Transmission Fluid Leak Check
Perform oil leak checks after inspecting the condition and level of the automatic transmission fluid. Transmission fluid can become discolored and turn a brown color similar to oil. After checking the condition and level of the fluid raise the vehicle on a hoist. Visually inspect areas where parts meet like the oil pan, the area around the pump and torque converter and the extension housing. Overheated, aerated or overfilled fluid levels will result in fluid leaking from the transmission vent. Look behind the torque converter cover for a leaking oil pump seal and visually inspect the axle seals for leakage.
Fluid levels have an affect on fluid flow and pressures. Low fluid levels result in air being drawn into the oil pump passages, filling it with tiny air bubbles. This condition is referred to as aeration and results from low or high fluid levels. When the level is high the spinning planetary gearsets aerate the fluid. This causes damaging clutch and band slippage, buzzing sounds from pressure valves, and affects valve, clutch and TCC operation. Varnish on the dipstick indicates fluid oxidation. Oxidation coats interior transmission parts and causes components like shift and pressure valves to stick.