Vacuum testing beyond valve body Archives - Transmission Digest
Seal the Deal: Preventing Comebacks with Non-Valve-Body Vacuum Testing

Vacuum testing is not a new process in the automotive field. After engine builders “lapped” a sealable mating surface between valves and their seats, they would use vacuum to test for any leaks that needed to be addressed. Vacuum testing is relatively new to the transmission rebuilding industry, though.