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Transmission Leak on my 80

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BigBrakeFuelie

Guest
Hey I purchased an 80 Vette back in June and I really love it but it`s drivin me crazy with so many different leaks. I understand sometimes your gonna have them but one thing that I don`t like is a Transmission leak.
I`ve already replaced the powersteering pump,control valve,also had an exhaust leak and I replaced the manifolds.
New radiator,heater hoses etc. that`s all good but the transmission has leaked for the last two months and I fixed the leak at the speedo seal but then my upper tranny hose going to the radiator blew. I fixed that ,replaced the lower hose also for prevention.
I`ve had my tranny inspected by two different Tranny shops and they say it`s alright but my ? is why would my transmission keep leaking from one spot or another . Is it because my transmission is shot or what? could use some advice.
 
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billybob

Guest
BigBrake,

I myself had similar problems with my 75, mostly due to the age of the parts (gaskets hoses etc).

You may have an overfilled tranny, which is causing to much pressure on the old parts.

I used to have the recommended pressure rating for C3's around here will try and locate it. You can check it by putting a guage in between on of the rad/tranny hoses.

On a side note I replaced all my rubber with steel lines as they kept leeking at the metal to rubber joins no matter how hard I tightened the clamps.

Bill
 
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billybob

Guest
Also it may be a a faulty torque converter.

It's the mechanism that couples the engine’s rotational force to an automatic transmission.

Also on a standard its performed by the clutch.

Instead of transmitting the power via direct contact friction as a clutch does, the torque converter transmits power from the engine to the transmission by the force of oil flow.

Bill
 
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BigBrakeFuelie

Guest
Billybob- thanks for the info. I appreciate it. I might look into replacing my rubber lines for steel ones.
It`s been about a weak since my tranny hose blew and it totally caked the engine department including contaminating my right front brakes. I`ve driven it about 65 miles since I fixed it.
Do you think this current leak could be residual? I hope it is but I doubt it.
 
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billybob

Guest
Replacing with steel is actually pretty cheap,

5' 3/8" tube should run you about 5$ (marked gas line tube) bender about 12$ a cutter 6$ and the couplings (for joining tube to tube) 3$ a set I havent had a leak from the engine compartment since I did it that way.

I say 5' or 4' but you can use both natural ends to connect directly to the radiator and the couplings to connect to the exsisting steel lines. The line from the top will require some interesting bending but should be easy if you pretty much copy the pattern from the rubber line.

You'll need the cutter to snip the flared ends of the other sides as they have been enlarged for rubber connections attached the coupling on them aswell.

Screw them together and have no more leaks.

As for residual, its possible, the only real way is to get yourself an engine shampoo and clean it up, drive it around (switch gears including reverse, all while under load aka moving the car) then check for leaks.

Is it auto or manual, as I can specialize towards your transmission.

Bill
 
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BigBrakeFuelie

Guest
It`s auto, one of the leaks is coming from right under the lower transmission hose but I haven`t been able to detect a leak from the hose for sure yet.but unless it is residual it looks like that`s the problem.
Other leaks actually just discovered today are right under the engine towards the left a little. Might be the powersteering control valve again.
thanks
 
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billybob

Guest
Check the connection to the rad itself, it may be cracked as they are parts generally overlooked by most tranny shops.

The brass fitting could have been damaged of you may have flexed the connection during hose replacement.

Have you had a chance to put it up on the jacks yet to crawl underneath it? When in doubt get dirty and carry alot of cleaning rags.

On a side note dont overlook the pressure in the system, your torque convertor my be in need of some assistance, best left up to a professional unless you know what your really doing.

Personally I would take it back shop and get them to tell you the desired pressure and have em test it that way, there are numerous reasons for too much pressure but I have listed the most common 2.

Bill
 

cntrhub

Well-known member
Joined
Jun 17, 2002
Messages
390
Location
North Hollywood, Ca.
Corvette
Miss my '62 & '80 4- Sp. Vettes
You don't have to wash down the whole Trans to check for a leak. Take some brake cleaner/contact cleaner, and spray clean the hose lines and case area, you think are causing the leak? This area should now be spotlessly clean. Take the car for a short drive. Did you see a fresh run of oil come out of these fittings? Is it coming out of the case, where the female fitting are located? Clean the shift select arm seal the same way. Look for seepage.
Most residual oil will fall within a few hours. If you drove 65 miles plus, the heat, wind and time, will eventually stop dripping.
Find a large cardboard panel, draw a line down the center, and place it under the Trans. You should do this immediately after parking the car. Reference point the cardboard as to where it sits under the car. Pull the cardboard out within the first hour. If you judged right, the line drawn should have been in the center of the car. Is the leak to the left or the right of the center line? Is it forward or more to the rear? This will help pinpoint the leak. Look for seals, hose fittings on the outside. If the leak is more to front of center, it is most likely the torque converter seal or the large o-ring to the pump cover. If it is to the rear and center, it might be the tail seal, where the drive shaft yoke is.
A leak my travel to the rear, and drip down from the top of the Trans housing. Make sure the color is red/maroon in color. Don't let an upper engine oil leak throw you off.
 
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vmrod

Guest
Perhaps the front tranny oil seal? There is a dust cover on the bell housing (right behind the oil pan). There's a small hole in the bottom of it. Does it look like your leak is around there? If so, that could indicate an old front tranny seal.
 
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BigBrakeFuelie

Guest
Hey fellas- thanks for the input. I crawled under and and got to the lower tranny hose and adjusted and moved the clamps.Then I drove it about 5 miles and it`s not leaking so I think I did the trick.I will look in to getting those steel lines instead of rubber.Believe me a leak like that sucks, it will blow all over your engine compartment,soak the right side brake pads, even caked the ride side of the body.Ofcourse it didn`t help that I was driving about 90mph when the hose originally blew.
 
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billybob

Guest
BBF,

Glad to hear you you have it sorted out, leaks suck especially when you start adding chrome :)

Bill
 

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