Trailduster spewing trans fluid like Mt Vesuvius!

So I have been working on this 74 Trailduster. It has a 727 that was leaving like crazy from the pan gasket..or so I thought. I replaced the gasket, new filter etc...topped off the fluid. Fired it up and all looked good. No leaks. Then....I pulled it out of the garage, and was putting up by another building. When I stopped, smoke was rolling from under my hood. Popped it open, and there was trans fluid all over the engine. It looks like it was blasting up out of the trans dipstick tube. What the heck would cause this?
Dave in Colorado

How much fluid did you add after dropping the pan?

It was probably 5 quarts. Let it idle for a min and checked it and looked fine on the stick....

did you check it in neutral?

Yep....neutral.

Not uncommon for it to throw fluid out the vent and sometimes the dipstick if you add all the oil real quick.
I would just clean it up and monitor.

If not overfilled, it could be the vent is plugged.
Seen it on transmission converted to rear vent, and the vent tube got too close to header and melted venttube closed, then trans fluid blew out dipstick tube

You may want to pressure test the cooling system, and check for transmission fluid in the coolant.

Unlikely, but worth a look.

I had something similar happen way back in 1995. I had a 66 Fury that was my daily driver and it was constantly leaking transmission oil. I could never find the leak. So I said screw it and drove it, adding oil when it needed it. On my way home from work one day I could really smell ATF on the exhaust and I’m thinking WTH??? And then in an instant it looked like I was crop dusting. Fortunately I was 2 blocks from my house so I got it home. I pulled it into the alley so it didn’t drip oil all over the driveway or my shop floor and let it drip for a few hours. Once I wiped everything down so I could see what was going on, I found one of the cooler lines had split. Right in the seam. So that thing was leaking from that seam for a long time before it blew like a death aneurism. And it was impossible to figure out where the leak was coming from because the air under the car would coat the underside of the car with ATF so it looked like it leaked everywhere. Once I fixed that it was dry as a bone.

I am in no way questioning your knowledge and appreciate all the help you provide on this forum. But I am curious as to what would cause the above?
One can only put the fluid in as fast as gravity and the dipstick tube will allow unless of course one is somehow pressurizing the fluid and forcing it in. Even then I'm trying to understand what would cause it to burp the fluid unless of course as previously mentionned the vent in the pump suddenly became plugged which seems unlikely.
Again, thank you and Mr. Kunkle for all the help you both provide

I had something similar when I bought the '65 Satellite. I was taking it apart for restoration - and I found the trans cooler lines were routed wrong by a prior owner. One of the trans cooler lines was rubbing against a chassis part and was worn razor thin. Must've been that way for years.
- Art

Assuming you added the fluid when they trans was cold - thermal expansion and fluids being slung around during fill can cause the vent or dipstick to leak.
The dipstick tube is downwind from rotating parts so that can add to the issue.

Depending how long the pan was off, the converter drains a tad as well. Expelling fluid/air from the converter adds to the issue.

“In plant” fill at the assembly plants had us doing a step fill. To prevent false leaks.

This is all great information. I am going to run it again tomorrow after work and just watch things. I will update when I know where the source is...

Hmm, never heard or experienced it, thanks for the response

hello,
at one time race car would shoot fluid out dipstick tube when shut off. was never able to fix, converter, valve body change etc. cracked case ??? heat sink cooler mounted on firewall above tranny air bond??? ended up changing tranny

Would have more questions but since the trans has been replaced I guess all we could do now is guess.

Best guess, a real rapid increase in heat buildup after shutdown expelling fluid out. Why? Dunno.

Great guess IMO, The why would be the fluid getting too hot which you stated and makes perfect sense, Only other thing i could think of is being overfilled due to the wrong dipstick/tube

i'm for thinking it would be the heat sink cooler on the firewall. horizontal in and out tubes [?] causing air in the system when the engine was shut off, and the fluid was suddenly dumped back into the transmission. however, since the transmission was changed, and it stopped, [still using the horizontal firewall mounted cooler ?] that throws out my thoughts, so ?
i realize factory coolers in front of the radiator are as high [?] but they usually have bottom in/out tubes.