Today, I changed the fluid and filter in my daughter's 2001 Dodge Neon. I also installed a new Fel-Pro Differential Gasket as it was leaking from that area. Well, it's still leaking, and its worse than before. When I removed the cover from the differential, there was not a gasket, just RTV material. To my knowledge, it had never been removed. Did I miss something here? I've heard nothing but good things about Fel-Pro gaskets, and both surfaces were clean. Any ideas?

 

How did you tighten it down? There's a somewhat specific pattern you need to follow.

 

I used a crossed pattern, started at the bottom left corner and then went up to the upper right, then upper left and bottom right and continued on down until all were tightened. I've got the car up in the air right now and I've loosened all the bolts, thinking that I may have overtightened. I'm just going by feel, no torque wrench.

The leak is at the very bottom of the cover.

 

Hmm. All I ever used were the gaskets and I never had a leak. Just snugged the bolts real good. I didn't torque them down too much. All of the old RTV was removed?

 

Yeah I cleaned up both the cover and the surface it attaches to real well. I'm going to try the RTV method and hope for the best.

 

If I'm remembering correctly, there was a trick with the RTV. Something like not fully tightening the bolts while it cured, and then finish tightening after it cured for how ever many hours.

 

The 1st time I changed my auto trans filter and fluid I got the filter and gasket from NAPA. I did a leak check after I was done and it was leaking on one side. I tighten up the bolts a little more and still dripping. Took a while but I found that trans. oil cooler line connecter just above the pan was leaking. Bought some new hose and done.

 

Well, I ended up taking it apart, removing the newly installed gasket, cleaned up both surfaces, again, applied about a quarter inch bead of Permatex Ultra Black RTV Silicone. I started the bolts in each of the four corners and then followed with the remainder and tightened them in a crossing pattern. I didn't wait for the RTV to cure prior to snugging them down. I let it sit overnight and the following day while at work. When I got home I lowered the car and started it so I could get an idea where the fluid level was, added about 3/4ths of a quart. Happy to report that so far no drips. Hopefully my problem is solved. Thanks to those who replied.

 

Hopefully the Ultra Black holds up. I don't recall it being resistant to ATFs.