Hi,

I'm going to be replacing my rear differential cover on my 2008 FX4 9.75" axle.

The replacement cover comes with a new gasket.

Should I use just the gasket alone, or use the gasket along with sealant, or toss the gasket and just go with gasket sealant?

Thanks.

 

You didn't say what cover you plan to use? Ford uses RTV only on the OE covers. I tried that and it leaked. If you read the directions for the RTV, you are supposed to wait for 24 hrs or so before putting grease back into the diff. So, I will only use a gasket. A little sealer on the gasket probably won't hurt but it isn't necessary.

 

Just did mine, drained, cleaned with tons of brake cleaner, used orange rtv, hand tighten bolts left an hour then torque to spec. I let sit 3 days before filling. Think about it, the rtv takes a long time to dry inside the pumpkin. No leaks after 3 months.

Gaskets get saturated over time and leak. They are usually just compressed paper. I made this mistake on my rx7 oil pan?

 

The gaskets I bought from Advance for my diff covers don't ever leak.

 

I've had my diff fluid changed twice since I bought the truck. First time they used a gasket, it didn't leak. Second time they used just RTV and it leaks. I wouldn't install the gasket dry, I'd put a thin film of RTV on it without leaving it to cure.

 

I'm an old coot who still uses shellac to help gaskets seal when I deem it necessary.