During a cold transmission check, how long should the engine run to purge air from the fluid system?

• A. 30 seconds
• B. 1 minute
• C. 2 minutes
• D. 5 minutes

Answer: (B)

Purge air from the transmission fluid by letting the engine run long enough for the pump to circulate fluid through the system and push trapped air out. About one minute at idle gives the pump time to move fluid through the cooler and valve body, clearing air pockets so the level reading reflects the actual fluid. Too short a run may leave air in the lines, giving an inaccurate reading, while running much longer can allow the fluid to heat up and alter the cold-reading reference. One minute is the standard duration to achieve a proper purge without affecting the cold check.