Polaris RANGER 1000 2020 Service Manual page 246

ENGINE / COOLING / EXHAUST
3. Turn the engine over by hand until the piston in that
cylinder is at top dead center (TDC).
NOTICE
If engine is not at TDC when air pressure applied to the
cylinder, the engine will likely turn over. Keeping the
piston at TDC vertically aligns the piston and
connecting rod with the crank
Leaving the remaining spark plugs installed will help
provide some additional resistance to the engine
unintentionally turning over.
Remove any tools used to turn the engine over before
putting air to the cylinder. If the cylinder being tested is
not perfectly on TDC, the engine will likely turn over
quickly and tools can strike you or damage the
machine.
4. Install the gauge's air-fitting adapter into the spark
plug hole and connect air pressure to the inlet side of
the gauge. Remember to double-check that your
gauge reads "zero" before you start.
5. Gradually increase air pressure up to no more than
100 psi. Ensure piston remains at TDC. If engine
turns over, reduce supplied pressure to 0 and rotate
engine to TDC.
6. Record your leak-down percentage for the cylinder
you're testing. Test any remaining cylinders using the
same method.
IMPORTANT
Refer to the manufacturers instructions to calculate the
leak. Some testers may not use a calculation and the
gauge may give you a percent of leak or capacity.
NOTICE
If the same cylinder is tested multiple times without
running the engine can cause variable readings.
Cylinder Leakage Service Limit:
If leakage exceeds service limit, inspect the engine for
the cause.
TROUBLESHOOTING
Test and compare all cylinders before attempting further
repairs. Leak percentage should be consistent between
cylinders. A 5 to 10 percent variance between cylinders
would likely be considered normal.
3.94
CAUTION
20%
No engine will have a perfect seal with 0 percent loss. A
leakdown reading of less than 10 percent loss indicates
the engine is in good condition. When performing the test
monitor where the leakage is occurring. At 20 percent,
suspect an internal issue, and an overhaul is likely.
Common leak areas:
• Cylinder Head Gasket
• Piston / Piston Rings / Cylinder Wall
• Intake Valve(s)
• Exhaust Valve(s)
• Valve Seat(s)
Pay close attention during testing air that can be heard or
felt is the best indication of where the leak is originating.
Symptom
Air can be heard / felt
through the intake or
exhaust
Air can be heard / felt
through the oil fillcap or
dipstick area
Bubbles seen / heard in
the cooling system
9850045 R01 - 2020-2021 RANGER 1000 Service Manual
Cause
Suspect a valve sealing
issue
Air is escaping past piston
and / or rings. Inspect ring
lands, rings, piston and
cylinder
This indicates that the
cooling system is
pressurizing, suspect a
cylinder head or head
gasket issue
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