Tranny leak that keeps getting worse

[MJwrabbit]

I have a 1971. Its a numbers matching car. Upon advice from a trusted friend/mechanic bought a 200R4 for two reasons. One, to eliminate the leak issue and Two to have overdrive in the car. Yes, I still have the original tranny. Long story short, I still have the leak issue and its worse than ever. Brought it to a new tranny guy and he said I need a part 8678940. Of course its discontinued. I have been dealing with the new leak issue for the past two years and I am at my wits end. I would really like to drive my car. Can anyone please help me?

 

[mallard]

Just to make sure I'm understanding your plight correctly, your car's born with trans leaks, you replaced it with a 200R4 trans that also leaks? Talk about Deja vu all over again. Anyway, visually, where does it appear to be leaking from? Pan? linkage? or what have you?

 

[MJwrabbit]

There are two large wet spots on the floor forward and back. Tranny guy said its not the pan. I thought it was the seals but he said I need the part listed above. I googled it and cant find anything.

 

[xten]

How bout lines? Same ones? Oh, welcome back BTW. lol. Do you have the inspection cover on? Only reason I ask is I had a 700 R4 without the cover on and I had a split line forward from the fitting. Torque converter spinning and driving the truck blowing the fluid around and toward the rear made it very hard to find.

 

[Zspoiler]

You need to put it up on a lift to see where its leaking while running .Then go from there

 

[Bandit723]

There are two large wet spots on the floor forward and back. Tranny guy said its not the pan. I thought it was the seals but he said I need the part listed above. I googled it and cant find anything.

so what is the part? a linkage seal?

 

[biker]

This is a link to the part number, it is a linkage seal, and is discontinued. A trans shop will have an aftermarket supplier.
https://www.gmpartsgiant.com/parts/gm-shaft-rem-8678940.html

 

[tom3]

I'm guessing it's the seal on this shaft? But as mentioned above you need to get under there, spray it down with some cleaner, take a low speed cruise, see where it's actually coming from.


8678940
SHAFT, Transmission Throttle Valve, SHAFT, MANUAL-W/SEAL (INCLUDE 701)

 

[xten]

I have also seen trannies leak when a car sits a long time. Seems like maybe the converter drains back into pan and overfills it. then all kinds of things leak. I have a friend with a C6 and he puts a baster pan under it when he's done driving the car in the fall. It leaks, he strains it, puts it back in in the spring, doesn't leak while he's using it.

 

[Syklops75]

I had an issue once with a leak happening over days after I drove the car.. One was the seal you are talking about. Turned out someone had installed a second seal over the original without realizing it. The other was more difficult to find. It ended up being the driveshaft yoke missing the center seal inside. just a thought. It took forever to figure out.