Change my rear diff fluid or no ?

[98expo]

Hey guys I recently had my abs light come on so I got it scanned and it was for the rear abs speed sensor. I bought a new sensor and went to replace it, and the old one was covered with metal shavings. Which explains why the light came on and wasnt working. But my question is, the truck has 121k and not sure if anyone ever replaced the fluid and now the whole rear end is full of metal shavings. Should I try replacing the fluid and install the new sensor or will I hurt the rear diff with new fluids ? I heard sometimes its good to just leave it alone and I would hurt it more by replacing it. If anyone know please help! thanks

 

[sean99]

It will not hurt to change the fluid.

 

[Nato X]

You gotta change the fluid. I would also recommend adding Lucas oil additive to it as well. Dont need much, about 25%. I ran a 2001 Peterbilt with Lucas in the diffs and tranny(manual) and noticed cooler temps in all. Depending on how much metal you find it, its also a cheep trick to silicon a small magnet to the inside of your housing if theres clearance. I plan on doing this job, too, in the next week or so. Its possible that there may already be a magnet in already. As Im writing this, though, Im wondering if a magnet would screw with sensors??????? hmmm??? Maybe someone else can chime in?

 

[mikepier]

Change it, its not that hard. While you have the diff cover off, spray paint the cover to make it look nice and protect it from rust.
Someone on this forum also suggested lift up each end of the axle with a jack so all the diff fluid drains out of the axle tubes.
Also try to drain the fluid when its warm. 80W90 weight oil does not flow so fast when its cold.

 

[explorer1995]

Id change it also, i wont hurt any and especially if you have that many miles and may not have ever been changed before. cheap maintenance compared to what could happen if it never gets changed.

 

[98expo]

ok thanks guys i will do that!

 

[ranger7ltr]

Should I try replacing the fluid and install the new sensor or will I hurt the rear diff with new fluids ? I heard sometimes its good to just leave it alone and I would hurt it more by replacing it. If anyone know please help! thanks

Changing differential fluid is simple maintenance...Just like with a transmission...And the metal shavings you found were on the sensor correct? It is a good bet that this is the first time this sensor has seen the light of day since being installed in the diff housing on the assembly line...

I do not see how changing the lubricant could hurt the internals but if it does, then just like with a tranny that dies after changing fluid, it was on its way out before now...

Change the fluid[recommend going to synthetic], clean the old one and/or install the new sensor and add the friction modifier, if required, and mark this task off your list of items that need to get done to maintain your truck...And as stated earlier, heat the diff up before changing it...Whatever weight diff fluid is there flows better warm or hot...

 

[Big Z]

You might be able to find a magnetic plug; my fill plug (no drain plug) is magnetic, so be sure to look at/clean yours. Wouldn't hurt to run some cheap oil in it for a little while to flush out more metal unless you're taking the cover off and can clean things from there. While you're at it, you might as well check/change your front diff and transfer case fluid.

 

[Fifty150]

Change your diff cover. Mag Hytec makes covers that hold a gallon of fluid, has a magnetic drain plug & dipstick, and cooling fins. The extra capacity and cooling fins helps you to run that fluid at a lower temperature and prolongs the life of the fluid. The magnetic dipstick allows you to check the fluid and wipe off collected metal shavings. Those metal shavings would have otherwise been floating around in your differential. It's a sound investment, but expensive. If you plan on keeping your truck, then do it.

 

[mikepier]

You might be able to find a magnetic plug; my fill plug (no drain plug) is magnetic, so be sure to look at/clean yours. Wouldn't hurt to run some cheap oil in it for a little while to flush out more metal unless you're taking the cover off and can clean things from there. While you're at it, you might as well check/change your front diff and transfer case fluid.

Great advice, just like to add with the front diff, you can't access the cover unless you drop the whole axle, so most people just suck out the old fluid through the fill plug, and put new fluid back in.
The transfer case is easy as it has a drain and fill plug.

 

[Big Z]

Aye, I used a $10 suction pump on my front diff. It's also a pretty handy thing to have around for adding fluids in the diffs, transfer case and manual transmissions.