What should be checked when inspecting the transmission?

When inspecting the transmission, checking for leaks with the motor running in 'neutral' is essential for several reasons. First, having the engine running allows the transmission fluid to circulate, providing a more accurate representation of fluid levels and potential leaks under operating conditions. When the transmission is in 'neutral', it allows the fluid to flow freely through the system without engaging the gears, enabling a thorough inspection of gaskets, seals, and connections for any signs of leakage.

Additionally, this method helps in identifying thermal expansion effects that may reveal issues not present when the engine is off or when the vehicle is in gear. This practice is fundamental to ensuring the transmission system functions efficiently and prolongs the lifespan of the vehicle, as leaks can lead to inadequate fluid levels, which can cause significant transmission damage over time.

Other methods—while they may check fluid levels or leaks—do not effectively simulate the conditions under which the transmission operates, making them less reliable for a comprehensive inspection.