Changed transmission fluid 6hp26 but something strange happened.
 

I have the 2007 4.8 with the 6hp26 transmission. Ytd, I did a fluid change at 56k miles. I switched out the pan and changed the megatronic sleeves and adapter. After everything was put back together, I started to pump fresh fluid into the fill hole. Strange because at approx 2.5 qts it started to stream out already, I even pulled the Jack so the car was leveled. Anyhow, I put the plug back on and started the car but I didn’t shift gears. I turned it off and went back underneath and was able to put in another 2qts before it started to stream out again. I plugged it and started the car again shifting gears this times. I kept it idling and went back underneath to fill in more fluid when temps reached above 30 Celsius. I ended up putting in another 3qts before it started to stream out again. I plugged it and was done. Last step I did was pour the old oil back into the empty containers. Here’s what I don’t understand, the old oil came to around 6qts but I was able to put in 7.5qts of new fluid. So did I over fill the box? Or was I short a qt in a half from the start? I bought the car at 49k miles so I don’t expect the the fluid to have been changed. The old pan was a zf pan so I would assume it’s original from the factory. I’m just afraid I’ve got too much fluid in the trans. Any thoughts on this anyone?

I wouldn't be concerned. It's pretty hard to overfill the transmission. Either your transmission was a little low on fluid, or perhaps you spilled more than you thought in removing the pan?

AM.

Here’s the strange part, the pan is bolted back on and torqued down to spec, but this morning, I found a small puddle of trans fluid on the ground. It seems to have dripped in front of the pan facing the front of the car. The pan is dry though so where is it leaking out of? I do remember remember reading about the 6hp26 having a purge valve or something when it’s overfilled. I wonder could this be the reason.

Not much help, but some thoughts...


Any chance you had a leak all along, and thats why you see the new fluid on the floor? And why it was 1.5Q down? Unlikely for sure.


Possibly you just had some fluid on a cross member perhaps? Overnight it just made its way down....



Was the car perfectly level?

The ZF procedure has you 'let it drip' to get the fluid down to the right level. I wonder if you stuff in a bunch, then capped it- might explain why more went in.


Agree w AM that a bit more fluid isnt a big issue. Although 1.5Q seems like a bunch. Could a bit of unlevel, with maybe not enough drain time cause that? Dunno.



Ive never heard of a purge valve.


Did you use a BMW pan? ZF pan? I have not heard of this, but a variation in the pan shape COULD change the capacity. Just a few mm deeper could add up over the whole area of a pan.


Anyway, GL.