Fluid out top of 350 AT dipstick??

[72CampSpecial]

Yesterday I drove the truck to the store after letting it warm up for 5 min, nice easy drive about a mile away..when i got there i had smoke coming from the passengers side, popped the hood and saw evidence of fluid on the top of the passenger header and wheel well..

Drove it home and no smoke, i peeked underneath the truck this morning and notice evidence of fluid on everything from on top of the starter down the back side of the engine, and passenger side of the trani, the lines, etc. Fluid in my drip pan this AM is red.. so pretty sure its a trani leak vice a oil leak.

Ive read that there was a problem with the dipsticks and fluid coming out the top??

My truck is a '72 Chev w/350 V8 and 350 AT, ive replaced the trani pan seal and the accumulator cover O'Ring on the side of the trani on the passenger side

What else should i be looking at??
Should i order a new (later model) Dipstick with the "locking" feature ive read about?? Anyone know where i can get that late model dipstick, or a part #??

[bronze 72 super]

The locking dipstick is for 700 r4 transmissions. These are the overdrive transmissions. They build up more internal pressure than a th350 or th400. You might have a plugged vent tube. Check this first. If not that, than have a transmission shop check for internal problems. Something inside is building up pressure and blowing fluid out the dipstick. Had the some thing happen on a th400 transmission. Internal problems. Hope this helps. Mike.

[72CampSpecial]

Thanks, where might the Vent tube be located on a 350 AT?

Or a good link to a illustrated parts breakdown?

appreciate the help..

['69C-10]

I'm having that same issue with a th400. Enough ATF out of the dipstick tube to fill the airgap intake valley. I have yet to find or get a solid answer on what causes this. Someone recommended the locking dipstick, but that seems like a bandaid to an internal problem.

[Boog]

The vent on a T350 is a small plastic tube on the very top of the tranny case. Usually dirt and grime buildup in it.
Tranny fluid will burn on a hot exhaust manifold so keep that in mind.

[72CampSpecial]

Originally Posted by Boog

The vent on a T350 is a small plastic tube on the very top of the tranny case. Usually dirt and grime buildup in it.
Tranny fluid will burn on a hot exhaust manifold so keep that in mind.

Is it a white tube about an inch long with a "floating cap" on it.. just pulled this from the near the top of the trani on the drivers side... covered in grime, cleaned it up and now the "floating cap" now moves and it is clear of debri..

is there another vent im looking for?

[bronze 72 super]

You found the right tube. Also check to see that there are no bent tranny lines, also a bad vacuum modulator might cause this. How is your radiator? A dirty or clogged up radiator might cause this too. Also over filling the transmission will do this. When was the last time you changed the filter? Use a good brand name filter like, Fram, Wix, something like that. Spend the extra money on a good brand. Asked my brother about this and this is what he said to check. Line pressure can be up to 250 p.s.i. Hope this helps. A th400 tube is on the right side, right above the vacuum modulator.

[72CampSpecial]

So I cleaned the white vent tube (pictured here above).. it was caked in grime/dirt..and wiped everything down that was wet.. took the truck for a drive (didnt hammer on the gas or do anything to aggressive, just normal speed up/down stuff) and all seems to be in order. I went a couple of miles down the road, stopped a few times and checked the Trani Dipstick and it was staying down (which it wasnt doing before all this happened), seems to shift good and no issues..

Im going to check the other things that where also suggested too... but hopefully it was just the clogged vent tube..

Thanks everyone for all the help..

fingers crossed...

[68K30]

ANY water in the trans pan will cause this, it lays on the bottom of the pan ( below the fluid) and during hard acceleration will boil and push the fluid and the dipstick out of the tube. The locking dipstick was used to prevent underhood fires from hot ATF spraying on hot engine components.

[72CampSpecial]

Originally Posted by 68K30

ANY water in the trans pan will cause this, it lays on the bottom of the pan ( below the fluid) and during hard acceleration will boil and push the fluid and the dipstick out of the tube. The locking dipstick was used to prevent underhood fires from hot ATF spraying on hot engine components.

68K30...i changed the pan gasket and filter about a month ago and replaced it with fresh fluid.. hopefully its still good..

[68K30]

A bad trans cooler in the radiator can also be the source of water in the trans pan.
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[RPBurris]

I had an issue where the plastic kick down cable casing was cracked and trans fluid would shoot out of there and make a mess. Like someone else said already though a hole in your trans fluid cooler or lines can spray just enough to make it hard to find.