S15/T15 4WD Jimmy L4-151 2.5L (1985)
Compression Check: Testing and Inspection
COMPRESSION CHECK
-
Disconnect the primary terminal from the ignition coil.
-
Remove all spark plugs.
-
Block the throttle plate wide open.
-
Make sure the battery is fully charged.
-
Starting with the compression gauge at zero, crank the engine through four compression strokes (four "puffs").
-
Make the compression check at each cylinder and record each reading.
-
If some cylinders have low compression, inject 15 ml (one table spoon, or 3 squirts from a pump type oil can) of engine oil into the combustion
chamber through the spark plug hole.
-
See Specifications for minimum pressure and maximum variation. See: Specifications
Normal Compression: Compression builds up quickly and evenly to specified compression on each cylinder.
Piston Rings Leaking: Compression low on first stroke, tends to build up on following strokes, but does not reach normal. Improves
considerably with addition of oil.
Valves Leaking: Low on first stroke. Does not tend to build up on following strokes. Does not improve much with addition of oil.
Head Gasket Leakage: If two adjacent cylinder have lower than normal compression, and injecting oil into cylinders does not increase the
compression, the cause may be a head gasket leak between the cylinders.
