Vacuum Test; Pressure Test - Stihl FS 240 Service Manual

1
3
2 2
: Orient flange (1) 5910 850 4201
and push it onto the studs (2)
: Tightly screw on nuts (3)
5.2.2

Vacuum test

Oil seals tend to fail when subjected
to a vacuum. In other words, the
sealing lip lifts away from the
crankshaft during the piston's
induction stroke because there is no
internal counterpressure.
This kind of fault can be detected by
testing with pump 0000 850 1300.
4
1
2
: Push the hose (1) of pump
0000 850 1300 onto the
connector (arrow)
: Slide ring (2) to the left
– Vacuum test
FS 240 C, FS 260 C, FS 360 C, FS 410 C, FS 460 C-M
: Operate lever (3) until the
pressure gauge (4) indicates a
vacuum of 0.5 bar
If the vacuum reading remains
3
constant, or does not decrease by
more than 0.3 bar within 20
seconds, it may be assumed that
the oil seals are in good condition.
If the vacuum in the crankcase is
reduced further, the oil seals must
be replaced, b 5.3.
– After testing, slide the ring on the
pump back to the right to vent the
pump.
– Continue with pressure test,
b 5.2.3
5.2.3

Pressure test

The same preparatory steps are
required as for the vacuum test,
b 5.2.2.
3
: Slide 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
crankcase is airtight
– If the pressure drops, the leak
To find the leak, coat the suspect
area with soapy water and
pressurize the crankcase. Bubbles
will appear if a leak exists.
– After testing, slide the ring on the
– Remove flange 5910 850 4201
– Install the carburetor, b 11.3
– Remove muffler and remove
– Install gasket, cooling plate and
– Reassemble remaining parts in
3 2
1
must be located and the defective
part replaced
pump to the left to vent the pump
– disconnect the hose
on intake elbow
sealing plate 0000 855 8106
muffler, b 5.1
reverse order
27