Automatic Transmission

When the fluid level is too high it will get whipped around by the rotating drums and become aerated. The bubbles will go up high enough to reach the vent in the front pump right behind the torque converter. From there it will run down and appear to be a leak. If you ignore it long enough the level will go down to the point that happens less often but aerated fluid will cause other damage. Since the air in the fluid can compress, shift valves which move from fluid pressure won't move smoothly or at the right times, and since the clutch plates have pressure applied to engage them by fluid pressure they will not apply hard enough and slippage will occur between the fiber and steel plates. That will quickly lead to overheating of the plates and permanent damage and more slipping.

One potential cause of sticking in second gear too long is varnish buildup in the governor valve or valve body. There is always the possibility that can be solved by adding a small can of additive designed to dissolve that varnish. Use a hand vacuum pump with a hose to draw the extra fluid out through the dip stick tube, then add the chemical. It might save you the cost of a transmission repair or an expensive rebuild.

There is always the possibility that can be solved by adding a small can of additive designed to dissolve that varnish. Use a hand vacuum pump with a hose to draw the extra fluid out through the dip stick tube, then add the chemical.