Power Unit; Power Unit (Check And Adjustment); Checking The Compression Pressure; Checking The Oil Pressure - Yamaha F30A Service Manual

POWR
Power unit (check and
adjustment)

Checking the compression pressure

1. Start the engine, warm it up, and then
turn it off.
2. Remove the clip from the engine shut-off
switch.
3. Disconnect the spark plug caps, remove
the spark plugs, and then install the spe-
cial service tool 1 into a spark plug hole.
1
CAUTION:
Before removing the spark plugs, remove
any dirt or dust in the spark plug wells
that may fall into the cylinders.
Compression gauge 1:
90890-03160
4. Turn the throttle grip or move the remote
control lever to the fully open position.
5. Crank the engine until the reading on the
compression gauge stabilizes, and then
measure the compression pressure.
NOTE:
Since this outboard motor is equipped with
an automatic decompression mechanism,
the compression pressure may vary depend-
ing on the speed at which the starter handle
is pulled when using the manual starter to
crank the engine. (M and W model)
5-1

Power unit

S67C5001
Minimum compression pressure
(reference data):
600 kPa (6.0 kgf/cm
(M and W model)
830 kPa (8.3 kgf/cm
(E model)
6. If the compression pressure is below
specification or the compression pres-
sure for each cylinder is unbalanced, add
a small amount of engine oil to the cylin-
der, and then measure the pressure
again.
NOTE:
• If the compression pressure increases,
check the pistons and piston rings. Replace
if worn.
• If the compression pressure does not
increase, check the valve clearances,
valves, valve seats, cylinder sleeves, cylin-
der head gasket, and cylinder head. Adjust
or replace if necessary.
7. Repeat steps 4–6 for each cylinder.

Checking the oil pressure

1. Remove the oil pressure switch, and then
install an oil pressure gauge 1 to the oil
pressure switch installation hole.
NOTE:
Use a commercially available oil pressure
gauge 1.
2. Start the engine and warm it up for 10
minutes.
2
, 87.0 psi)
2
, 120.4 psi)
1
S67C5002
67C3K11