b. Abnormal Conditions. Transmissions used in high cycle rate applications should use fluid analysis to be certain that a proper fluid change interval is established. Transmission fluid must be changed whenever there is evidence of dirt or a high temperature condition. A high temperature condition is indicated by the transmission fluid being discolored or having a strong odor, or by fluid analysis. Local conditions, severity of operation, or duty cycle may require more or less frequent fluid or filter change intervals. c. Fluid Analysis. Transmission protection and fluid change intervals can be optimized by monitoring fluid oxidation according to the tests and limits shown in Table 1–3. Consult your Distributor/Dealer for an Oil Analysis Kit (refer to SIL 17-TR-96, Rev A). To be sure of consistent and accurate fluid analysis, use only one fluid analysis firm. Refer to the Technician’s Guide for Automatic Transmission Fluid, GN2055EN, for additional information. Table 1–3. Fluid Oxidation Measurement Limits
Test Viscosity Total Acid Number
Limit ±25% change from new fluid +3.0 change from new fluid
1–7. TRANSMISSION FLUID CONTAMINATION a. Fluid Examination. At each fluid change, examine the drained fluid for evidence of dirt or water. A normal amount of condensation will appear in the fluid during operation. b. Water. Obvious water contamination of the transmission fluid or transmission fluid in the heat exchanger coolant indicates a leak between the water and fluid areas of the cooler. Inspect and pressure test the cooler to confirm the leak. Replace leaking coolers. NOTE: Coolant can also be contaminated by engine oil; be sure to locate the correct source of coolant contamination.
c. Engine Coolant. CAUTION: Engine coolant in the transmission hydraulic system requires immediate action to prevent malfunction and possible serious damage. Completely disassemble, inspect, and clean the transmission. Remove all traces of the coolant, and varnish deposits resulting from engine coolant contamination. Refer to SIL 18-TR-98 for more information. 13
