3500 02 cummins drw

 

hey guys i just took off my drain plug for my rear diff after driving about 3 weeks after changing the oil right after i purchased it, when i took the plug out a bunch of pressure released and went pooof. when i inspected the cap it had a coating of what looked like a gray silicone but it was obviously metal. ive never seen anything like it, no chunks or long bits just what looked like drywall mud. would this be normal? i just got the truck and when i first serviced the rear there was little no no metal. i put75-140 in the rear.

i dont know if this would make a difference but i ended up having to repair the front end diff as it was pushed back about half a foot over clipping it a concrete slab.

 

thx i know this was long and painful just adding all the info i could

Sounds like your vent may be plugged.

Yep, clean the obstruction in the diff vent line/cap and you should be good to go.

Plugged vents are common issues... Out here they get plugged with mud and then blow out pinion seals and axle seals.

  On 2/21/2023 at 3:14 PM, Mopar1973Man said:

Plugged vents are common issues... Out here they get plugged with mud and then blow out pinion seals and axle seals.

Sounds good I’ll pick up a new vent tube from a hardware store and replace the fluid. Thanks 

If you are smart is running the tube to the highest point you can without kinking the hose. Just keep in mind if you play in deep water you need to go higher than the deepest water you might travel. Like I learned as I crossed a deep creek the vent for my front axle managed to pull water in as the differential cooled a vacuum was created and the tube wasn't tied in a good location and pulled water into the differential housing. Abet it was a small amount but playing all day running 4WD and crossing creeks and deep mud holes yeah the front diff was milky water in the gear oil. Opppssss.  

  On 2/21/2023 at 3:09 AM, DodgeRam2002 said:

looked like drywall mud. would this be normal?

I would say yes.  First time I changed my fluid when getting the truck there was a lot.  And there was a lot the next couple of times as I changed the fluid in shorter intervals because I swear at 270k miles it was the stock fluid - so, so nasty, viscous, and black.  Then a couple of months ago I drained the axle fluid again when I wanted to adjust the preload in my limited-slip diff, and there was a little less than there used to be.

All fluids should be changed by 30k. Front and rear axles, transfer case, auto trans, power steering, brake fluid, etc.

  On 2/21/2023 at 10:52 PM, LorenS said:

I would say yes.  First time I changed my fluid when getting the truck there was a lot.  And there was a lot the next couple of times as I changed the fluid in shorter intervals because I swear at 270k miles it was the stock fluid - so, so nasty, viscous, and black.  Then a couple of months ago I drained the axle fluid again when I wanted to adjust the preload in my limited-slip diff, and there was a little less than there used to be.

 Yea it was on the actual magnet that look like drywall mud very very fine metal I would assume, I didn’t put limited slip additive in because I figured it wasn’t limited slip as I couldn’t see it on the tag

  On 2/22/2023 at 12:06 AM, Mopar1973Man said:

All fluids should be changed by 30k.

Clearly they weren't on my truck.

  On 2/22/2023 at 12:06 AM, Mopar1973Man said:

All fluids should be changed by 30k. Front and rear axles, transfer case, auto trans, power steering, brake fluid, etc.

is there a way to see if my diff is limited slip, theres no tag on there. but its a 2002 3500 auto drw

Remove the differential cover is the easiest... Then look at the 3rd member and look at see if the spider gears are visible. If not then it's a limited slip.

 

I'm not sure but if you have it jacked up on the rear axle and then spin a tire if both spin in the same direction typically it's a limited slip. If one spins in the opposite direction then it's an open differential. 

 

Find the ratio mark a tire in one spot on the inside and the driveshaft in a spot. Then turn the driveshaft and count the turns of the driveshaft to one turn of the tire. If the driveshaft turns roughly 3 and 1/2 turns it's a 3.55 gear ratio. If it turns little more than 4 turns then it's a 4.10 gear ratio. 

 

Now if you upsize the tires 1 size from 265/75 R16 to 285/75 R16 that 1-inch change will make the final ratio to the ground 3.42:1 on a 3.55 gear ratio. If you do like I did and change one size down to 245/75 R16 on a 3.55 gear ratio it will make the final ratio 3.69:1. Be careful with tire size changes with 3.55 gears. This a huge problem I'm trying to teach people don't put 35-inch tires on a 3.55 geared axle being the final ratio now is 3.21:1 to the ground and will cause damage to transmissions. 

Clogged vent hose. Same thing happened to me.

 

Click my post below, scroll down to the last post on the bottom of page 2 to see picture of my clogged vent hose. Clogged with mud-wasp insect junk. 

 

 

Edited February 24, 20232 yr by Ironforger