Contents Section: Mechanical All sections

4.0L Engine: Overhaul Jeep Cherokee II рестайлинг

Mechanical 1 illustration ~166 words

Piston & Rod Assembly

CAUTIONDO NOT substitute old style pistons for new coated pistons. New coated pistons are supplied pre-assembled with piston, piston pin and connecting rod as a unit and must be replaced as a complete set. New coated piston/connecting rod assembly can be used to service older engines, but must be replaced as complete sets.

Scheme 17

Scheme 17
  1. To correctly select proper size piston, a Cylinder Bore Gauge (6879), capable of reading in.0001" increments with Gauge Ring (6884) is required. If a suitable dial bore gauge is not available, DO NOT substitute an inside micrometer.
  2. Using gauge ring, zero dial bore gauge. Using dial bore gauge, measure cylinder bore and record readings. Measure cylinder bore 1 5/16" (49.5 mm) below top of bore in line with axis of crankshaft ("A"). Take a second reading at 90 degrees to first reading ("B"). (Scheme 17)
  3. Recheck zero of bore gauge in gauge ring. If gauge does not read zero, reset and repeat measurements.
  4. Measuring inside diameter of cylinder bore with a.0001" reading dial bore gauge is mandatory to obtain correct clearance. See «CYLINDER BORE & PISTON IDENTIFICATION»(ref-2578-S12115559122000032000000) table. Piston installation into cylinder bore requires slightly more pressure than for non-coated pistons. Coating will give appearance of a 0-0 fit in cylinder bore.
Bore SizePiston ID
3.8755-3.8759""A"
3.8759-3.8763""B"
3.8763-3.8767""C"
3.8767-3.8771""D"
3.8771-3.8775""E"
3.8775-3.8779""F"

CYLINDER BORE & PISTON IDENTIFICATION