I have a C4 transmission in a my 66 302V8 that I am having oil leak problems. I put a new cork gasket and it seemed ok for awhile but when it sat for a few weeks, it leaked a little bit. Over a month period it is probably a puddle that is maybe 6" in diameter so not alot of oil but keeps me putting a plastic trash can lid under the car.

My son was saying that the fluid leaks out of the torque converter and saturates the cork gasket. Then I started thinking that in new cars, they don't use gaskets - they use some form of sealent.

Does anyone else have this problem? I could try using sealant on my new high capacity pan, it has a drain plug, what does everyone think?

Thanks

 

verify pan sealing surface is true.
you can straighten over torqued sheet metal pans.
if pan not perfect i would use rtv w/ gasket.
i've had good luck w/ cork on trans pan; i put the red permatex brush on sealant on at least one side of gasket.

 

thanks

I am thinking to get the trans pan from Jegs and RTV - that will seal the pan area and I like the extra capacity/cooling for the hot los angeles summers

 

Clean all oil off mating surfaces.

Clean threads real good w/ cotton bud and solvent; blow solvent dry.

use blue thread locking compound so bolts don't work loose.

Torque pan bolts w/ beam type in/lb wrench or use nut driver to avoid over tightening.

Chance of success w/ rtv and gasket is very high.

 

It might not be the pan at all, might be the fill tube or even the front seal. I think if it was me I would reseal the pan and change the fill tube seal at the same time, then you will know.

The pan, (both engine and tranny) get blamed on a lot of leaks because everything ends up there before it hits the ground.

The fluid will often drain out of the converter and make the level abnormally high causing the tranny to leak on lots of places it would not ordinarily leak. I have read that C-4s are really prone to this issue.

 

good point.
study leak source for sure; not easy sometimes...uhhh.
always use new fill tube O-ring; rtv not good here.

 

I had my C-4 rebuilt and that is when the leak problem started. I kept taking it back to have the mechanic redo the seals (not just the pan). The pan had the worst leaks and I insisted it was leaking from there. The mechanic told me the seal was good all 3 times and didn't want to redo it. You could see it was dented and the edges were probably not true flat.
Anyhow he told me the leak was coming from other areas, so I cleaned up the entire thing and when it was dry I dusted the whole thing with baby powder. The next morning It proved the leak was coming from the pan and not any of the other seals. (powder is missing from the path of the dripping fluid). I finally purchased a new pan along with a new gasket. Used gasket sealant to hook it to the new pan and then a thin coat on the top side. Bolted it on and have never had another drip. The old pan looked like the bolts had been over-tightened, warping the pan at each bolt hole.
There were a few earlier seal drips from above, they all ended up on the pan, so it does look like they come from the pan itself. The dusting with baby powder (or corn starch) will confirm where the actual leak is. Just hoses off when you are done.

 

awesome, thanks guys! my son was saying the fluid would leak out of the torque converter if it sits for a week or two and then the cork gasket with the thin stock pan that is probably a bit warped and ............

I am thinking to hit the dipstick tube while I am at it. anybody have any suggestions on tranny pan? Can anyone tell me if the larger capacity pans are any thicker than the stock one? I am thinking the TCI extra volume or maybe the B&M.

thanks again

 

Straightening a pan rail is pretty simple. Pliers, straight edge, and a couple of ball peen hammers is all you need. If the pan was overtorqued, the holes tend to dimple towards the gasket surface. Use the bal;l peen hammer to dimple them the other way. Use silicone on both sides of the gasket to take up any irregularities.

A common place for the C4 to leak is around the shift shaft. It's just a hole through the case with no buching. Over the years, the hole enlarges and becomes oblong. The seal no longer works. I don't know if there's a simple fix for this, but I suspect not. The real answer is to ream out the hole and install a bushing.