Transmission vent hose leaking fluid

[Kavi]

1. I have recently bought a Yaris 1.0 (yr 2005). Being a novice I asked the mechanic to change the fluid of the automatic transmission. The mechanic overfilled it as the fluid is foamy and leaks out of the transmission hose vent only when engine is cold and idling. Is it bad for my transmission or is there anything I can do by myself?

[R2D2]

Yes it is bad for the transmisson. The fluid is being churned by the moving internal parts of the transmisson. The problem with this (besides the obvious mess) is the entrained air is making the fluid a less effective lubricant. This increases wear and heat production. The air bubbles also expose more surface area of the fluid to heat and oxygen which drastically increase the oxidation rate of the fluid, causing it to degrade much more quickly.

You could try to estimate the amount it is overfilled and drain fluid out the trans pan drain plug in small increments to bring the level into the proper range. You could also return it and have the shop correct it since they overfilled it, ASAP.

[GeneW]

The mechanic overfilled it as the fluid is foamy and leaks out of the transmission hose vent only when engine is cold and idling. Is it bad for my transmission or is there anything I can do by myself?

Either Mr. Badwrench over filled it or they put the wrong fluid in. My 2008 takes some sort of "WTS" grade of fluid. Anything is else bad news. I imagine that the same thing goes for earlier models.

I'd have it towed to either the Mechanic or to a professional tranny shop. I would not under any circumstances but an emergency drive it at all.

Gene