Tranny fluid pouring out of overflow tube when off

[huskerrush]

Hope someone can help me here... Have a c4 transmission behind a 351W in a 71 Sport Custom. After arriving home, turning the truck off, fluid began streaming out of the little tube on the side of the main tranny housing, just above and behind where the shift linkage connects to the tranny. I'm assuming this is an overflow tube.

So I let everything cool down, refill with type F fluid, and go for another short drive. Came to a couple of stops, put in Nuetral, got out and looked for any fluid coming out. None, not a drop. drove some more and again stopped, check for drips/runs in Nuetral and in Park. None, not a drop. I drove back home, parked in the driveway, turned the truck off, and the fluid come streaming out of the "overflow" tube, if that's what it really is.

My questions
1. What causes a transmission that has normal fluid level in it to send fluid out of the overflow tube?

2. If it's heat related, why doesn't it spill a drop until I turn the truck off, then come streaming out?

I appreciate all the help and knowledge you guys share here! Thanks.

[70shortwide]

bad o ring on the fill tube?

[TNIceWolf]

Well if its puking just when warm.....you might want to check out the possibility of a radiator gone bad internally. Dont forget that the tranny fluid circulates through it. and a crack in the crossover area of the two fluids could easily cause an over pressure in the tranny I would think. Of course if thats the case....your trans fluid should also be getting ready to turn a nice bubble bath foamy pink as well when checking the dipstick.
Just a thought....not a solution.

[huskerrush]

Well if its puking just when warm.....you might want to check out the possibility of a radiator gone bad internally. Dont forget that the tranny fluid circulates through it. and a crack in the crossover area of the two fluids could easily cause an over pressure in the tranny I would think. Of course if thats the case....your trans fluid should also be getting ready to turn a nice bubble bath foamy pink as well when checking the dipstick.
Just a thought....not a solution.

Good thought, however, the PO had replaced the radiator with one that doesn't route the transmission fluid through it, instead has a separate transmission cooler. I thought the fluid line between the transmission and it's cooler might be clogged, but the cooler was hot to touch, so I reasoned that hot transmission fluid is going through the cooler....

[70_F100]

Is it possible that you have the wrong dipstick and you're overfilling the transmission?

Had that happen once on a brand new van when I worked for GMC. Right tube, wrong dipstick installed on the assembly line.

[BobbyFord]

Sounds like the converter is draining back after shut off.

[huskerrush]

Sounds like the converter is draining back after shut off.

So if it's converter drain back after I turn the truck off, and it just started doing this three days ago, did some part break or seal fail? How do I check/test what has failed? Do I have to take the transmission out?

[Donnie]

After a few minutes of driving, enough to warm up the fluid, pull into your level spot, with the engine idling in park----check your fluid level
note where it is on the stick.........does it start dripping right now, in 10 minutes, or after a few hours...catch it in a pan, see if it is foamy
see how much accumulates & how fast....a few drops, a spoon full, or a lot........report back, someone will help you.....
The time lapse until the dripping starts info will be helpful, also the amount accumulated overnite,
other than this, does the trans show any other signs of impending failure ? shifts firm & on time?
Have you added chemicals to this unit?..........donnie
Some one already asked if it is overfull....wrong dipstick can be ruled out???? the cap on the dipstick is in it's correct notch?

[huskerrush]

finally got a chance to drive it today and record the observations. So I drove for a while, stopped, check the fluid level, all good. When I got back home, and parked in the driveway, got the pan ready to catch the fluid, stopwatch ready to time how long after turning off before the fluid starts draining out. None came out today. So I went for a longer drive, got nothing. I'm glad it didn't puke transmission fluid again, but I'm concerned now that the symptom is not repeating.

[vwfreak]

Sounds like the converter is draining back after shut off.

Doesn't the converter drain back after shut off? Isn't that why you check in park with motor warmed up and running?

[BobbyFord]

Sounds like the converter is draining back after shut off.

Doesn't the converter drain back after shut off? Isn't that why you check in park with motor warmed up and running?

No, the converter holds 8 quarts.

[Donnie]

...Yes what Bobby said is true, but a converter will only drainback if there is a worn part in the trans. that is letting air in ..Actually, I need to correct myself here a bit, any converter will drainback slowly over time if allowed to sit for LONG periods of time....But only 1/2 of the capacity will drain out, down to the hub, the lower 1/2 will continue to hold about 4 quarts..in the case of a large Ford converter.
Another note about converter fill & dipstick checking.........if any of you have now or have had in the past an earlier Chry product, you may have read the dipstick on 727's & 904 tranny's.....CHECK IN NEUTRAL, engine idling.........as the converter did not fill in park...This has been corrected in production on newer models & with some valve body kit's..........Donny

[vwfreak]

...Yes what Bobby said is true, but a converter will only drainback if there is a worn part in the trans. that is letting air in ..Actually, I need to correct myself here a bit, any converter will drainback slowly over time if allowed to sit for LONG periods of time....But only 1/2 of the capacity will drain out, down to the hub, the lower 1/2 will continue to hold about 4 quarts..in the case of a large Ford converter.
Another note about converter fill & dipstick checking.........if any of you have now or have had in the past an earlier Chry product, you may have read the dipstick on 727's & 904 tranny's.....CHECK IN NEUTRAL, engine idling.........as the converter did not fill in park...This has been corrected in production on newer models & with some valve body kit's..........Donny

Good to know Donnie and Bobby. I was thinking I had heard they drain. I have never heard mine drain but it IS a new unit from Hughes and the tranny is new rebuilt so maybe I shouldn't expect to.....

Sorry about the brief hijack!!!

Back to regularly scheduled programming:

[basketcase0302]

Good info to know for our slushboxes, thanks Bobby and Donnie.