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COMPRESSION CHECK (described for 6 cylinder engines)
- Buy an
automotive style compression tester from an auto parts store.
- Run the engine
for a minute or two so it is slightly warm and has oil throughout
- Remove all 6
wires from the coils (Be gentle with the locking clips)
- Remove all six
coils by loosening bolts until coil pulls off the spark plug
- Remove spark
plugs with 5/8 sparkplug socket. Hold tool straight to prevent
braking the plug
- Screw
compression tester into one cylinder until seated against the O-ring
on tester
- Open the
throttle fully
- Stay clear of
the propeller and tie the airplane down
- Provide power to
the starter switch but leave the ignition off.
- Press the start
switch and watch the needle on the compression tool. It will
stabilize after a few seconds of cranking and not increase any
more. Write down this reading. It will be somewhere between 180
and 230 psi.
- Repeat the test
on the rest of the cylinders (Be sure to reset the tool by pressing
the button and release previous pressure)
- Below 180 -
clean engine with marvel mystery oil in the gas / use auto fuel only
for a while
- 180 to 190 is
good
- 190 to 210 is
great
- 210 to 230 can't
get better and be sure to use good quality fuel
- Reinstall spark
plugs with a small amount of anti seize on the second and third
thread of the plug (stay away from the electrode)
- Tighten new
plugs until the built-in crush washer is compressed. You can feel
it compressing.
- Tighten older
plugs (washer already compressed, until snug against the block, then
1/8 turn)
- Reinstall cols
- Reinstall coil
wires
- Close the
throttle
Record results in the engine logbook. |