ALLISON-OM1334EN

found in the sump or on the magnetic plate in the bottom of the pan (if present), the

transmission must be disassembled and closely inspected to find the source. Metal

contamination requires complete disassembly of the transmission and cleaning of all

internal and external circuits, cooler, and all other areas where the particles could

lodge. (Refer to Auxiliary Filter.)

Coolant Leakage

If engine coolant leaks into the transmission hydraulic system, take 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 coolant contamination. Replace friction clutch plates contaminated

with ethylene glycol.

Fluid Analysis

Transmission protection and fluid change intervals can be optimized by transmission

fluid analysis. Consult your local telephone directory for fluid analysis firms. Use one

fluid analysis firm as results from various firms cannot be accurately compared. Refer

to the Technicians’ Guide for Automatic Transmission Fluid (SA2055) for additional

information.

To optimize transmission protection, the following is the minimum series of tests

required to properly monitor the condition of the transmission and transmission

fluid/filter system.

• Wear Metals (ppm): Fe, Cu, Pb, Al

• Additive and Contaminant Metals (ppm): Ba, B, Ca, Mg, P, Si, Na, Zn

• Non-metal Contaminants: Fuel (% vol), Soot (% wt), Water (% vol)

• Viscosity (cSt) at 40˚C

(ASTM D445)

• Viscosity (cSt) at 100˚C

(ASTM D445)

• TAN (Total Acid Number)

(ASTM D664)

• Particle Counts (particles/ml) at >5, >10, >20, >30, and >40 microns

ppm = parts per million

cSt = centiStokes

ml = milliliter

To optimize fluid change intervals, monitor fluid oxidation per the tests and limits

shown in Table 4. A fluid is considered suitable for use if it meets all four limits listed

in the table, regardless of color or odor. If

one

of the limits is exceeded, however, the

ALLISON AT, MT, HT SERIES ON-HIGHWAY TRANSMISSIONS

OPERATOR'S MANUAL

2000