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Yep just went a round or 2 with a Trans leak.
I can say with almost certainty your selector shaft seal is leaking.
PO probably overtorqued the pan bolts on that corner,causing them to strip out. Thinking the leak was coming from that corner of the pan.
Pan does not need to be off to replace the seal. Be careful when you put the seal over the shaft. the rubber on the seal is easy to cut on the flats of the shaft. My trick is to put 1 wrap of permacel(ptfe) tape over the shaft when installing the seal.
Once I get my lathe up and running I'm going to make some bullets that seals will slip over
It's a whole lot easier to remove the old seal and install the new one with the pan off and the selector shaft removed IMO. With the cramped quarters in a C3, I can't imagine getting that seal out and in with the shaft in place without a LOT of swearing.
AzMotorhead … I hear you but I’ve never had any indications, fluid or dripping from selector area but will keep your info. handy should I need it. Here's a pic after I just got back from a half-hour drive. The shift selector area hasn't been cleaned since I installed engine & tranny, in early July. Just no indication that it has been leaking.
What I did prior to test drive is I ended up re-tap'ing that hole that the helicoil was in to 7/16 and then used a 7/16" bolt with washer. Had to ream out the pan hole just a little. I also worked on repairing that pan bolt hole as it's top surface was deformed. I worked on trying to straighten the right front of pan which looked like it was bent down slightly. As mention I just got back from a test drive after first warming up engine & tranny and topping off fluid. Now I'll wait and see what happens. As mentioned before, if this doesn't do it for sealing the pan, then a new pan is in order.
ezobens ... you were right ... that stud that looked bent ... whoever drilled it out didn't get it straight so that's why I took your suggest of re-drilling straight & re-tapping ... 7/16" was the next size.
It's a whole lot easier to remove the old seal and install the new one with the pan off and the selector shaft removed IMO. With the cramped quarters in a C3, I can't imagine getting that seal out and in with the shaft in place without a LOT of swearing.
Ezobens. I just did this on a all stock 1980 took me all of 15 min to do it once the car was in the air. With simple combination wrenches and the tool. Removal is a snap. Once new seal is placed over the shaft use the other part of the tool (Tube looking piece). Use a long drift to get on other side of the exhaust pipe and tap the seal into place. It doesn't take alot of force to seat the seal and the drift doesn't have to be perfectly in line with the tool. The tool will ensure seal is drives straight
Ezobens. I just did this on a all stock 1980 took me all of 15 min to do it once the car was in the air. With simple combination wrenches and the tool. Removal is a snap. Once new seal is placed over the shaft use the other part of the tool (Tube looking piece). Use a long drift to get on other side of the exhaust pipe and tap the seal into place. It doesn't take alot of force to seat the seal and the drift doesn't have to be perfectly in line with the tool. The tool will ensure seal is drives straight
Do you have a picture of this tool? I've never seen one.
I've been killing myself for years replacing these manually-
I learn something every day!
Thanks!
I'll put $100 on a shift selector shaft seal leaking.
Anyone want any of that action?
When I started reading this thread, I thought that was most likely the problem as I have the same problem. It was the only seal that I didn't replace when I rebuilt mine, just overlooked it.
Looks like the leak(s) is/are fixed finally ... replacing the helicoil with bolt tapped to next larger size and reworking the right front corner of pan did the trick. Breathing a sigh of relieve of not having to pull the tranny. I guess if the converter seal was leaking it may have cured itself with getting some miles on it ... as it did sit for awhile during engine rebuild etc..
Thanks again for all the insight and tips. Now maybe I can get the car finished.
The TH400 in my '74 has a leak. It appears to be coming from behind the Torque Converter. Fluid leaks from the hole in the inspection cover and also from the driver side front of transmission. I don’t know if my garage floor isn’t level or the car but the bottom of the transmission pan is slightly lower on the driver side which I think is why I have a leak from that side on the front of tranny. I’m guessing if it’s the front seal to the transmission pump (behind the torque converter), that will mean removing the transmission to fix it. Are there any other things I can check first or any tests to prove for sure that it’s the front pump seal before I pull the tranny? Thks
View of front driver side of TH400 with inspection cover removed.
Jcpstrat...
Terrific post with respect o your tranny leaks....Had the same problem with my 78 TH350....My question to you is how did add your arrow and comment on your photo...Just can't seem to get a handle with that process....
Your help would really appreciated....
mk's78
Mike
BTW..I had mine repaired at a local tranny place and has never leaked since....
My question to you is how did add your arrow and comment on your photo...Just can't seem to get a handle with that process....
Mike ... if I had known I was going to end up spending this much time on it I might have been better off doing what you did ... glad you got yours taken care of too.
On the arrows and text ... I have a old version of "Paintshop Pro, V6" that I use. It has tool options for preset shapes and text that I used to add these as a different layer to a picture and then I merge the layers & save it.
The old versions are available as a free download and although they don't claim they will work with the newer versions of Windows i.e. Windows 8.1, it works fine on mine system.
Do you have a picture of this tool? I've never seen one.
I've been killing myself for years replacing these manually-
I learn something every day!
Thanks!
Just wanted to echo what ezobens said above and supply some additional pics to help anyone else that needs to change this seal.
Since it was highly recommended to change this seal and my car was still in a good position to take care of this I went ahead and did it yesterday. I got both the seal and tool from my local Chevy dealer and NAPA store. Neither had them in stock but had them for me the next day and for a total cost of less than $15, tax included.
Above pic shows half of tool. The arrow points to the threads (much like an Easy Out), that need to grab the inside of metal perimeter of seal that is in the tranny when the tool is turned clockwise. Tip: I had to wedge a Flat Blade between the transmission tunnel and the bolt on end of tool in order to get some pressure on tool so that it would go in far enough that it grabbed the seal correctly.
Above pic shows the old seal after it was extracted by turning the bolt on end of tool.
This is the new seal and the other half of tool that is used to seat the seal in tranny. Really slick!
Many thanks to everyone in this thread & all the info. & tips. Happy Vetting!
old threads are for research. i started reading thru it until i saw the dates. you-quite by accident- make people read through 30 some old posts to get to you and your issue which is completely different from the orig problem. we try to leave dead threads in the graveyard to avoid this confusion. click new thread. and a window opens to title it and write what you want to say.
Last edited by derekderek; May 31, 2021 at 08:44 AM.
