Stihl MS 661 User Manual

10 MS 661, MS 661 C-M
3.3 Chain Lubrication
In the event of trouble with the
chain lubrication system, check and
rectify other sources of faults
before disassembling the oil pump.
.
Condition Cause Remedy
Chain receives no oil Oil inlet hole in guide bar is blocked Clean oil inlet hole
Intake hose or pickup body clogged
or intake hose ruptured
Fit new intake hose and pickup
body
Valve in oil tank blocked Clean or replace valve
Teeth on worm worn Install new worm
Oil pump damaged or worn Install new oil pump
Machine losing chain oil Oil pump damaged or worn Install new oil pump
Oil suction hose connection
damaged
Install new oil suction hose
Gasket between two halves of
crankcase faulty or crankcase
cracked
Install new gasket, inspect both
halves of crankcase and replace if
necessary
Oil pump delivers insufficient oil Oil pump damaged or worn Install new oil pump
Oil pump delivery rate set too low Adjust oil pump
Worm driver is loose Install new worm
Sealing ring between oil pump and
crankcase damaged
Replace the sealing ring

Stihl MS 661 Specifications

General

Displacement	91.1 cc
Chain Pitch	3/8"
Engine Power	5.4 kW
Fuel Capacity	825 ml
Chain Oil Capacity	360 ml
Guide Bar Lengths	90 cm