Allison Transmission 3000 Mechanic's Tips page 40

4. Visually inspect the suspected area and trace the leak path over the white
powder.
c. Black light and Dye Method. A dye and black light kit for finding leaks is
available. Refer to the manufacturer's directions when using the kit. Refer to the
kit directions for the color of the fluid/dye mix.
1. Pour the specified amount of dye into the transmission fill tube.
2. Operate the vehicle under normal operating conditions.
3. Direct the black light toward the area suspected of leaking. Dyed fluid will
appear as a brightly colored path leading to the leak.
d. Repairing the Leak. Once the leak has been traced back to its source,
inspect the leaking part for the following conditions, and repair the leaking part.
• Gaskets:
— Fluid level/pressure is too high
— Plugged vent or drain-back holes
— Improperly tightened fasteners or damaged threads
— Warped flanges or sealing surfaces
— Scratches, burrs, or other damage to sealing surfaces
— Damaged or worn-out gasket
— Cracked or porous casting
— Improper sealant used, where applicable
• Seals:
— Fluid level/pressure is too high
— Plugged vent or drain-back hole
— Damaged seal bore
— Damaged or worn-out seal
— Improper seal installation
— Cracks in component
— Output shaft surface scratched, nicked, or damaged
— Loose or worn-out bearing causing excess seal wear
• Sealing Flange:
— Inspect the sealing flange for bends
— Replace the sealing flange if bent
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