Differential cover leak

[jupoa]

OK, as long as we're discussing rear axle leaks, my differential cover has had a slow leak for a couple of years now. Just enough to leave a saucer size stain on the driveway if it is parked for a couple of months.

About a year ago, I removed the cover, changed the oil, and reinstalled the cover using the silicone form-a-gasket stuff because the auto parts stores didn't carry paper gaskets for it. The vent tube was clear.

One trip and it started leaking again. I would do it over but synthetic oil is too expensive to risk repeating whatever mistake I made the first time.

How do I insure success next time? Make my own paper or cork gasket?

I have a 1997 F53 208" wheelbase chassis.

[Jimmyzw22]

There has to be a gasket in there or it will eventually leak. Differentials have huge heat cycles and without some sort of gasket the bolts will loosen up. Use a good gasket and gasket material and then blue lock-tite. Notice as you drive around how many differentials you can see that look rusty or the paint has come off, that is from the heat cycles.

[RustyJC]

The Dana 80 rear axle in my truck does not use a conventional paper gasket. The cover is sealed with Permatex UltraBlue RTV Silicone Gasket Maker 81724. This product is specified for differential covers and has a working temperature range of -65 to 500 degF. I used it when I drained my differential and replaced the lubricant with Royal Purple synthetic some 5 years and 30,000 miles ago - no leaks since.

Rusty

[Hikerdogs]

I agree with RustyJC. Very few if any differentials still use a paper gasket. The key to getting the RTV to seal is having ALL the previous sealant and any gear oil removed from the sealing surfaces.

Use a wire brush in a drill to remove the sealant from the cover. Then cover the opening of the differential and use it again on the housing. Clean all the oil that might spill out of the differential with a paper towel or cloth. Any dribble across the sealing surface will result in the sealant not adhering to the metal and eventually a leak. Be sure to clean all the surfaces with brake cleaner of carb cleaner prior to applying new sealant. When everything is clean and dry the sealant will adhere properly.

I've changed hundreds of differential covers, engine oil pans, and transmission pans. If you use the proper sealant and keep everyting clean and dry it'll seal properly for many years to come.

[jupoa]

Thanks for the replies. As usual, some very useful information.

I was reasonably careful to clean the surfaces before the cover was reinstalled but the RTV I used was just some generic stuff that was handy at the time. That may have explained the failure.

Even with everyone else having success using the RTV, I still prefer a gasket to goo. If I can find a sheet of gasket material large enough, I'm going to cut my own gasket. Wish me luck.

[jupoa]

Good news for those of us, like myself, who are RTV impaired. Fel-Pro makes a differential cover gasket, RDS 55447, that fits a 1997 F53 with a Dana 80 axle. It is only listed for F53s from 1988-96 but it fit my 10 bolt cover just fine and may fit other years as well. It may be that in 1997, although they were still manufacturing the same differential housing, Dana went to the dark side by using RTV instead of gaskets from the factory , thus there are no gaskets listed for 97 on.

Anyway, I installed my differential cover gasket today and am looking forward to a spotless driveway for years to come .

Thanks again for all your replies.

[gasser 38]

Quote:

Originally Posted by jupoa Thanks for the replies. As usual, some very useful information. I was reasonably careful to clean the surfaces before the cover was reinstalled but the RTV I used was just some generic stuff that was handy at the time. That may have explained the failure. Even with everyone else having success using the RTV, I still prefer a gasket to goo. If I can find a sheet of gasket material large enough, I'm going to cut my own gasket. Wish me luck.

I also let it sit several hours or even overnight before refilling lets the RTV set up

[GOLDWINGER2]

If your leak comes back check your cover for flange distortion.
J