27MS 440, MS 440 C
– Remove the carburetor and
prepare for testing – b 6.2.1.
: Connect pressure hose of tester
1106 850 2905 to nipple (arrow)
on test flange.
VA
176RA014
: Close vent screw (1) on the
rubber bulb.
VA
146RA063
: Pump air into the crankcase with
rubber bulb until the gauge
(arrow) indicates a pressure of
0.5 bar (7.25 psi). If this pressure
remains constant for at least 20
seconds, the crankcase is
airtight.
VA
176RA015
– However, 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. Bubbles will appear if a
leak exists.
– After finishing the test, open the
vent screw and disconnect the
hose of tester 1106 850 2905.
– Continue with vacuum test –
b 6.2.3
Oil seals tend to fail when subjected
to a vacuum, i.e. the sealing lip lifts
away from the crankshaft during the
piston's induction stroke because
there is no internal counterpressure.
An additional test can be carried out
with the vacuum pump to detect this
kind of fault. Carry out the same
preparations as for the pressure test
– b 6.2.2
: Connect suction hose of vacuum
pump 0000 850 3501 to nipple
(arrow) of the test flange.
VA
176RA014
: Close the vent screw (1) on the
pump.
: Operate lever (2) until pressure
gauge (3) indicates a vacuum of
0.5 bar (7,25 psi).
VA
176RA018
3
1
2
6.2.2 Pressure Test 6.2.3 Vacuum Test
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