Author Topic: C4 transmission pan leak (Read 7584 times)

Jeff1967 · « **on:** June 19, 2009, 06:44:45 PM »

OK,
I have tried a cork gasket, then a synthetic gasket without sealer and with sealer and no luck stopping the pan from leaking. I now have a new pan and have a new gasket on the way... I want opinions on how to proceed, The guy at NPD told me to ruff up the flange of the new pan with light sand paper to give the gasket something to grip to. Sounds like acceptable advice. Do I use sealant or try dry again?? I understand to torque to 12 lbs and the sequence to do so. IS THERE ANYTHING ELSE I AM MISSING?? I am tired of dealing with this problem and want to get it corrected....... HELP !!!!!! In addition the NPD guy recommended sealer around the bolt holes and corners, if this is what is advised I want to know specifically what brand and type of sealant to try???

Thanks in advance for all help !!!!!!!

Jeff

Soaring · « **Reply #1 on:** June 19, 2009, 07:29:37 PM »

Jeff, it's called black RTV, and you can get it at any auto parts stores. Slap that stuff on there with your rubber gaskets and torque down the bolts in the correct order and you will seal her from leaking.

Jeff1967 · « **Reply #2 on:** June 19, 2009, 07:45:42 PM »

Glen,

I am sure I need to let sit until tacky, do I apply to the pan side or transmission side or both?

JJ

Tim175 · « **Reply #3 on:** June 19, 2009, 11:59:17 PM »

I've always just used it on the pan side, around all the holes and its worked for me.

Soaring · « **Reply #4 on:** June 20, 2009, 12:11:05 AM »

Yeah, let her sit for an hour or so to get tacky. The pan side is preferable.

mustangluver · « **Reply #5 on:** August 26, 2009, 09:36:28 PM »

correct me if im wrong but isnt it normal for the c4 tranny to leak a bit? or is this fixable?

Soaring · « **Reply #6 on:** August 26, 2009, 09:46:25 PM »

You're wrong.

mustangluver · « **Reply #7 on:** August 27, 2009, 02:19:56 PM »

so why the hell does my manual say its fine. ill take a picture when i get a chance. of the pan i mean.

Soaring · « **Reply #8 on:** August 27, 2009, 03:36:04 PM »

Your manual was written by an idiot I guess. No pan is ever supposed to leak. That includes the oil and the tranny pan. The oil pan on my 65 is dry as a bone, and it has been on the car I know for over 20 years. The C4 pan leak can sometimes fool you. Check very carefully where the dipstick goes into the pan, and see if maybe that is where it is leaking. If so, you can replace that "0" ring to stop it.

mustangluver · « **Reply #9 on:** August 27, 2009, 05:45:02 PM »

when it was rebuilt wouldnt the "O" ring be replaced as well?

Soaring · « **Reply #10 on:** August 27, 2009, 06:40:22 PM »

It should have been. Just inspect it to make sure that is not where it is leaking. The instructions for replacing the pan gasket say to install it dry, but most of the time it will leak without some black RTV applied to the pan side.

mustangluver · « **Reply #11 on:** August 27, 2009, 07:09:34 PM »

i can just air dry it right? and my shop manual is fairly old

Soaring · « **Reply #12 on:** August 27, 2009, 07:23:57 PM »

Air dry what? The black RTV? Yup.

Jeff1967 · « **Reply #13 on:** August 27, 2009, 07:55:29 PM »

Let me tell you about battling a C4 pan leak first hand !! I resealed mine 5 different ways before I got it to quit leaking. I tried a synthetic gasket dry and then with sealant, cork dry and with sealant, still the sucker leaked. I talked to a hot rod buddy and he told me to make a thick cork gasket, take yellow weather stripping cement. stick the gasket to the pan side and let set for a day. I took it further, I put a weight on top of the pan and pressed the gasket there for a week. Set nice and flat and permanent, like iron. Then I took black RTV and applied to the other side of the gasket and the tranny casting, bolted up right away(because I tried to let tack up and quess what, it leaked... snugged up the pan and let set for another several days.....No leaks !!!! END OF STORY !!!!

Jeff

Jeff1967 · « **Reply #14 on:** August 27, 2009, 08:00:00 PM »

Now as Glen mentioned take a look at other places on the transmission where leaks are coming from that may appear to be coming from the pan. I narrowed my leaks to the pan, dip stick tube and shift linkage. I have the pan stopped but have two others to fix.

Anyone know how to stop a leak coming from where you see red ATF collecting around the main shaft, take a look at the picture below.

Thanks,

Jeff