Mazda 6. Manual - part 104
COMPRESSION PRESSURE
B–9
B
COMPRESSION INSPECTION
A6E221402000W01
Warning
• Hot engines and oil can cause severe burns. Be careful not to burn yourself during removal/
installation of each component.
1. Verify that the battery is fully charged.
• Recharge it if necessary. (See
2. Warm up the engine to the normal operating temperature.
3. Stop the engine and allow it to cool off for about 10 min.
4. Perform “Fuel Line Safety Procedures”. Leave the fuel pump relay removed. (See
Warning
• Fuel vapor is hazardous. It can very easily ignite, causing serious injury and damage. Always keep
sparks and flames away from fuel.
• Fuel line spills and leakage are dangerous. Fuel can ignite and cause serious injuries or death and
damage. Fuel can also irritate skin and eyes. To prevent this, always complete the “Fuel Line
Safety Procedure”. (See
F–17 Fuel Line Safety Procedure
5. Remove the ignition coil connector.
6. Remove the spark plugs. (See
7. Connect a compression gauge into the spark plug
hole.
8. Fully depress the accelerator pedal and crank the
engine.
9. Note the maximum gauge reading.
10. Inspect each cylinder as above.
• If the measured value is less than the limited
value, or there is a cylinder whose
compression value varies from that of other
cylinders by 196.1 kPa {1.999 kgf/cm
2
, 28.44
psi} or more, add a small amount of engine oil
through the spark plug hole. Then measure
the compression pressure and perform the
respective operations for the following cases.
— If the compression increases, the piston,
the piston rings, or cylinder wall may be
worn and overhaul is required.
— If the compression stays low, a valve may be stuck or improperly seated and overhaul is required.
— If the compression in adjacent cylinders stays low, the cylinder head gasket may be damaged or the
cylinder head distorted and overhaul is required.
Compression
kPa {kgf/cm
2
, psi} [rpm]
kPa {kgf/cm
2
, psi} [rpm]
COMPRESSION PRESSURE
Item
Engine type
L8
Standard
1,750 {17.845, 253.816} [300]
Minimum
1,225 {12.492, 177.64} [300]
Maximum difference
between cylinders
196.1 {1.999, 28.44}
Item
Engine type
LF
Standard
1,720 {17.5391, 249.465} [300]
Minimum
1,204 {12.277, 174.58} [300]
Maximum difference
between cylinders
196.1 {1.999, 28.44}
AME2214W001