Rear end Oil Stinks!

[BLUEDOT37]

Nooo, not that rear end, automotive differential gear oil.

Just changed my Mk.III Supra's LSD (nooo, not that LSD, though sometimes I wonder the way it acts) differential oil as it started chattering (again). Decided to try conventional oil, & some friction modifier additive, this time since high end synthetic oils haven't worked out any better, & some worse.

It's only been about 10,000 miles (9 yrs. ) since I did it but it sure STINKS for that amount of use. (High mileage oil is even worse!). Cleaned everything up & threw out the old rags but the garage still smells.

Fresh differential/gear oil doesn't smell bad. Does it smell so bad because it's not refined as much as, say, motor oil? Or is it because something funky's going on in there I'm unaware of?

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[Hotshot9]

Not sure why it stinks so bad, but I know what your talking about. Maybe heat related that makes it stink. You mention chatter noise. sounds like you have a meshing misalignment with you gears. I have a 1967 chevelle I replaced ring and pinion in and getting the meshing just right was tricky. but now I have no noise at all And it has a 4:10 gear now.

 

[Wishbone]

It does smell bad! I had to change my last year because my rear end was leaking.

 

[oldman10mm]

Chattering is a result of lack of friction modifier additive,LSD clutches nearing the end of their service life or improper gear lube. Gear lubes are classified as GL-1 thru GL-5,gotta use the proper dash number per vehicles manufacturer recommendation.

 

[BigCityChief]

The sulfur and phosphorus used in gear oils are the "smelly" culprits.

 

[Ethang]

Question on the "chattering" is it a noise or more of a vibration?

My wife's Explorer will have an acceleration vibration at times, but it is not consistent. It is coming from the rear end.

 

[4barrel]

Limited slip rear ends do this and make a little noise when you turn slow because someone probably added the wrong fluid. The older and hotter fluids smell like that. Most any fluid that smells bad needs to be changed. Transmission--power steering--rear end. You have to know what it is supposed to smell like and color is a factor also. A trained nose will tell you when it needs to be changed. Like burnt transmission fluid.

 

[JSR III]

WAY too many opportunities here to make a funny comment but I just had my last ding expire so will leave well enough alone.

My wife's Explorer will have an acceleration vibration at times, but it is not consistent. It is coming from the rear end.

This one is way easy.....

 

[4barrel]

Question on the "chattering" is it a noise or more of a vibration?

My wife's Explorer will have an acceleration vibration at times, but it is not consistent. It is coming from the rear end.

If you have an older Explorer with v6 and 4 wheel drive and overdrive 85% were limited slip 373 rear ends.

 

[Hillbilly77]

Yup. Differential oil stinks.

Fresh synthetic 15w40 diesel oil..... Now that stuff smells good.

 

[NYlakesider]

Been around cars all my life and even worked a few years part time in my buddies speed shop/garage. I know well automotive smells.

With that said there really not that bad compared to say cleaning out a grease trap or running a large bore sewer cleaning tool.

Retired pipefitter here and I know of what I say! Apprentices tend to get the ''good'' jobs in a busy plumbing shop!

 

[Vulcan Bob]

Yup is sure does! If I would happen to spill some on my work cloths everywhere I went folks would say, what is that smell?!

 

[Ethang]

If you have an older Explorer with v6 and 4 wheel drive and overdrive 85% were limited slip 373 rear ends.

it's a 2003 with the V6/4wheel all time/OD.

Smelly rear end jokes aside, we bought it a year ago. the fluid level was fine when my mechanic checked out the truck, but never considered the wrong fluid had been installed. the vibration just started happening about 4 months ago.

 

[mr.jbk79]

it's a 2003 with the V6/4wheel all time/OD.

Smelly rear end jokes aside, we bought it a year ago. the fluid level was fine when my mechanic checked out the truck, but never considered the wrong fluid had been installed. the vibration just started happening about 4 months ago.

This could be a rear driveshaft/u-joint starting to fail.

 

[Ethang]

That wont make it vibrate in a straight line--just when you go around a corner below 15mph The wrong fluid makes the clutches sticky and jerk and pop. Even with a fluid change it could take a while to smooth out with a p.t. unit.

It's more noticeable when starting out and turning. I had the mechanic check the u-joints when we bought it and they were in good shape.

Might try a fluid change just to make sure. I'll smell it when I drain it out....

 

[BruceM]

Check all factory service bulletins for the "fix" for this. I had two Explorers with this issue and it took a little digging for the dealer to find the cure but it's out there. Both were limited slip differentials. I wish I could remember what the fix was but unfortunately, I can't.

Bruce

 

[DWalt]

I has a 1989 Chevy S-10 once that specified ATF as the rear differential lubricant.

 

[jdh]

After my MKII road course race car (RIP) got Mobil 1 75W90 LS there were no more peg-leg/single black mark tire cleanings leaving pit lane. I changed it each season even though it never showed signs of needing to be changed. The LS has the needed friction modifiers and additives mixed in the bottle.

 

[BLUEDOT37]

Chattering is a result of lack of friction modifier additive,LSD clutches nearing the end of their service life or improper gear lube. Gear lubes are classified as GL-1 thru GL-5,gotta use the proper dash number per vehicles manufacturer recommendation.

Yep, it's the limited slip's clutch plates making noise when you turn, usually at slow speed. It's always been ornery. It takes GL-5. I've tried several premium synthetic brands, that included a limited slip additive already in it, plus added a separate additive but haven't found the one it likes.

Saw a couple Toyota forum posts that said these problem childs sometimes just prefer conventional/mineral oil & they've had good success with the FoMoCo limited slip additive, which is what I tried. So far it's happy! Hopefully it'll stay that way.

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[rwsmith]

If it's that thick.....

If it's that thick 90 weight stuff it has a lot of sulfur in it.