2006 Johnson SD 30 HP 4 Stroke Outboards Service Manual, PN 5006592, Page 119Get this manual
POWERHEAD TEST PROCEDURES
TEST PROCEDURES
Cylinder Compression Test
Start the engineAllow the engine to warm up, then shut off the engineRemove the engine side coversRemove all spark plugsInstall compression gauge and adapter into the plug hole
WARNING
Disconnect the safety lanyard from the emergency stop switch prior to cranking the engineThis will prevent any residual fuel from the cylinders from being ignited by spark from the spark plug capWhile cranking the engine, note the maximum pressure reading on the gauge for each cylinder
IMPORTANT: The values that are shown are
only guidelines, not absolute service limitsCylinder Compression Test