Turbo 400 leaking/blowing ATF out the top of the dipstick tube

[WinDancer]

My turbo 400 transmission, after being hot and filled to the hot mark on the dipstick, is now blowing Tfluid out of the Dipstick tube. The o-ring had been changed twice with no change. It is not leaking anywhere else.

If I take out 2 quarts it stops the spewing and engages the way it should, but is off the bottom end of the dipstick. That's not gonna work for me.

The tranny worked just fine until filled to the mark.

I filled it with the amount of quarts it called for when we swapped it to replace the 350 and had it out for cleaning and painting- it worked very well until the mechanic on Tuesday filled it to the mark on the dipstick.

Did Chevy build turbo 400 dipsticks in different lengths?
Are the 400 short-shaft 400s using a different length?
4x4s maybe?

Any knowledgeable help is disparately needed.

Who do I call or where do I find info on dip stick lengths for the turbo 400s?

TIA,

[sick69]

just out of curiousity,,,, do you actually have the 400 dipstick in it? did the 350 dipstick get switched with the 400?

I have 2 400s what did you need to know about the dipstick? measurements?
let me know i'll get measurements for you pics to if you need them


Frank

[WinDancer]

Sick69, was my first thought, too, that I had maybe switched them by mistake. So I went over to Classic Heartbeat and Wes pulled dipsticks from 3 different 400s and one 350- they are all the same length. The mechanic is gonna switch out the tube and dipstick for one of Wes's 400s and see it that makes a difference The tubes & sticks are at the mechanic's now and I haven't energy enough to run back up there again today.

Anyone else have any ideas or had this problem?

Thanks,

[john]

If I remember right the 400's have a vent tube right in top. Make sure its clear.

[burban70]

Had it happen to me and found out the filter was cracked and sucking air. Just a thought.

[Jayss109]

there is a vent tube, and they do get clogged with all sorts of things (paint, grease, crud whatnot) thats where I would check first

J

[1bad chevy]

Originally Posted by Jayss109

there is a vent tube, and they do get clogged with all sorts of things (paint, grease, crud whatnot) thats where I would check first

J

try this iv'e seen tranny's work fine run low weird as it sound's but i had a vent tube cause this problem it was a bee making a nest

[Scott Webster]

ditto on checking the vent tube - had a tranny blow a seal and it was blamed upon some bees making a home in the tube while it was parked for awhile.....

[WinDancer]

While no one has answered the direct question about different length dipsticks it appears they are the same and this dang vent tube may be the culprit.
Anyone have a pic of the vent tube so I can locate it?

As usual, thanks to all who took the time to answer.

I love this board!

[wibilly]

i belive the 4wd trucks with ac had a longer tube and stick

[Jayss109]

hard to see, but follow the braided trans line inbound...looks like a 1/4 moon tube. (Pass side top)

2nd is a th400 dipstick (out of a cadillac 1976)

[Texasbigblock]

itll be right on top of the tranny, just a small vent line about 3 inches long or so

[WinDancer]

Just talked with the mechanic again.
The 24" tube from Wes has been installed, but now the ATF doesn't show on the stick and is still blowing thru the dipstick tube.
The vent tube is clear and that is blowing a little AFT also.

The mechanic also said the only thing that made sense now was that the torque converter was somehow draining back into the tranny case and causing the over-full problem.

Said he was gonna talk to a couple tranny shops and see what they suggested.

Found several problems like this thru google but none had a fix.

I have heard nothing but great things about the turbo 400 ever since I can remember. Guess this is one small item for the other side.

Thanks for all the great suggestions and things to try. Will update this post after the problem is fixed [or the truck is stolen - just kidding] to have a record of the problem and the fix together.

[WinDancer]

Well, just ordered a new street-fighter TCI 400 from Summit- the tranny was toast.
Hope others have better luck

[1970 CST Short Wide]

Just curious! What prompted you to fill it? Was it acting up? Was it low and you just never checked it? What part was toast, did you figure WHY it was blowing oil.
It’s nice to know so if we ever run across this problem we can remember back to your post. Not trying to be a smart ass - just wanting to know.

Thanks

[68 Stepside]

I agree, I'd like more info if you have any. A friend of mine had a TH400 that puked out of the dipstick tube after it was run and shut down, and he tracked it down to a balooned torque converter.

[OLDIRON69]

The pump going south will do the same thing. Is this a fresh install? If so you may have needed to put some washers inbetween the torque converter and flexplated to keep the torque converter from walking back and fourth. It takes more pressure in reverse and can force the converter into the pump. Kind of hard to explain how it does this, but it has happened to me. I would pull a line off the TQ converter and see if you have fluid pumping thru. Normally when this happens you loose all gears at once...VERY quickly! Hope it is just the vent tube, and if so you can stick a paper clip or piece of wire in it to clear any debris blocking it. Good luck!