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Topic: MYSTERY LEAK

in Forum: C3 Driveline Components


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MYSTERY LEAK (1/13)
 5/14/08 11:59am
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DUNEDIN, FL - USA

Vette(s):
1969 COUPE CORTEZ SILVER, BRIGHT BLUE INTERIOR 383 cu. in. 512 HP. Hooker headers w/ side pipes PS PS AC AM FM STEREO. 68,000.MILES C5 5oth Anniversary Coupe , auto.350hp


Joined: 10/22/2004
Posts: 832

SOMEBODY PLEASE SHED SOME LIGHT ON THIS. I`VE BEEN DEALING WITH THIS MYSTERY AUTO TRANSMISSION LEAK FOR 2 YEARS NOW. HERE`S THE STORY... T400 HAS BEEN COMPLETELY RE-BUILT , NEW OVER SIZE PAN,SHIFT KIT, NEW MODULATOR, GASKETS ,FILTER, NEW SPEEDO HOUSING, NEW FILLER TUBE AND 0-RINGS, ETC... IF THE CAR SITS FOR AN EXTENDED PERIOD OF TIME WITH OUT BEING DRIVEN OR STARTED.. ROUGHLY 2 WEEKS OR MORE, I FIND A RIVER  OF TRANNY FLUID ON THE FLOOR UNDER THE CAR. IF I DRIVE THE CAR REGULARLY... IT DOESN`T LEAK A DROP.  I HAVE HAD THE MAIN SEALS REPLACED TWICE( THINKING THEY MIGHT BE FAULTY) ALSO CHANGED THE PAN GASKET TWICE. TIGHTENED THE PAN BOLTS YADA YADA YADA... i STILL HAVE THE PROBLEM. ANYONE EVER EXPERIENCE THIS OR HEARD OF THIS. IT`S DRIVING ME NUTSConfused. I HAVE NOT SKIMMPED IN ANYWAY WHEN REPLACING THINGS.. MAYBE I MISSED SOMETHING HERE!

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MYSTERY LEAK (2/13)
 5/14/08 12:05pm
dwright
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Victor, NY - USA

Vette(s):
2004 Commemorative Edition Coupe, Auto w/HUD. 13K miles in 2015. Sold 1982 Red Coupe


Joined: 7/12/2004
Posts: 6833

With that much fluid, can't you tell where it originates from?

Sounds like a seal is shrinking when sitting.

 
Of course the solution is simple.
 
Drive it every day. Don't let it sit.LOL


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MYSTERY LEAK (3/13)
 5/14/08 12:12pm
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DUNEDIN, FL - USA

Vette(s):
1969 COUPE CORTEZ SILVER, BRIGHT BLUE INTERIOR 383 cu. in. 512 HP. Hooker headers w/ side pipes PS PS AC AM FM STEREO. 68,000.MILES C5 5oth Anniversary Coupe , auto.350hp


Joined: 10/22/2004
Posts: 832

DAVE,  I HAVE INSPECTED IT AND THAT IS WHY I CHANGE THE PAN GASKETS. I EVEN SUSPECTED THE DRAIN PLUG, EVERYTHING HAS BEEN REPACED WITH NEW MORE THAN ONCE AS FAR AS SEALS GO.
 
 UNFORTUNATELY , A DAILY DRIVER IT IS NOT. AT $3.92 A GALLON AND 6-8 MPG  IT`S NOT FEASIBLE.
MYSTERY LEAK (4/13)
 5/14/08 12:40pm
dwright
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Victor, NY - USA

Vette(s):
2004 Commemorative Edition Coupe, Auto w/HUD. 13K miles in 2015. Sold 1982 Red Coupe


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Are there cables that enter on the sides? Have those seals been replaced?
 
I have an auto.  I had a leak at the speedo cable and another leak at the kickdown cable. Replaced the seals and the leaks stopped.


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MYSTERY LEAK (5/13)
 5/14/08 1:03pm
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DUNEDIN, FL - USA

Vette(s):
1969 COUPE CORTEZ SILVER, BRIGHT BLUE INTERIOR 383 cu. in. 512 HP. Hooker headers w/ side pipes PS PS AC AM FM STEREO. 68,000.MILES C5 5oth Anniversary Coupe , auto.350hp


Joined: 10/22/2004
Posts: 832

from what i can see and from the origin of the fluid on the ground,  it appears the leak generates from the right side(passenger) of the tranny.
 there are coolant lines that connect there and I have not replaced those.is this a possible source? And  would it not leak all the time if it was?
MYSTERY LEAK (6/13)
 5/14/08 1:04pm
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DUNEDIN, FL - USA

Vette(s):
1969 COUPE CORTEZ SILVER, BRIGHT BLUE INTERIOR 383 cu. in. 512 HP. Hooker headers w/ side pipes PS PS AC AM FM STEREO. 68,000.MILES C5 5oth Anniversary Coupe , auto.350hp


Joined: 10/22/2004
Posts: 832

thanks Dave, however, that has already been done.
MYSTERY LEAK (7/13)
 5/14/08 1:04pm
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas


