Sable V6-183 3.0L VIN U FI (1998)
Compression Check: Testing and Inspection
COMPRESSION GAUGE CHECK
1. Make sure oil in crankcase is of the correct viscosity and at proper level and battery is properly charged. Operate vehicle until engine is at normal
operating temperature. Turn ignition switch to the OFF position and remove all spark plugs.
2. Set throttle plate in wide-open position.
3. Install a compression gauge such as Rotunda Air Pressurization Kit 303-F011 (014-00707) or equivalent in No.1 cylinder.
4. Install auxiliary starter switch in starting circuit. With ignition switch OFF, using auxiliary starter switch, crank 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 test on each cylinder, cranking the engine approximately the same number of compression strokes.
TEST RESULTS
The indicated compression pressures are considered within specification if the lowest reading cylinder is within 75 percent of the highest reading.
Refer to the separate Compression Pressure Limit Charts.
If one or more cylinders reads low, squirt approximately one tablespoon of clean engine oil meeting Ford specification WSS-M2C153-F on top of the
pistons in the low-reading cylinders. Repeat compression pressure check on these cylinders.
COMPRESSION READINGS-INTERPRETING
1. If compression improves considerably, piston rings are faulty.
2. If compression does not improve, valves are sticking or seating poorly.
3. If two adjacent cylinders indicate low compression pressures and squirting oil on pistons does not increase compression, the head gasket may be
leaking between cylinders. Engine oil and/or coolant in cylinders could result.
Check the appropriate Compression Pressure Limit Chart when checking cylinder compression.
EXAMPLE READINGS