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Topic: Tranny Leak !!!

in Forum: C3 Driveline Components


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Tranny Leak !!! (1/11)
 5/1/13 10:41pm
JC VETTE 70
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, - Canada

Vette(s):
70 VETTE 350/300HP, AUTOMATIC, ALL STOCK EXCEPT FOR MILD CAM,LAGUNA GREY, 3:55 POSI GEARS


Joined: 3/9/2008
Posts: 164

Took the car out of storage last week and found a puddle of tranny fluid. I had the tranny fluid, filter and gasket changed just before it went to storage last year. I had two small leaks last year so the mechanic dropped the pan inspected the surronding areas and it all looked good. We changed the gasket and it still had a small leak before it went to storage. Any ideas what is causing the leak? Everything above and surronding the pan looked dry at the time.

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Re: Tranny Leak !!! (2/11)
 5/2/13 7:19am
rod7515Lifetime Member
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Red Lion, PA - USA

Vette(s):
1974 White 350 Corvette, TH400 Automatic 1972 Tangerine /Go Mango Convertible 383 Stroker, 2004r Automatic


Joined: 10/27/2006
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Sounds like your going to have to get under it and see where the fluid is coming from. Main things I have seen on these are pan gasket which you have already changed, front seal, rear seal and the side seal. The worst one being the front seal because trans would have to come out to do. If its frt seal you usually have fluid hanging on the converter/flywheel cover. But a pan leak could also show up on cover as well. i would remove that cover, clean everything real good and drive it for a few miles. then look to see what is leaking. Side seals will leak down the trans and many people think its the pan because it comes down and drops from the edge of the pan. If that's your leak it can be fixed in the car but you'll need a special tool. I may still have mine if you need to borrow one. The rear seal you would have to pull driveshaft to replace but not a terrible job to do. Hope this helps, I'm sure more suggestions will come from this group. Best of luck. Rodney

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Re: Tranny Leak !!! (3/11)
 5/2/13 7:24am
Adams' AppleLifetime Member
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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
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Assuming it is a 400 trans, a couple of things...
The 400 has an issue with the o-ring that seals the outer diameter of the pump shrinking with age. If it sits for extended periods, the fluid will drain back out of the torque converter, raising the fluid level in the pan. The level will get high enough to be above where the o-ring seals the pump, and, with a shrunken o-ring, it will not seal, and fluid seeps out. It can run down the pan rails, appearing to leak from the pan. The only cure is to remove the trans, and replace the o-ring, and pump gasket.
It's also possible the trans pan is not flat where the gasket sits. Other leak areas include the shifter shaft seal, electrical connector, governor cover, modulator, and cooler lines.
I would suggest cleaning/drying the trans off well, driving a few miles, then check to see if you can determine where the fluid is leaking.


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Joel Adams
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Re: Tranny Leak !!! (4/11)
 5/2/13 1:01pm
RedwingvetteLifetime Member
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Waterford, MI - USA

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1973 Red coupe


Joined: 9/13/2002
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I had the same issue with my 73 TH400. If the car sat for more then a week the oil would leak out of the pan gasket. After many attempts at replacing the gaskets and seals I discovered the casting had lots of porosity in the pan seal flange. I finally fixed the problem by replacing the trans with the 200-4R OD.

Hope you get yours fixed soon.

 

 



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Brian - NCM Lifetime Member

73 coupe L48, Flat-top pistons, Performer RPM Heads, Crane Cam and roller rockers, Holley 650 vac sec. Performer intake,
3.55 gear BTO 200-4R trans,
Leather seats, Seatbelt Plus 3point seatbelts, Pioneer CD player
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Re: Tranny Leak !!! (5/11)
 5/3/13 7:53am
manchestersharkLifetime Member
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Equinunk, PA - USA

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1972 conv, 4-speed, 350, 200hp, numbers match, rally wheels, war bonnett yellow w/white top. good condition, nice driver.


Joined: 10/31/2007
Posts: 2382

 Check and or replace the speedometer gear "O" ring. Mine was bad, leaked. after replacement it was good.

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Re: Tranny Leak !!! (6/11)
 5/3/13 10:42am
rraider1
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Woodland, WA - USA

Vette(s):
1977 T-Top,350,Auto Black Ruby Pearl,Steeroids R&P conversion


Joined: 10/14/2003
Posts: 1165

I have had a similar problem and just changed out a chrome dip stick back to a stock one, which replaces the oring on the dip stick tube. I believe that is where mine was leaking from.
Re: Tranny Leak !!! (7/11)
 5/3/13 11:37am
dyoes
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Zachary, LA - USA

Vette(s):
1974 L-48 Auto. Just your basic Vette. GM crate motor w/vortec heads and intake. Crane cam. Scorpion rockers, Edelbrock carb. Lots of parts still in boxes... :(


Joined: 1/27/2013
Posts: 201

manchestershark said:  Check and or replace the speedometer gear "O" ring. Mine was bad, leaked. after replacement it was good.


