Connect suction hose of vacuum
pump 0000 850 3501 (1) to nipple
of test flange (2).
3
1
Close the vent screw (1) on the
pump.
Operate lever (2) until pressure
gauge (3) indicates a vacuum of
0.5 bar.
034, 036, 036 QS
Note:
If the vacuum reading remains
constant, or rises to no more than
0.3 bar within 20 seconds, it can be
assumed that the oil seals are in
good condition. However, if the
pressure continues to rise (reduced
vacuum in the crankcase), the oil
seals must be replaced, even if no
leaks were detected in the pressure
test.
– After finishing the test,
reassemble all parts in the
reverse sequence.
Note:
Coat the mounting screws for the
upper and lower muffler casings
with LOCTITE. Insert and tighten
down the screws (see "Tightening
Torques").
2
2
5.7 Replacing the Oil Seals
It is not necessary to disassemble
the complete crankcase to replace
the oil seals.
– Remove the flywheel -
– Remove the Woodruff key from
the crankshaft stub.
On machines with handle or
carburetor heating system, take
out the generator mounting
screws, lift the generator away
and put it to one side.
– Remove the clutch - see
– Remove the brake band -
4.4.1 and 4.5.1.
– Remove the oil pump -
– Fit No. 3.1 jaws 000 893 3706 in
the universal oil seal puller
5910 890 4400.
see 6.4.1.
4.3.
see
see 11.4.
33