Grand Cherokee 4WD V8-4.7L (2003)
Fluid - A/T: Testing and Inspection
42RE (A-500) 4 Speed
Effects of Incorrect Fluid Level
EFFECTS OF INCORRECT FLUID LEVEL
A low fluid level allows the pump to take in air along with the fluid. Air in the fluid will cause fluid pressures to be low and develop slower than
normal. If the transmission is overfilled, the gears churn the fluid into foam. This aerates the fluid and causing the same conditions occurring with a
low level. In either case, air bubbles cause fluid overheating, oxidation and varnish buildup, which interferes with valve and clutch operation. Foaming
also causes fluid expansion, which can result in fluid overflow from the transmission vent or fill tube. Fluid overflow can easily be mistaken for a leak
if inspection is not careful.
Fluid Contamination
FLUID CONTAMINATION
Transmission fluid contamination is generally a result of:
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adding incorrect fluid
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failure to clean dipstick and fill tube when checking level
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engine coolant entering the fluid
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internal failure that generates debris
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overheat that generates sludge (fluid breakdown)
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failure to reverse flush cooler and lines after repair
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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, an overhaul is necessary.
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.