239
Powerhead
Compression Testing
11
Compression Testing
Start and run outboard until it achieves operating
temperature, then shut OFF.
Disconnect crankshaft position sensor (CPS) con-
nector. Remove all spark plugs.
Install compression tester’s hose attachment into
spark plug hole (14 mm threads).
Turn the key switch to the ON position.
While cranking outboard with starter, note maxi-
mum pressure reading on gauge. Repeat proce-
dure for each cylinder.
If engine shows a variation greater than 15 psi
(100 kPa) between cylinders, check for:
• damaged cylinder head
• damaged pistons
• broken or stuck piston rings
• scored cylinder walls
Return throttle to idle position and reconnect CPS
connector. Replace spark plugs.
Powerhead Removal
Procedure
IMPORTANT: Before removing the powerhead
trim the engine to the vertical position.
Remove the top engine cover. Then remove the 4
inch plug from the center frame. Next remove the
3.5 inch plug from the air duct and the thread pro-
tector from the flywheel threads.
Remove the front cover. Then disconnect all
cables, buss cables and hoses from the engine.
Remove the rear cover, starboard and port frames
and front frame. Refer to Engine Cover and
Frame Service on p. 55.
Remove the rigging grommets from the power-
head.
WARNING
Protect against hazardous fuel spray. Before
starting any fuel system service, carefully
relieve fuel system pressure. Refer to Reliev-
ing Fuel System Pressure on p. 168.
To prevent accidental starting while servic-
ing, twist and remove spark plug leads.
Engine in Vertical Position
009167
1. 4 inch plug
2. 3.5 inch plug
3. Thread protector
009168
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