Hey! Check your rearend! - PeachParts Mercedes-Benz Forum

rwthomas1 · #1 12-18-2002, 05:27 PM

I finally got around to changing the rear diff lube today. What came out was nasty looking, brownish snot-colored stuff and only about 1/2 a quart. Probably never been changed. The car is noticeably quieter now. Check yours today! RT

waybomb · #2 12-18-2002, 05:47 PM

I'll do it this weekend. What goes back in? I don't have a real manual yet.
Thanks
Fred

fredjj · #3 12-18-2002, 05:56 PM

In both of my rear drivers I've used Mobil1 Gear Lube. I haven't noticed any change in noise, maybe they weren't noisy to begin with. One gotcha' when doing this -

****Loosen the fill plug before draining the differential*****

The first time I did this on my vehicles I had to use a 5 foot cheater bar to get enough leverage to loosen the fill plug.

rwthomas1 · #4 12-18-2002, 07:49 PM

Funny you mention that... The fill plug was so tight it required a very hard kick to a 1/2 inch breaker bar to get it to move. I put in 75w-90 Gearlube, used Royal Purple as it is what I had. RT

samiam4 · #5 12-19-2002, 01:05 AM

Guys,

Use a 1lb ballpeen hammer. Give the fill plug a couple wacks and it will loosen the threads. Then it will nearly come off with your fingers. Then you won't damage anything with a 5 ft cheaterbar.

Michael

samiam4 · #6 12-19-2002, 01:06 AM

I didn't mean threads... compress or loosen the gasket. Anyway- works like a charm. I do similar things before turning bolts in Aluminum and almost never have siezed bolt problems.

Michael

The Warden · #7 12-19-2002, 03:59 AM

I hate to ask a dumb question, but what size are the fill and drain plugs (or is there a drain plug)? Is it a "normal" bolt, a square bolt, or an Allen head? I should probably do the differential oil in my car...maybe it'll have something to do with the roaring?

And 75W-90's best, I presume? That's what I used in my pickup's tranny...

Thanks!

BobK · #8 12-19-2002, 06:50 AM

Fill plug is 14mm allen, I believe. Autozoo sell a set of three allen head sockets in half inch drive for under $9. I could not believe how much presure it took to get mine loose on my 126. 18" bar plus pipe extension. Turned it so hard I was kinda expecting the car to flip over.

dave240 · #9 12-19-2002, 09:13 AM

hey rw,

I also used the "Royal Purple" product in my car. I used the straight 30w in 4spd manual, and 75-90 in rear.
Been in there about a year now, seems be ok, no leaks etc.

BoostnBenz · #10 12-19-2002, 04:53 PM

I was researching for rebuilding my CVs and found that there was a nice post about how Mobil 1 synthetic can/will clean the dirt and such out of the rear end. I had to take the whole plate off when I pulled out the CVs and it was terrible, so much metal was stuck to it. I must of used almost a full can of carb cleaner getting it clean again. Leaving the rest of the interior coated in the brown stuff I rebuilt the axles and tried the mobil 1 in there. Going to drain it out this spring to see if the mobil 1 did clean itout much. Since I had the plate off I believe I ended up using my 6" vice with the torch and 25" breaker bar (didn't want to risk breaking something w/o the heat).

Oh and I bought some redline 75w90 for replacing the mobil 1. I just put that in the rear of my Talon and it quieted it down a little. I had heavy shockproof redline in it before so it wasn't to much of a surprise....

~jm

Piotr · #11 12-19-2002, 06:08 PM

change my rear diff lube every 20 K miles

The Warden · #12 12-31-2002, 04:05 PM

How much fluid does the diff hold? Also, is there any additive (LS stuff, for example) that needs to be added?

I'm getting ready to pull and replace my axleshaft, and will need to drain and open up the differential to do it...planning to use 75w-90 Redline oil in there if I can find it locally.

Thanks!

engatwork · #13 12-31-2002, 05:25 PM

Warden - have two bottles of gear lube on hand. It will take all of one and some of the other. The problem is that it is hard to get it in there. Make sure you get some good sealant to put on the differential cover prior to bolting it on.

The Warden · #14 12-31-2002, 05:45 PM

Any suggestions on how to get the oil in there? I did my truck's tranny and transfer case last year, and wound up using a hand pump to transfer the new fluid in...I didn't bring my hand pump with me, of course, but a new one's only about $10...I was planning on just doing that, unless you have a better suggestion.

I'm all ears

Thanks! Tryin' to get all my ducks in a row...

samiam4 · #15 12-31-2002, 06:33 PM

If you've got the diff apart,

Please replace the diff side seals while R&R'ing the axles. Also, I believe it is suggested to replace the c-clips that hold the axle in place. They will set you back less than a $1 each.

The case uses a anerobic sealant-no gasket. Some use silicone, or older stuff, but the newer sealants are really nice to work with.

The diff holds (I believe) 1.1 liters?/ 1.1 quarts. 14mm works. I've used a double nutted bolt with red loctite in a pinch- no problems. Remember to remove the fill plug before removing the cover.
What else? The diff needs to be high to maximize room when removing axles. It's an easy job- I can be done in 2-3 hours for both sides, but plan on more.
maybe some brake cleaner to prep the sealing surfaces.

Michael