Vacuum Test; Pressure Test; Oil Seals; Ignition Side - Stihl MS 661 Manual

6.2.2

Vacuum Test

4
1
2
: 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.
However, if the pressure continues
to rise (reduced vacuum in the
engine),
the oil seals
must be replaced, b 6.3.
– After finishing the test, push the
ring to the right to vent the pump.
– Continue with pressure test,
b 6.2.3
6.2.3

Pressure Test

Carry out the same preparations as
for the vacuum test, b 6.2.2
26
3
: Connect hose of pump
0000 850 1300 to the nipple
(arrow).
: 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 crankcase
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 oil and pressurize the
crankcase 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.
– Loosen the muffler screws and
remove the sealing
plate 0000 855 8106.
– Replenish threadlocking
adhesive and install the muffler,
b 6.1
– Install the carburetor, b 13.4
– Reassemble all other parts in the
reverse sequence.
6.3
3 2
It is not necessary to disassemble
the engine to replace the oil seals.
6.3.1
– Remove the rewind starter,
1
b 9.2
– Remove the flywheel, b 7.7
– On machines with a heating
system, remove the screws and
put the generator to one side,
b 14.7
: Remove the key (1) from the
crankshaft stub.

Oil Seals

Ignition Side

MS 661, MS 661 C-M
1