Jeep Cherokee
 Service Manual
Transmission and transfer case » AW-4 automatic transmission » Diagnosis and testing
Fluid contamination

Transmission fluid contamination is generally a result of:

  •  adding incorrect fluid
  • failure to clean dipstick and fill tube when checking level
  •  engine coolant entering the fluid
  •  internal failure that generates debris
  •  overheat that generates sludge (fluid breakdown)
  •  failure to reverse flush cooler and lines after repair
  •  failure to replace contaminated converter after repair

The use of non recommended fluids can result in transmission failure. The usual results are erratic shifts, slippage, abnormal wear and eventual failure due to fluid breakdown and sludge formation. Avoid this condition by using recommended fluids only.

The dipstick cap and fill tube should be wiped clean before checking fluid level. Dirt, grease and other foreign material on the cap and tube could fall into the tube if not removed beforehand. Take the time to wipe the cap and tube clean before withdrawing the dipstick.

Engine coolant in the transmission fluid is generally caused by a cooler malfunction. The only remedy is to replace the radiator as the cooler in the radiator is not a serviceable part. If coolant has circulated through the transmission for some time, an overhaul may also be necessary; especially if shift problems had developed.

The transmission cooler and lines should be reverse flushed whenever a malfunction generates sludge and/or debris. The torque converter should also be replaced at the same time.

Failure to flush the cooler and lines will result in recontamination. Flushing applies to auxiliary coolers as well. The torque converter should also be replaced whenever a failure generates sludge and debris. This is necessary because normal converter flushing procedures will not remove all contaminants.

    More about «Diagnosis and testing»:

    General diagnosis information

    Effects of incorrect fluid level

    Causes of burnt fluid

    Fluid contamination

    Preliminary inspection and adjustment

    Manual shifting test

    Hydraulic pressure test

    Pressure test analysis

    Time lag test

    Test procedure

    Time lag test analysis

    Service diagnosis

    Transmission solenoid testing

    Park/neutral position switch

    Gearshift cable

    Throttle valve cable

    Speed sensor testing

    Flow testing transmission main cooler

    Torque converter stator clutch inspection

    Jeep Cherokee Service Manual / Transmission and transfer case / AW-4 automatic transmission / Diagnosis and testing / Fluid contamination

    Jeep Cherokee Service Manual


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