15Series 4144 Powerhead
6.1.3 Pressure Test
Carry out the same preparations as 
for the vacuum test, b 6.1.2
– Always carry out the vacuum test,
before the pressure test, b 6.1.2
: Connect pressure hose (1) of 
pump 0000 850 1300 to nipple 
(arrow).
: Push ring (1) to the right.
: Operate the lever (2) until the 
pressure gauge (arrow) indicates 
a pressure of 0.5 bar. If this 
pressure remains constant for at 
least 20 seconds, the engine is 
airtight.
– If the pressure drops below 0.5 
bar within 20 seconds, the leak 
must be located and the faulty 
part replaced.
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To find the leak, coat the suspect 
area with oil and pressurize the 
engine. 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 test flange.
– Install the carburetor 
– see service manual for 
"Series 4144 Components – FS, 
FC, KM"
– Loosen the muffler and pull out 
the sealing plate.
– Tighten down the muffler firmly.
– Reassemble all other parts in the 
reverse sequence.
– Tightening torques, b 3.3
6.2 Oil seals
It is not necessary to disassemble 
the engine to replace the oil seals.
Ignition side
– Remove the engine – see service 
manual for "Series 4144 
Components – FS, FC, KM"
– Remove the flywheel, b 7.5
– Free off the oil seal in its seat by 
tapping it with a suitable tube or a 
punch.
: Apply puller (1) 5910 890 4400 
with No. 3.1 jaws 0000 893 3706.
– Clamp the puller arms.
– Pull out the oil seal.
Take care not to damage the 
crankshaft stub.
– Clean the sealing face, b 9
– Lubricate sealing lips of new oil 
seal with grease, b 9
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