Compression - Mazda B-Series 1997 Workshop Manual

COMPRESSION
B1
COMPRESSION
If the engine exhibits low power, poor fuel economy, or poor idle, check the following:
1. Ignition system (Refer to Sectiori G.)
2. Compression (Refer to below.)
3. Fuel system (Refer to Section FT.)
INSPECTION
1. Verify that the battery is fully charged. Recharge it if
necessary. (Refer to Section G.)
2.
Warm up the engine to the normal operating temperature.
3. Stop the engine and allow it to cool for about 10 minutes.
4. Remove the spark plugs on the exhaust side only.
5.
Disconnect the harness connectors from the ignition coils.
6. Connect a compression gauge to Nu. 1 spark plug hole.
7.
Fully depress the accelerator pedal and crank the engine.
8. Note the maximum gauge reading.
9. Check each cylinder as above.
MB1239-A
Compression:
Lowest reading cylinder within 75 percent of the
highest. (Refer to Section TD.)
10. If the compression in one or 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.
~ ~ 1 2 4 9 - A
~BUOBI-003
(3) If the compression in adjacent cylinders stays low, the
cylinder head gasket may be damaged or the cylinder
head distorted.
11. Connect the harness connectors to the ignition coils.
12. Install the spark plugs.
Tightening torque:
7-14 N.m (0.7-1.4 kgf-m, 5-10 ft-lbf)