Cylinder Leak Down Tester Installation - Stihl 5910 890 1700 Technical Information

BR 500, BR 550, BR 600
Flywheel blocking tool installed.
The cylinder leak down tester is capable of
verifying cylinder leakage in all 2-stroke and 4-
stroke cycle engines. The hose on the tester
has a 14 mm diameter thread for conventional
spark plugs and and an adapter is included for
use in engines that utilize a 10 mm diameter
spark plug thread.

Cylinder Leak Down Tester Installation

To install the tester, thread the adapter hose
into the spark plug opening. Before connecting
the gauge assembly to the adapter hose, turn
the pressure regulator knob counterclockwise
until there is no tension on the regulator knob
(damage to pressure gauge can occur if the
regulator is not backed off before connecting
to air compressor).
Connect an air source of 90 PSI minimum to
the air inlet on the pressure regulator. Turn the
regulator clockwise until the needle on the left
gauge reaches the red set point at the 12
o'clock position, the needle on the right gauge
DLR 2007-02 New Special Tools ea 2012.doc
should now read zero. If not, adjust the
regulator until the right gauge is set to zero.
The gauge assembly is now ready to be
connected to the spark plug adapter hose.
Above view of the tester showing cylinder
leakage of 75%.
The recommended leakage should not
exceed 10%. If so, the component at fault
will need to be determined (exhaust valve,
intake valve, piston rings, scored piston).
This can be determined by listening for any
escaping air at the intake port, exhaust port
or pushrod openings in cylinder head.
If the exhaust valve is leaking, STIHL
recommends using STIHL Engine De-
Carbonizer fluid (part no. 0781 313 8019)
before disassembling the engine.
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