Contents Wiring diagrams Section: Mechanical All sections

4.0L Engine: Diagnosis Jeep Wrangler II

Mechanical ~368 words

TROUBLE SHOOTING

Note. To trouble shoot mechanical engine components, see appropriate table in TROUBLE SHOOTING article in GENERAL INFORMATION.

Inspection

  1. Inspect cylinder head for cracks and damage. Using straightedge, check cylinder head for warpage across bolt holes and diagonals. Repair or replace cylinder head if warpage exceeds specification or damage exists. See «CYLINDER HEAD»(ref-98248-S37815619182001051800000) table under ENGINE SPECIFICATIONS.
  2. Cylinder head bolts may only be reused once. If this is first time cylinder head has been removed, mark each bolt head with paint. If bolts are already marked or if it is unknown whether head bolts have been used before, discard and replace with NEW head bolts.

Inspect lobes, journals, bearings and distributor drive gear for wear. Inspect valve lifters for abnormal wear. If camshaft sprocket or chain rubs against engine front cover, examine oil pressure relief holes in rear camshaft journal and ensure they are free of debris. Replace components as necessary. If camshaft requires replacement, valve lifters must also be replaced.

The radiator cooling fins should be checked for damage or deterioration. Inspect cooling fins to make sure they are not bent or crushed, these areas result in reduced heat exchange causing the cooling system to operate at higher temperatures. Inspect the plastic end tanks for cracks, damage or leaks.

Inspect the radiator neck for damage or distortion.

Cylinder Bore Inspection

  1. Using a dial bore gauge, measure each cylinder bore diameter. If a dial bore gauge is not available, DO NOT substitute an inside micrometer. See «PISTON & ROD ASSEMBLY»(ref-98248-S29451810312001051800000) .
  2. Measure cylinder bore at 90 degrees to crankshaft near top of bore. Repeat measurement near middle and bottom of bore. Determine taper by subtracting the smaller diameter from the larger.
  3. Rotate bore gauge 90 degrees and repeat measurements. Determine out-of-roundness by comparing difference between each measurement.
  4. If cylinder bore taper does not exceed .001" (.025 mm) and out-of-roundness does not exceed .001" (.025 mm), cylinder bore can be honed. If cylinder bore taper or out-of-round exceeds these limits, cylinder must be bored and honed to accept an oversize piston. NOTE: A slight amount of taper always exists in the cylinder bore after an engine has been in use for a period of time.