Compression (3.0L) - Mazda B-Series 1997 Workshop Manual

COMPRESSION
COMPRESSION
If the engine exhibits low power, poor fuel economy, or
poor idle, check the following:
1. Ignition system (Refer to Section G.)
2. Compression (Refer to below.)
3. Fuel system (Refer to Section F2.)
INSPECTION
1. Verify the battery is fully charged. Recharge it if neces-
sary.
2.
Warm up the engine to the normal operating temperature.
3. Remove the spark plugs.
4. Disconnect the harness connector f~rom the ignition coil.
5. Connect a compression gauge to N13.1 spark plug hole.
6. Fully depress the accelerator pedal and crank the engine.
7. Note the maximum gauge reading.
8. Check each cylinder as above.
Compression:
Lowest reading cylinder is within 75 percent of
the highest. (Refer to Section T'D.)
9. If the compression in one more cylinders is low, pour a
small amount of engine oil into the cylinder and recheck
the compression.
(1) If the compression increases, the piston, piston rings,
or cylinder wall may be worn.
(2)
If the compression stays low, the valve may be stuck
or seating improperly.
(3) If the compression in adjacent cylinders stays low, the
cylinder head gasket may be damaged or the cylinder
head distorted.
10. Connect the harness connector to the ignition coils.
11. Install the spark plugs.
Note
If installing the original spark plugs, install them in
their original locations.
LH BANK: WHITE
RH BANK: DARK GREEN
Tightening torque:
9-20 N
.
rn (0.9-2.0
kgf
.
m, 7-1 5 ft
-
Ibf)