Stihl MS 661, Manual, Page: 36 / 138

35 MS 661, MS 661 C-M
Make sure the sleeves (arrows)
engage the holes and the gasket is
not pinched or twisted.
– Continue turning the service
tool's spindle until the gap
between the two halves of the
crankcase is closed.
– Remove the installing tool.
– Take out the M5x72 screws.
: Insert the screws (arrows) and
tighten them down firmly in a
crosswise pattern.
– Install the oil seals, b 6.3
– Fit the retaining ring at the clutch
side.
– Check and install the piston,
b 6.7
1166RA080 TG
1166RA071 TG
– Check and install the cylinder,
b 6.5
– Reassemble all other parts in the
reverse sequence.
6.6.1 Bearings / Crankcase
Each half of the crankcase can be
replaced separately if it is damaged.
Inspect and clean the sealing faces
on both halves of the crankcase
(including the cylinder sealing face)
– the sealing faces must not be
damaged in any way.
New crankcase halves are supplied
with the main parts preassembled
– see the parts list.
Parts not supplied with the new
crankcase must be transferred from
the original crankcase – check the
parts and replace if necessary.
If a new crankcase is installed, the
machine's serial number must be
stamped on it with 2.5 mm figure
stamps.
If the original crankcase is used
again, replace the oil seals and ball
bearings.
Examine both halves of the
crankcase for cracks. Clean all
sealing faces (remove any gasket
residue) and check them for
damage – all sealing faces must be
in good condition and clean.
– See also Troubleshooting,
b 3.7
– Remove the crankshaft, b 6.6
Ignition side of crankcase
: Use a punch to carefully drive out
the oil seal.
: Check and clean the crankcase
or replace if necessary.
– If this half of the crankcase is in
order, install a new ball bearing.
– Heat area of bearing seat to
about 160°C (320°F).
The bearing drops out as soon as
this temperature is reached.
1166RA085 TG