Pressure Test; Oil Seals - Stihl FS 94 Instruction Manual

2 4
1
: Connect hose (1) of pump
0000 850 1300 to the nipple
(arrow).
: Push ring (2) to the left
– vacuum test.
: Operate the lever (3) until the
pressure gauge (4) indicates a
vacuum of 0.5 bar.
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.
If the pressure continues to rise
(reduced vacuum in engine), the oil
seals must be replaced, b 5.3.
– After finishing the test, push the
ring to the right to vent the pump.
– Continue with pressure test,
b 5.2.3
22
5.2.3

Pressure Test

3
Carry out the same preparations as
for the vacuum test, b 5.2.2
1
: Push ring (1) to the right
– pressure test.
: Operate the lever (2) until the
pressure gauge (3) indicates a
pressure of 0.5 bar. If this
pressure remains constant for at
least 20 seconds, the engine is
airtight.
– If the pressure drops, the leak
must be located and the faulty
part replaced.
To find the leak, coat the suspect
area with soapy water and
pressurize the engine again.
Bubbles will appear if a leak exists.
– After finishing the test, push the
ring to the left to vent the pump –
disconnect the hose.
– Remove the flange
5910 850 4200 from the intake
manifold.
– Install the carburetor, b 10.3
– Remove the muffler and the
sealing plate 0000 855 8106.
– Install the gasket, heat shield and
muffler, b 5.1
– Reassemble all other parts in the
reverse sequence.
3 2
5.3
When replacing oil seals, note that
the 12x22x5 oil seal (1) must be
installed at the ignition side and the
10x20x4 oil seal (2) at the starter
side.
It is not necessary to disassemble
the engine to replace the oil seals.

Oil Seals

1 2
Series 4149 Powerhead