Questions and Answers

Trans Fluid Overfill

Q. I have a 1979 Camero with a 350ci and a TH-400 transmission. The trans is an older version from around the late 60's - early 70's. It works fine except that I accidentally overfilled it by about a half a quart. Will this trans just blow it out the vent?? And after that then the fluid went from bright red to a little tint of brown. but still really red. The fluid is new including the torque converter. Could it just be dirt stirring up since it was overfilled?? I don't have the electric kick down connected, but it still downshifts when I hit hills or mash the gas. Do I really need it hooked up?? Since I heard that the switch is just a solenoid that kicks in when the carb is at full throttle and triggers a switch. And since I hardly ever have to mash the gas it wouldn't get used anyhow??? Thanks for your help.

A. A pint over will not usually hurt the transmission. The danger of overfilling the transmission is that the fluid will foam up and push air through the transmission causing it to burn up. When you change the transmission fluid, you never get ALL the old fluid out. The torque converter holds about six quarts of fluid and unless you drill out the converter and install a drain plug, no more than half the fluid will drain out of it. If the color is a little brownish, then don't worry about it. If it looks just as bad as it did before you changed it, then you might want to consider changing it again. Or possibly taking it to a transmission shop and having it flushed.

The older TH-400's used a vacuum kick down switch, so if the electric one is not connected, no big deal.