F 150 2WD Pickup V8-5.4L SOHC VIN 3 (1999)
Compression Check: Testing and Inspection
1. Make sure the oil in the crankcase is of the correct viscosity and at the proper level and that the battery is properly charged. Operate the vehicle
until the engine is at normal operating temperature. Turn the ignition switch to the OFF position, then remove all the spark plugs.
2. Set the throttle plates in the wide-open position.
3. Install a compression gauge such as the Compression Tester in the No. 1 cylinder.
4. Install an auxiliary starter switch in the starting circuit. With the ignition switch in the OFF position, and using the auxiliary starter switch, crank
the engine a minimum of five compression strokes and record the highest reading. Note the approximate number of compression strokes required
to obtain the highest reading.
5. Repeat the test on each cylinder, cranking the engine approximately the same number of compression strokes.
Compression Pressure Limit Chart
Compression Pressure Limit Chart
The indicated compression pressures are considered within specification if the lowest reading cylinder is within 75 percent of the highest reading.
If one or more cylinders reads low, squirt approximately one tablespoon of Super Premium SAE 5W30 Motor Oil, X0-5W30-QSP meeting Ford
specification WSS-M2C153-G on top of the pistons in the low-reading cylinders. Repeat the compression pressure check on these cylinders.
-
If compression improves considerably, piston rings are faulty.
-
If compression does not improve, valves are sticking or seating improperly.
-
If two adjacent cylinders indicate low compression pressures and squirting oil on each piston does not increase compression, the head gasket may
be leaking between cylinders. Engine oil or coolant in cylinders could result from this condition.
