76
POWERHEAD
COMPRESSION TESTING
COMPRESSION TESTING
Start and run outboard until it achieves operating
temperature, then shut OFF.
Remove spark plug.
Advance throttle linkage to WOT.
Install compression tester’s hose attachment into
spark plug hole.
While starting the outboard with starter, note max-
imum pressure reading on gauge.
IMPORTANT: The values shown are guidelines
only, not absolute service limits.
If engine shows a variation in test, check for:
• Excessively worn cylinder wall
• Worn piston
• Worn or stuck piston ring
• Poor seating of valves
• Ruptured or damaged cylinder head gasket
Install all parts that were removed.
WARNING
Disconnect the safety lanyard from the
emergency stop switch prior to starting
the engine. This will prevent any residual
fuel from the cylinder from being ignited
by a spark from the spark plug cap.
Cylinder Compression Test
Standard
137 to 199 psi
(960 to 1400 kPa)
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