CAUTION:
Transmission
fl
uid and
fi
lters
must be changed
whenever
there is evidence of dirt or a high temperature condition. A high
temperature condition is indicated when the transmission
fl
uid is
discolored, has a strong odor, or has exceeded oil analysis limits.
Fluid Analysis
Transmission protection and
fl
uid change intervals may be optimized by
monitoring
fl
uid oxidation according to the tests and limits shown in the Fluid
Oxidation Measurement Limits table. Consult your local telephone directory for
fl
uid analysis
fi
rms. To be sure of consistent and accurate
fl
uid analysis, use only
one
fl
uid analysis
fi
rm. Refer to Technician’s Guide for Automatic Transmission
Fluid, GN2055EN, for additional information.
Fluid Oxidation Measurement Limits
Test
Limit
Viscosity
±
25 percent change from new
fl
uid
Total Acid Number (TAN)
+3.0* change from new
fl
uid
Solids
2 percent by volume
* mg of potassium hydroxide (KOH) to neutralize a gram of
fl
uid.
TRANSMISSION FLUID CONTAMINATION
Fluid Examination.
At each
fl
uid change, examine the drained
fl
uid for evidence
of dirt or water. A normal amount of condensation will appear in the
fl
uid during
operation.
Water.
Obvious water contamination of the transmission
fl
uid or transmission
fl
uid in the cooler (heat exchanger) water indicates a leak between the water and
fl
uid areas of the cooler. Inspect and pressure test the cooler to con
fi
rm the leak.
Replace leaking coolers.
NOTE:
Cooler water can also be contaminated by engine oil; be sure to
locate the correct source of cooler water contamination.
Engine Coolant.
Engine coolant in the transmission hydraulic system requires
immediate action to prevent malfunction and possible serious damage. An
authorized Allison service outlet must completely disassemble, inspect, and clean
the transmission. All traces of the coolant, and varnish deposits resulting from
engine coolant contamination must be removed. Friction clutch plates
contaminated with engine coolant (ethylene glycol) must be replaced.
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