What should be done to the transmission cooler before connecting a new automatic transmission?

Flushing the transmission cooler before connecting a new automatic transmission is essential for ensuring that any debris, contaminants, or old transmission fluid that may have accumulated are removed. During the operation of an automatic transmission, wear particles and sediment can build up over time, which can dramatically affect the performance and longevity of a new transmission.

By flushing the cooler, you help prevent any remaining contaminants from circulating through the new transmission system. This maintenance step is particularly important as these foreign materials can lead to clogs, overheating, or even premature failure of the new transmission.

While visually inspecting the cooler is a good practice, it does not guarantee the removal of internal contaminants. Draining and filling would not address contaminants stuck in the cooler itself, and replacing the cooler may not be necessary if a thorough flush removes all debris. Thus, flushing ensures a clean environment for the new transmission, promoting optimal performance right from the start.