Topic: C4 Transmission Oil Pan Gasket

[ChrisV289]

What material was the original transmission oil pan gasket made out of?  Was it cork or other? 

[Bob Gaines]

What material was the original transmission oil pan gasket made out of?  Was it cork or other?

Cork is factory.

[J_Speegle]

Cork is factory.

+1 and can be more difficult to find since many suppliers have moved towards synthetic material instead

[ChrisV289]

Thanks Bob and Jeff.  I ordered a cork gasket from rock auto. I’ve read some people use a sealer as well and some say not to on cork. Thoughts? I just had it rebuilt and I assume they changed that seal but it is leaking from there.

[J_Speegle]

Thanks Bob and Jeff.  I ordered a cork gasket from rock auto. I’ve read some people use a sealer as well and some say not to on cork. Thoughts? I just had it rebuilt and I assume they changed that seal but it is leaking from there.

If you must use a sealant - used it on the inner edge of the lip so that it does not squeeze and and become visible

Also use something that will hold up to the tranny fluid and the fluid can always seep through the cork itself I've used Aviation Form a Gasket when I needed too.

Make sure you work the pan so the metal around the attaching holes are flat and don't overtighten

My tips - others may have their tricks

[Hipo giddyup]

+1 to Jeff's comments. I just did this like 3 times over a few months on my recent project. I used cork, a thin film of sealent, made sure the pan was flat (using a flat end hammer and a piece of wood to flatten the raised area where the bolts go through), and DO NOT over tighten! I feel the real key to success is torquing follow the Ford specs. Go the extra mile to keep the leaks from coming back. 

[Morsel]

Hey Chris,

Been through this and really battled it, went to all the forums and ask for suggestions and got some really good answers and technics used by transmission rebuilders on how to solve and seal a leaky pan. First of all you shouldn't need to use sealer unless it's absolutely as a last result. Then you should use an RTV gasket sealer, preferable grey so if you do get a little coming out that it matches the tranny and pan. But here's the method I used and posted on another forum, I had a rally bad leak that I couldn't get to stop and tired everything. I've used this method three times since then and it's been working. One thing is a lot of transmission rebuilders feel that the ford torque specs are too tight... Hope this helps.

"Ok, I've had nothing but trouble try to get my C4 pan to stop leaking. I've tried everything that's been suggested here and I couldn't get it to stop. But I finally did and thought I would share what I did to finally get it to stop.

I've tried six different times with different gaskets and methods suggested. My pan is original because my car is original. I've tried all different torques specs, tried lubelocker gaskets, cork gaskets of different qualities, synthetic gaskets, and different torque specs and by feel as others suggested. Nothing worked. And I didn't want to use RTV or any other silicones to stop it cause you shouldn't have to.

I tried again and bought another cork gasket. This one came and it was much different than any I had received previously. First, it was all real cork and didn't have that flimsy rubbery feel that the others I've received have, it was also a lot thicker than others and had no cutouts like the originals used. My pan is dead straight, of course this was taken care of after the second attempt with things I read, so that was never the issue.

Ok, for install, obviously I cleaned the hell out of everything as I always did using brake cleaner and made sure everything was dry. Installed the pan and made sure gasket was square (which of course I always did before). Hand tightened all the bolts as tight as I could.

Now, I've looked everywhere for people telling me actual torque specs, no one will list it. The ford shop manual says 12 - 16 foot pounds which everyone's says is just too tight, which I believe to be true as well from trying it before. 12 foot pounds is 144 inch pounds, a lot. Since I'm not good with feel, I wanted actual numbers.

Here's how I beat it, I torqued the bolts to 60 inch pounds in a crosscross pattern. I let it sit for 2 hours to sort of mold to the shape. Then I torqued it again to 95 inch pounds in a crisscross pattern again and let sit for 24 hours, again forming to the shape. Last thing, torqued them to 125 inch pounds in same crisscross pattern and watched the gasket for a slight bludge which it just started to do at each bolt. Again I let it sit for 24 hours before filling with fluid.

Filled it with fluid and it's been two week and no leaks, I finally got it.

So I thought I would share what worked for me because I know a lot of people suffer from this same thing and have trouble getting it under control.

Hope this helps others in the future.

Jason"

[NEFaurora]

Make sure that you get the right C4 Gasket if you have a '64 1/2 to '66 Green Dot Transmission.  The Correct Gasket should look exactly like the one below...with no "notches".  95% of the time people use the wrong gasket and wonder why the tranny pan starts leaking.  Most vendors sell the incorrect gasket as well for the Green Dot Tranny which is just a Generic '67-'70 C4 Gasket and it's incorrect and will leak.

This is the gasket that you need to use.. If yours looks any different, You've got the wrong gasket.  It almost a perfect rectangle will no notches.. Believe that in '67 that the Gasket was changed to the one with the notches in it...but the "Green Dot" C4 should have this one below...  Also, Sometimes this same correct Gasket will have small half round cut-out in the Corner with the big tab...but its the same gasket.  I think that I have a pic of one of those around too.. I'll try to get it up here as well.

See here:


I went out to my Garage, and I pulled the other C4 "Green Dot" Gasket and took a pic of it as well.  This is the other "Correct" type of "Green Dot" Tranny Gasket.  Note the difference in the Large Corner versus the 1st Correct type above.  To be honest, I have no idea of the significance of the bigger cut in the corner on the 2nd Gasket below...or if there is even a significance at all..  )  Tony K.