I checked my tranny fluid yesterday with car running and made sure I ran through the gears first and when I removed plug fluid started pouring out! Not just a little but a lot!! So my question is can too much fluid cause transmission to slipp or hurt transmission?

 

was your car just running or did you get it up to operating temperature?

 

If you had a dipstick, you could put way too much in it, and you'd run the risk of blowing out seals.

With our fill plug, you cannot really over fill it by enough to worry about. The last person to fill it probably jacked up one side for more room and got a little extra in. Or maybe the used a two post lift and when they pick it up by the frame it wasn't level.

I wouldn't worry about it.

 

I would be concerned about how much "poured out". Ditto on jacking one side of the truck up to squeeze a few more ounces in. In fact, thats what I did to my rig.

 

Been there, done that!

Was the car dead cold when you did this? It needs to be, otherwise fluid will be shooting out the fill hole, making it appear AS IF it is overfilled, when in reality it isn't. In fact, chances are you now have too little fluid.

Let the car sit overnight, then when it is completely cool, do the following (from RAVE):

8. Remove oil filler/level plug, remove and discard
sealing washer.
9. Fill gearbox with recommended oil to bottom of
oil level/filler plug hole.
10. Select 'P' (Park).
11. Ensure handbrake is applied.
12. Start engine and allow it to idle.
13. Apply footbrake.
14. Move selector lever through all gear positions,
while continuing to fill the gearbox. Select 'P'
(Park).
15. With engine idling, continue filling gearbox until
a 2 mm bead of oil runs from oil filler/level plug
hole.
16. Fit new sealing washer to automatic gearbox
filler/level plug, fit plug and tighten to 30 Nm (22
lbf.ft).
17. Stop engine.
18. Remove all traces of oil from gearbox casing.

A couple notes. First, it is good to have a helper in the car to run through the gears while you are filling the transmission. Second, each gear should be selected and held for about 30 sec or so to ensure fluid circulates thoroughly.