XJ-S V12-5.3L (1982)
Compression Check: Testing and Inspection
Run the engine until it reaches its normal operating temperature.
Disconnect the spark plug leads from the spark plugs.
CAUTION:Before removing spark plugs, thoroughly inspect the area surrounding each plug for debris that may fall into the spark plug hole once the
plug is removed. Carefully use compressed air to remove debris.
Remove ALL the spark plugs.
Fit a compression test gauge to No.1 plug hole (RH bank).
NOTE: Cylinders are numbered from the front of the engine.
Turn the ignition key to position 3 (start) and crank the engine over with the starter motor for 10 seconds.
NOTE: The cranking speed must not drop below 300 rpm and the throttle must be wide open.
Make a note of the test gauge reading.
Remove the compression gauge and release the pressure from the gauge.
Repeat the procedure for the remaining eleven cylinders.
Check the spark plug gaps and refit the plugs.
Refit the plug leads.
Compression Pressure ...................................................................................................................................................................................... 200-220 psi
Differential between cylinders ....................................................................................................................................................................... 10 psi (max)
Firing order ................................................................................................................................................... 1A-6B-5A-2B-3A-4B-6A-1B-2A-5B-4A-3B
A= RH bank; B = LH bank.
Cylinders are numbered from the front of the engine.
Spark plug gap ........................................................................................................................................................................................................ O.025in
Spark plug to cylinder head .............................................................................................................................................................................. 9.5-12 Nm
