During a stall test, if the transmission fluid does not cool down during the cool-down phase, which technician is correct?

During a stall test, if the transmission fluid does not cool down during the cool-down phase, which technician is correct?

• A. Technician A
• B. Technician B
• C. Both Technician A and Technician B
• D. Neither Technician A nor Technician B

Answer: (B)

In a stall test, you’re looking at how heat is rejected from the transmission fluid. When the engine is held at stall, the transmission fluid heats up from the work being done inside. Once you release the load and let things cool, the fluid should drop in temperature as heat is removed by the cooling system. If the fluid does not cool during the cooldown phase, it means heat isn’t being removed effectively. That points to a problem in the cooling path—such as a faulty transmission cooler, clogged cooler lines, insufficient coolant flow, a malfunctioning radiator fan, or low coolant level. The issue is with heat rejection, not necessarily with internal transmission components under load. So that conclusion aligns with the technician who focused on the cooling system as the source of the problem. To verify, inspect the cooling circuit and components: radiator and external cooler, hoses and lines, coolant level, and the radiator fan operation, and check for any blockages or leaks.