changing differential fluid

[chips2481]

Hi I have a differential that the bearing are making noise. I want to put some lucas oil stabilizer in it because I have heard it helps and I want to wait until spring to replace it. I was looking at the diff and I didn't see where you drain the fluid. I found a bolt with a star wrench hole in it a little over half way from the bottom of it and then there was a normal wrench bolt near the top. Do you just maybe loosen all the bolts on the back of it to drain it or am I blind and not seeing the drain hole. Also I found out in the rain that I have posi because the whole back end would slide to the right, is this something all truck differentials have? When I go to buy another one from the junk yard I don't want to be left without it. Is there anyway of telling if it is all time posi, like when you go around a corner both tires spin no just one?

 

[Exploderpilot]

There should be a tag under one of the bolts on your rear end with a code on it that tells you what's inside(in code of course)
just to know a little bit about your truck though, it might be good for you to have a look. yes, opening the rear diff cover is a just fine way to empty the fluid. there's a little bit of a lip, so when you open it, some fluid will remain at the bottom, and so you'll keep a little old goo in there if you don't scoop it out.
about the posi, you probably have a trac-loc, which is a factory limited slip,
but no that's not full time.
here's how to figure out what you have....

 

[chips2481]

cool thanks wish I had full time are they expensive?

 

[Exploderpilot]

by full time, do you mean locked all the time? no, you don't want that. a locker, like an ARB, is only locked when you want, by a switch in the cab. a spool, which is full time, locks the axleshafts together all the time. good in the dirt, bad on the street. some people do it anyway, and just live with it,(i have for a while) but it's really a pain, and hard on tires and rear diffs. what you have is pretty darn good compared to some cheaper products.

 

[chips2481]

oh I thought it might be easier on the diff since there wouldn't be so much pressure on one side all the time when you turn. Which wheel spins when you turn, when you turn to the right the right or left wheel spins? With all time is there a huge difference when you make corners?

 

[aldive]

To get the fluid out, simply remove the cover and let drain. Be sure to check that you can get the fill plug out prior to draining the fluid.

Clean the cover sealing surface as well as its mating surface. After that put a bead of RTV on the cover, let it set for a while and then reattach the cover. This is followed by removing the fill plug and adding the oil ( I recommend full synthetic oil ). Reinstall the plug.

Its very easy.

Good luck ....

 

[chips2481]

Ok I am a bit confused. First what is RTV? Next how much fluid do you put in. There are 2 plugs I found one on the top with a normal wrench type plug and another a bit above the middle of the diff with a star wrench plug.

 

[aldive]

Ok I am a bit confused. First what is RTV? Next how much fluid do you put in. There are 2 plugs I found one on the top with a normal wrench type plug and another a bit above the middle of the diff with a star wrench plug.

RTV - silicone ( Room Temperature Vulcanisation ).

The plug that a 3/8' drive will fit in is the fill plug.

 

[chips2481]

Great thank you. I hope that lucas oil stabilizer will quiet down the bearings alot until I have time to replace the whole thing!

 

[gijoecam]

The Lucas Oil Stabilizer will not help save the bearings. If they are making noise, it's too late. The damage has already been done. You're already grinding metal on metal, and if you think this will prolong their life, you will be sadly disappointed.

Make the proper repairs now to save yourself a lot of money later. One bad bearing in a diff can easily take out every bearing and gear back there. The longer you wait, the worse it will get, and once it starts making noise, the entire axle's demise isn't far away.

There is no magical oil additive that will cure your problem.

-Joe

 

[chips2481]

how hard is it to change the bearings? Or would it be easier to buy a whole used diff?

 

[gijoecam]

Depends on which one(s) is/are bad. If it's an axle shaft bearing, it's a shade-tree mechanic job. If it's a pinion or carrier bearing, you need some expertise in rebuilding differentials to do it properly. Pinion depth and carrier shimming may be necessary if it's the pinion or carrier bearings, as well as a replacement crush sleeve every time you try to set the proper pinion depth. Rebuilding a differential is almost as much art as it is mechanics.

-Joe

 

[chips2481]

wow looks like I am buying a used one then. Thank you