ATF coming out of shifter at high rpms

[TonyG2]

I got pulled over a few times at the dragstrip b/c my car was smoking. It was an ATF leak from the shifter area, that was dripping down on my exhaust. The tranny (T45) wasn't overfilled -the fluid level was just beneath the fill hole.

It wasn't coming out of the vent pipe either. I took the cover/boot off the shifter and watched it carefully:

1st gear nothing,
2nd gear nothing
3rd gear, past 5000 rpms, ATF fills up the well around the shaft area of the shifter (see arrow in photo) and starts overflowing out. It was like pouring water into a glass and letting it overflow. No fluid came out of the vent tube.

This only happens when I run the car hard, at wide open throttle.

One thought I had was that the vent tube was clogged, causing air to pressurize and push out the fluid through the shifter. So I removed and inspected the rubber vent tube, to look for a clog. There were no obstructions blocking the path of air. I blew into it and noticed that it does takes some effort to get the air to come out of it. But I think that's the way the tube is designed b/c the only way the air can leave the vent tube is thru a small triangular slit on the side of it.

I removed the shifter and looked inside the transmission. It looks normal to me:

Any ideas why this is happening?

 

[V6&V8SHO]

Don't know but my shifter started doing that and 3 months later the tranny blew up. This was the 3650 5 spd. POS. I now roll T56.

 

[V6&V8SHO]

Pic I took when it started spewing.

 

[TonyG2]

I have to blow pretty hard into the vent tube/breather to get air to blow out. I'm thinking about increasing the slits in the vent tube to let the tranny breather better.

Also, it seems like the vent tube only lets air out, not in (kinda like a check valve). Shouldn't the vent tube also let air into the tranny, so that the fluid that gets up into the shifter area can more easily drain back down into the tranny?

I'm tempted to yank the vent tube and replace it with a hose that runs uphill into some type of breather tank....but I'm not sure if this will cause some other type of problem.

 

[cobrob]

I had this problem so I put a aftermarket shifter on and never leaked ever since.

 

[TonyG2]

The shifter is aftermarket (MGW), but there are weep holes designed in it. If the shiifter cavity is filled with fluid and pressurized, the fluid will pass through. I verified this with MGW.

 

[Janstang]

Give D&D Performance a call 1-248-735-6220, see what they think it is..