6–11 Cooler Flushing

Metal contamination requires complete transmission disassembly and cleaning. Clean all internal and external hydraulic circuits, transmission cooler, and all areas where metal and other particles could lodge. Special tool J 46550 Transmission Cooler Kwik-Flush Cart is now an essential tool for all overhaul and maintenance service outlets, J 46550 or an approved cooler flushing device that meets Allison cooler flushing requirements and procedures must be used.

1. Flush contaminated fluid from the cooler by flowing transmission fluid through the cooler in the reverse direction of normal flow. Use a flushing pump that pumps fluid in a pulsating flow at a minimum mean rate of 0.5 liters/sec (8.0 gpm) and 275–345 kPa (40–50 psi). The J 46550

Transmission Cooler Kwik-Flush Cart meets these requirements. 2. After flushing the contaminated fluid, use the flushing pump to circulate clean transmission fluid through the cooler in a closed loop back to a 10-micron filter. Circulate fluid in the closed loop for a minimum of five minutes.

CAUTION: After flushing the cooler, be sure to check the external cooler circuit restriction. If circuit pressure drop is above specification, the cooler has excessive trapped particles and must be replaced.