128
POWERHEAD
TEST PROCEDURES
TEST PROCEDURES
Compression Testing
Start and run outboard until it achieves operating
temperature, then shut OFF.
Remove spark plugs.
Advance throttle linkage to WOT.
Install compression tester’s hose attachment into
spark plug hole.
While cranking outboard with starter, note maxi-
mum pressure reading on gauge. Repeat proce-
dure for each cylinder.
IMPORTANT: The values shown are guidelines
only, not absolute service limits.
If engine shows a variation greater than 14 psi
(100 kPa) between cylinders, check for:
• Excessively worn cylinder wall
• Worn piston
• Worn or stuck piston rings
• Poor seating of valves
• Ruptured or damaged cylinder head gasket
Install all parts that were removed.
005554
WARNING
Disconnect the safety lanyard from the
emergency stop switch prior to cranking
the engine. This will prevent any residual
fuel from the cylinders from being ignited
by a spark from the spark plug cap.
Cylinder Compression Test
Standard
(models with decom-
pression system)
71 to 100 psi
(500 to 700 kPa)
Standard
(models without decom-
pression system)
142 to 185 psi
(1000 to 1300 kPa)
Maximum difference
between cylinders
14 psi (100 kPa)
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