rear diff plug question

[rjgilligan]

I'm changing my rear diff oil. It looks frothy and is silver.  Is there (supposed to be) a rubber seal on the drain plug of my diff. I've got a 79 with a 4.11 rear, but I don't think that matters.  When I took the plug off, there didn't appear to be a seal. There's buildup around the drain plug like it had a small leak.

[Dawa]

there is no gasket/seal. its a tolerance plug (metal to metal) if you want you might could put on some

thread sealer?

[rjgilligan]

Thanks for the quick reply.  I think I'll add a little thread sealer.

[wayno]

I'm changing my rear diff oil. It looks frothy and is silver.  Is there (supposed to be) a rubber seal on the drain plug of my diff. I've got a 79 with a 4.11 rear, but I don't think that matters.  When I took the plug off, there didn't appear to be a seal. There's buildup around the drain plug like it had a small leak.

 

Silver is not a good color, I would start looking for another 411 gearset if I were you.

Is it making noise?

The faster you go, the louder it gets?

Does it clunk or clang?

[Dawa]

oh yeah. silver tranny fluid is bad.

either some shit is getting eaten up and/or the fluid you drained WASNT yellow metal friendly.

did you replace the fluid with yellow friendly GL 4?

[rjgilligan]

Hmm, I replaced the fluid with 80w90. It was some sht it I bought at autozone... green in color.  It didn't look good, which is why I decided to change it.

 

I haven't noticed any noises, but I've been mostly listening to the engine up to this point. To be honest, I don't really know what to listen for... all I know is that I bought the truck from a guy who looked like he didn't give a shit about keeping up on the truck, so I've been going over everything myself.

[datzenmike]

Silver or white could be water getting in maybe from the axle ends? The bung on the diff has a magnet I believe...  same as the transmissions. It collects ferrous metal and should be wiped off so you can compare next oil change. Be sure you get GL5 oil for the diff. Diff oil should be changed every 30K miles but owners change more often than this at it gets ignored. You can switch to synthetic but often it is so slippery it begins to seep out the worn pinion seal

[Dawa]

oh yeah. silver tranny fluid is bad.

either some shit is getting eaten up and/or the fluid you drained WASNT yellow metal friendly.

did you replace the fluid with yellow friendly GL 4?

 

 

Silver or white could be water getting in maybe from the axle ends? The bung on the diff has a magnet I believe...  same as the transmissions. It collects ferrous metal and should be wiped off so you can compare next oil change. Be sure you get GL5 oil for the diff. Diff oil should be changed every 30K miles but owners change more often than this at it gets ignored. You can switch to synthetic but often it is so slippery it begins to seep out the worn pinion seal

 

oops my bad i confused myself.  

 

silver tranny fluid = bad. use GL4 for transmission fluid

 

but we arent talking about the transmission here..

dif fluid is GL5. sorry for any confusion....

[rjgilligan]

There were some metal flakes on the magnet, and a buildup of silvery grease (it felt/looked more like a grease than an oil). Then it poured out foamy and dark.

 

I can't find where the water could have gotten in, but who knows when the PO changed this last, if ever.

[datzenmike]

Here's how. You drive it and the inside gets very hot. Just grab the diff housing with your hand after a drive. It's so hot you can't keep your hand on it. Now back down a boat ramp to get your 12' on the trailer and the differential is submerged. The cold water contracts the warmer air inside and is sucks water in through the breather.

[datsunaholic]

Or just park it on wet pavement or wet grass on a rainy day.  As it cools, it pulls that humid air in.  Over 34 years, that's a lot of moisture.

[datzenmike]

True that.... and why the oil should be replaced every 30K miles. Trouble is the owners change more often and no one checks it. Bet there are trucks out there with 200k on them and their third oil change.