RAM 3500 Truck 2WD L6-5.9L DSL Turbo (2008)
Fluid - A/T: Testing and Inspection
48RE Automatic Transmission
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.
Causes Of Burnt Fluid
CAUSES OF BURNT FLUID
Burnt, discolored fluid is a result of overheating which has two primary causes.
1. A result of restricted fluid flow through the main and/or auxiliary cooler. This condition is usually the result of a faulty or improperly installed
drainback valve, a damaged oil cooler, or severe restrictions in the coolers and lines caused by debris or kinked lines.
2. Heavy duty operation with a vehicle not properly equipped for this type of operation. Trailer towing or similar high load operation will overheat
the transmission fluid if the vehicle is improperly equipped. Such vehicles should have an auxiliary transmission fluid cooler, a heavy duty cooling
system, and the engine/axle ratio combination needed to handle heavy loads.
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 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 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.