Joined: 11/8/2003
Posts: 20126

Here's the most likely culprit....the o-ring around the pump. Doesn't matter if it's been replaced or not, unless it has been replaced with a specific o-ring. I use one from a 700 pump, as they are a bit thicker, and seal mooch better...never had one leak with this set-up.
Here's what's happening...after sitting, the fluid in the torque converter drains back into the pan, raising the fluid level in the pan. When the level gets up above the lower edge of the pump, it will seep out around the pump o-ring, and it may appear that the pan is leaking.
The only solution for this particular issue is to replace the pump o-ring with one that is thicker, and it just happens that a 700 o-ring fits the bill. (Of course...some Bubbas seem to think that two complete tubes of sillycone around the pump will fix it...)
Now, for a dis-claimer.... This will only be the problem if you are 100% absotutely sure it is not leaking anywhere else, and it ONLY leaks after sitting for a few days.
For some reason, the 400 trans is really bad about this.
hth


We posted at the same time, so I didn't see the newest info! The cooler lines MAY be leaking, but you're correct in thinking they would also leak while running...not while just sitting.
If the pump is leaking, then with the engine running, it will "sling" the fluid over towards the pass side, and make it appear to be leaking there...Adams' Apple2008-05-14 10:08:08

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MYSTERY LEAK (8/13)
 5/14/08 1:10pm
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DUNEDIN, FL - USA

Vette(s):
1969 COUPE CORTEZ SILVER, BRIGHT BLUE INTERIOR 383 cu. in. 512 HP. Hooker headers w/ side pipes PS PS AC AM FM STEREO. 68,000.MILES C5 5oth Anniversary Coupe , auto.350hp


Joined: 10/22/2004
Posts: 832

joel, i have definately determined that all obvious leaks have been fixed. it only leaks after the vehicle has been sittng for a period of time. this is the best explanation I have had yet. i am going to re place the o ring and see if it solve the issue. can i get to that just by draining the fluid and dropping the pan?   Thank you, for you expert opinion

VETTERBOB2008-05-14 10:14:43
MYSTERY LEAK (9/13)
 5/14/08 3:31pm
Aaron1976
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Vancouver, WA - USA

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1976 Corvette Stingray L-48 Automatic Black


Joined: 11/17/2007
Posts: 830

I had my gaskets and O rings replaced recently on my '76 at Cottman's Transmissions. I was told the gasket around the shift linkage going into the tranny and the cable O rings are known to leak on these transmissions. So far I have not seen a leak but before I had them replaced I had the same issue.Big%20smile

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MYSTERY LEAK (10/13)
 5/14/08 9:25pm
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas


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Bob, unfortunately, the o-ring fits around the outside of the pump. No way to get to it without removing the trans, and the pump...
Also, if the trans has had a "shift kit" installed at any time, or has otherwise had other work done to it, the pressure regulator valve, and/or the pump may have been "modified", which leads to increased converter drain-back, which in turn increases the chance of the pump leaking after sitting for a few days, or in some cases, overnight!

Aaron, the 400 doesn't have a cable going into it like the 350 or 700 does. The shifter shaft seal will leak, tho, same as any of them.Adams' Apple2008-05-15 10:07:06

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MYSTERY LEAK (11/13)
 5/15/08 10:33am
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DUNEDIN, FL - USA

Vette(s):
1969 COUPE CORTEZ SILVER, BRIGHT BLUE INTERIOR 383 cu. in. 512 HP. Hooker headers w/ side pipes PS PS AC AM FM STEREO. 68,000.MILES C5 5oth Anniversary Coupe , auto.350hp


Joined: 10/22/2004
Posts: 832

THANKS JOEL,  LOOKS LIKE I`LL BE DIGGING INTO MY POCKETS AGAIN, Cool
I`M WEARING SUNGLASSES TO COVER THE Ouch. LOL I LOVE THIS CAR.
MYSTERY LEAK (12/13)
 5/15/08 3:17pm
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Mounds View, MN - USA

Vette(s):
70 LT1 coupe, 69 350 HP coupe, 69 390HP 427 coupe, 71 LS5 convert, 85 coupe, 93 coupe


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Joel is probably right, but there is one faint possibility to check first.  Sometimes the seal on the shift shaft leaks after sitting.  Clean it up and watch for it to get wet again.  If it doesn't, and it probably won't, then you are back to Joel's bad news.

Larry
MYSTERY LEAK (13/13)
 5/15/08 9:36pm
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas


Joined: 11/8/2003
Posts: 20126

The shifter seal had been mentioned by several folks, myself included, but...that seal would have to be missing completely to leak that much fluid over a period of a couple of weeks or so. Also, a leak in that position is really easy to identify, as it is really the only thing on the driver side of the trans that could leak, other than the pan.
It is possible too that there is a small crack in the case...not a real common issue, but it does happen.
Bob has replaced everything externally I can think of that would create a leak such as this...I hafta think it is a pump o-ring, or pump bolts leaking.

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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

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