Well, the other night I didn't do anything out of the ordinary, but I came out the next morning and there was about 1/2 quart of ATF (tranny fluid) on the ground, and its been sitting a week and has probably leaked another quart since then. I've been under there for hours trying to see where it's coming from, but the pan looks sealed pretty good still, and the front seal and pump don't look damaged either. Has anyone had this problem that might know what's wrong or where it could be leaking from?

[This message has been edited by FRDKILR (edited 05-12-2002).]

I'd check the dipstick tube. Since it's leaking heavily, this is an obvious area.

There is an O-ring on the tube that may have gone south.

I've seen (and have one) transmissions leak heavily if they sit for long periods but it sounds like your driving your car so that rules that out.

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Bob (Pa.)

1963 Impala 283
1966 Chevelle SS 409
1969 Malibu 307
1972 Malibu 307
1969 C10 stepside 350
1971 Cheyenne 20 3/4 ton
Somebody stop me... :)

Looking for Chevelle or Impala parts? Click here:
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When your car sits for extended periods, fluid drains back out of the torque convertor into the transmission case creating an overfill sort of condition.
Check the dipstick O ring (as previously suggested), the O ring on the modulator, O ring and seal on speedo driven gear, and seal on manual shift lever shaft.

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Well, I appretiate the info guys! Thanks a lot! If anyone else has any other suggestions just let me know!

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Bryce Gates
1972 Chevelle Malibu SS
350cid 4BBL HEI
TH350
3500 lbs.

TH350 leaking ATF??? Don't they all??? http://www.chevelles.com/forum/smile.gif

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Mike Newby

69 Chevelle 355/TH200-4R
97 Grand Prix GTP
64 Chevy C10 Pickup
79 Suzuki GS550

i had the exact same prob. drove to friend house and 2 hr later had bout 1-2q of tranny fluid on ground it was a wron/broken o-ring on the dipstick filler tube.

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72' Chevelle SS (Clone)
TC Member#1417

I also had the same problem. Turned out to be the o-ring on the kick down cable, it was pinched.

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66 chevelle thats in the middle of restification. 454 th350 12 bolt posi, global west rears, and more goodies in the rafters waiting to go on
Member #387

[This message has been edited by pop (edited 05-14-2002).]

That's it!!! It was the o-ring on the Kickdown Cable! Thanks for your help guys!

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Bryce Gates
1972 Chevelle Malibu SS
350cid 4BBL HEI
TH350
3500 lbs.

Thanks for posting the results...too many times people bring these mysteries to the board, and then we all never get to hear the results. The shifter shaft seal, kickdown cable o-ring, and dipstick tube seal and o-ring are common leaky areas on TH350s. Seems like there is an o-ring on the speedometer gear sleeve also.

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Mike Newby

69 Chevelle 355/TH200-4R
97 Grand Prix GTP
64 Chevy C10 Pickup
79 Suzuki GS550

Mike,
I'd like to add one more item to your list of leak culprits...those cheap, chrome, stamped steel tranny pans. Haven't seen one yet wouldn't leak. http://www.chevelles.com/forum/frown.gif

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Bill Burke
TC#613
ACES#3920
'68 Corvette L-79 coupe
'80 Camaro RS 355 Vortec


'68 Corvette L-79 (http://www.chevelles.com/showroom/68vette.jpg)
'80 Camaro RS (http://www.chevelles.com/showroom/Bills80CAMARO.JPG)

mine always leaked at the speedo cable and at the front seal and everywhere else. The speedo cable was the biggest culprit though. I would like to say that my new 700 R 4 doesn't leak at all (and it doesn't) but there is no fluid in there yet.

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65 Danube Blue MALIBU 4 door wagon, 350/330hp crate with 700R4, Factory air, Factory am/fm stereo.

Glad you found your culprit. Let me add one more thing that can leak on a TH350: There is an O ring around the front pump that can get pinched when being installed, and depending whether that pinch is on the top or the bottom can determine how much it leaks when sitting, but will constantly leak while driving. All this is according to my tranny guy who diagnosed my leak. Never saw it myself.

I'm with Georgia...it's possible to have a TH350 that DOESN'T leak??? http://www.chevelles.com/forum/smile.gif

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70 Impala Sport Coupe (350)
67 Chevelle (I wish, still looking and saving)
http://www.geocities.com/ledsled_26m

the one in my 84 elky doesnt leak...750$ later http://www.chevelles.com/forum/eek.gif