View Full Version : C4 leak - ideas

08-10-2016, 08:03 AM
My brother and I have been corresponding about a leak from my C4 transmission. It's manifesting itself by a small leak from a crossmember about 9 inches behind the transmission pan and off to the left (drivers side) of it.

The car sat for a few years. Car was parked on Sunday evening and I wiped up about a quarter size spot of pink, transmission fluid on the concrete floor yesterday. Same size spot was back this morning. The dipstick registers full.

My brother says it looks like the pan has RTV on it. I'll get it on ramps and check the bolts. My suspicion is a leak from the converter - either front pump or drain plug.

Looking for other ideas to check as well. Transmission operates and shifts fine.

You can see the spot on the exhaust pipe where it's coming off the crossmember.

http://i104.photobucket.com/albums/m191/scozim/SAM_0052.jpg (http://s104.photobucket.com/user/scozim/media/SAM_0052.jpg.html)

From the left side:

http://i104.photobucket.com/albums/m191/scozim/SAM_0051.jpg (http://s104.photobucket.com/user/scozim/media/SAM_0051.jpg.html)

08-10-2016, 10:33 AM

Front pump or drain plug (I assume you mean also on the converter) would drip up near the front of the transmission. The only thing towards the rear, and high enough to send oil into the cross-member, is the speedo-cable plug, which does have an o-ring to seal it. I would probably be removing the cross-member, wiping it all down to remove all signs of oil (maybe checking the mounts for oil-soak while you are at it - also known as WIAT™) and then look for any signs of oil.

There is also a vent on the very top of the transmission, but that should not blow oil like a whale unless there is an over-fill condition or some off internal pressure because this vent is plugged.

If the oil is just flying back and hitting the cross-member and then dripping off, it could just be the pan. You should be able to see residue there too. These pan gaskets and the pan are susceptible to distortion from over-tightening the bolts, which will cause leaks. These bolts should be tightened just enough to keep them from loosening - and the pan needs to be flattened out every time you install a new gasket.

Good luck tracking it down!