Noticed some oil drips on the garage floor and I found that my rear differential was leaking oil. It looks like it is just contained to the differential cover, but I noticed a couple of things that I wanted to clarify on before I got too far into the project.

As you can see from the photo below, the leak seems to also originate from the rubber plug on the differential. I'm also led to believe that the rubber plug in question might be my fill point for the gear oil? I spent a fair bit of time looking for a metal plug before I started to scrape off the accumulate oil and grime and discovered the rubber plug.

I'm going to guess that I'm not going to be lucky enough to be able to reuse the rubber plug, or is there something else I can do to address this? And is this confirmed to be the fill point for this particular differential?

 

Yes it's the fill plug. The 9 bolts used a rubber plug after cleaning it up you might be able to use a small amount of black permatex silicone to get a better seal

 

Good to know, thanks for the reply!

While I was giving my post a chance to be read, I started usung some cleaner to start stripping away the accumulated layers of grime and I came across this metal tag hiding under it all. Does this mean that the differential is a limited slip? I was originally going to pop off the cover, drain and then see what differential I had then run to NAPA if I needed the limited slip additive, but it took me longer to reach this point than I'd anticipated, and they just closed. If this is the case, I'll just leave off draining until tomorrow when I can get everything I need so I can pull it back into the garage tonight.

 

Almost every 9 bolt that I have seen had the Borg Warner limited slip differential, Your pictures are not showing up for me.

 

Haha, the picture didn't show up because I'm a dummy and forgot to attach it.

I'm assuming 'approved lubricant' would be the limited slip additive. NAPA's website isn't very helpful finding the equivalent, so I may need to take a further drive to Autozone where I know they at least stock AC Delco.

 

That part that says it's a "SPIN RESISTANT DIFF" tells you it's limited slip.

Read the label on your gear oil before you add a limited slip additive. Some of them come with the additive already mixed in.

 

I was pretty sure that was the case, just wanted to make sure I wasn't jumping to the wrong conclusion. If jumping to conclusions was an Olympic event, I'd have a closet full of gold medals. I figured I'd double check for a change, since a lot of work on this car is new territory for me. Plus if nothing else, my post might help someone else down the road.

Cheers for all the input!

 

Id buy a new rubber plug, to avoid a headache. probably a few bucks.

 

I'd tap it to a pipe size, put in a threaded brass plug, and EFF the rubber plug. ½" pipe IIRC (about 7/8" dia) but I could be wrong.

 

There was a thread on here not long ago about someone who was trying to find a new rubber plug. I can't remember if they were able to find one or not.

 

Weld on a bung.

 

The leakage on the OP's Diff probably represents decades of seepage. I'd try to get a new plug, or after servicing the unit, seal the old plug. They built millions of them w/ the rubber plug, why re-engineer it now? (If the OP is even capable of Tapping it, or welding on a Bung)?