That's where mine was leaking from.  If you change the o ring, inspect the speedo gear.  The little o ring is spring loaded, and if it's failed, the metal spring may have grooved the gear shaft.  If it's grooved up, replace it (it's cheap).  Be careful you don't drop the gear in the transmission when it's going back together, very easy to do!


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Re: Tranny Leak !!! (8/11)
 5/3/13 10:47pm
JC VETTE 70
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, - Canada

Vette(s):
70 VETTE 350/300HP, AUTOMATIC, ALL STOCK EXCEPT FOR MILD CAM,LAGUNA GREY, 3:55 POSI GEARS


Joined: 3/9/2008
Posts: 164

Re: Tranny Leak !!! (9/11)
 8/16/13 8:50am
dbarnesid
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Boise, ID - USA

Vette(s):
1972 mille miglia red corvette convertible. This is a car currently under restoration. The pic above is of me and my Ph.D. candidate daughter. She, not my Vette, is my pride and joy. Smile...


Joined: 5/29/2013
Posts: 159

Adams' Apple said: Assuming it is a 400 trans, a couple of things...
The 400 has an issue with the o-ring that seals the outer diameter of the pump shrinking with age. If it sits for extended periods, the fluid will drain back out of the torque converter, raising the fluid level in the pan. The level will get high enough to be above where the o-ring seals the pump, and, with a shrunken o-ring, it will not seal, and fluid seeps out. It can run down the pan rails, appearing to leak from the pan. The only cure is to remove the trans, and replace the o-ring, and pump gasket.
It's also possible the trans pan is not flat where the gasket sits. Other leak areas include the shifter shaft seal, electrical connector, governor cover, modulator, and cooler lines.
I would suggest cleaning/drying the trans off well, driving a few miles, then check to see if you can determine where the fluid is leaking.



It never ends with cars like mine that sat idle for five years. :) Mine has leaks from o ring seals, and just about every location mentioned except the pan. No leaks there. When the tyranny is dropped I could go ahead and have it rebuilt. Is that a good idea? If so, any suggestions? The tranny shifts smoothly but probably is completely original. Clunks when first put in gear but nothing more. My mechanic put trans x in it to seal the leaks. (Didn't work). Does that change anything?

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Re: Tranny Leak !!! (10/11)
 8/16/13 12:44pm
Adams' AppleLifetime Member
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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

dbarnesid said:1:When the tyranny is dropped I could go ahead and have it rebuilt. Is that a good idea?

2:My mechanic put trans x in it to seal the leaks. (Didn't work). Does that change anything?


You answered yer own first question with the 2nd statement..."My mechanic put trans x in it to seal the leaks"....
You really have no choice, now, but to have it rebuilt.
Putting something in a trans to stop it from leaking(other than new seals) is just silly, imho(NO disrespect to anyone who has, or will continue to do it). You might get the leak to slow down for a while, but it ain't gunna FIX it. That stuff works on the principal of swelling the rubber parts/seals, in hopes that the swelling will make a tighter seal. All that stuff really does is soften/swell the rubber parts....but then there's nothing to keep the seals from continuing to swell....right up until the point where they just fall apart....now you have a really BIG leak. LOL  And usually, a trans that no longer functions at all.....
I can tell when a trans has had some kind of seal swelling compound poured into it...I can smell it, for one, but it's the rubber stuff that is now 50 times larger than it should be that tells the tale. O-rings simply fall off of the components....they are now better suited for use as rubber bands than seals.
Ya need a more practical reason for never using that stuff? Well....you'll never be able to correct what should have been a MINOR repair after putting that stuff in the trans....the trans will ALWAYS have to be completely disassembled and rebuilt if it has some sort of miracle stop leak juice in it...


Otay...rant over....sorry......Embarrassed I shouldn't get so wound up over it...it's actually good for business.....LOL

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Joel Adams
C3VR Lifetime Member #56    

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Re: Tranny Leak !!! (11/11)
 8/16/13 3:42pm
dbarnesid
Former Member

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Boise, ID - USA

Vette(s):
1972 mille miglia red corvette convertible. This is a car currently under restoration. The pic above is of me and my Ph.D. candidate daughter. She, not my Vette, is my pride and joy. Smile...


Joined: 5/29/2013
Posts: 159

Well, I talked to the prior owner today. He said he put 1,000 miles on the car since 1992. Yup. 1992. So there's a strong chance that all of the seals are dried out. Right?
 
But the good news is he had the tranny out himself. (He builds dragsters so he likes doing stuff like that.) And he claims that all of the hard parts are good.
 
So, best case scenario is that we replace the seals and we go on our way. Expensive. But not as bad as if there are hard parts that need to be re-done. Other good news. The Trans X was put in the car two days ago. So I doubt that any of the seals have swelled out of control... yet.
 
Do you agree with the above or am I smoking some good stuff?
 
Edit: The tranny shop that specializes in GM said Trans X is the only such treatment they like. They said it won't cause harm and it won't even start to do much for at least 100 miles. They're not concerned so I'll sleep better now. Wink


|UPDATED|8/16/2013 12:42:31 PM (AZT)|/UPDATED|


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