Front differential fluid change problems

GreenJeep511

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Original poster
Joined
Mar 17, 2019
Messages
20
Location
Shelby County, Alabama
**I did use the search function and did not find an answer** Background: 2003 X model 150K miles, all stock. have noticed a humming noise lately that I've been trying to chase down. It sounds like it's coming from the front end. It's almost like tire noise or wheel bearing noise. I had the wheel bearings checked, they're fine. U-joints looked fine. My mechanic ended up replacing a sticky caliper. Btw, it was in the shop not specifically for the noise but for another issue, which of course was the sticky caliper.

Anyway, the noise has been under my skin so I've been scratching my head trying to chase it down because I swear it wasn't there a few months ago. Mechanic did not notice it when he drove it, and my fiance says it's the same noisy Jeep it's always been. So today, I decided to give the diffs fresh fluid, bought some 80W-90 conventional, some brake cleaner, and some RTV and planned to pull the covers and have a look. I had already checked the rear fluid, which appears to have a slow leak. Fluid was not very low at all, no obvious metal shavings, but was definitely dirty.

I started this morning with the front. Whoever did the RTV on this thing was a ******** idiot. It's everywhere. I looks like a toddler on meth went crazy with it. I ran into one problem immediately. The first bolt down from the top on driver's side is unreachable because of the track bar. So I'm going to have to jack it a bit and put the frame on jack stands to get to it. No big deal right? So I break loose the fill plug first because I was worried about not being able to get it out easily and didn't want to mess up the set on the RTV when I replace the cover and go to fill it.

There comes a FLOOD of chocolate milkshake. F*ck. Obviously there's water in the diff. Now when I say flood, I mean the ENTIRE diff housing had to have been full of this contaminated gear oil.

My question is, worst case scenario, if I can't get the clearance I need to get to that one stupid bolt from jacking it (if my jack stands are too short), can I pump the bad fluid out and fill it with fresh fluid, leaving the cover on, and be safe enough to drive it to the shop?
 
Can you post a picture up? I’m not sure why you are having trouble reaching one of the diff bolts on a stock jeep. Are you using sockets or wrenches? I would definitely want to get the cover off and flush out all the crud that wouldn’t come out with a pump. If you have that much liquid in there it could be failed inner seals or vent tube which should be addressed. The noise your hearing could be the carrier or pinion bearing with shit in them, front driveshaft or unit bearings. Without hearing it I’m guessing.

If it was mine I would remove cover and clean thoroughly. Spin tires while on stands and cover off to listen for your sound at the diff and wheels and then recover with fresh fluid in it. Check vent line for cracks or just replace it. I’d remove the front driveshaft to take that out of the sound equation and take it for a spin.
 
It should be easy to either fit a box end wrench in or drop the axle end of the track bar. There shouldn't be any need to drive it to a shop.

When you have it open, spray the entire housing out with brake cleaner to get the water out. Make sure any cavities are clear of the brake cleaner before sealing it back up.
 
I’ll post a pic when I get back to the house, ran out to run an errand. I thought about dropping the end link on the track bar but wasn’t sure if it would be a hassle.
 
Using sockets. I could use a box wrench but there ain’t much room and still wouldn’t be able to get the torque wrench back there to bolt the cover back on
 
Using sockets. I could use a box wrench but there ain’t much room and still wouldn’t be able to get the torque wrench back there to bolt the cover back on
Do yourself a favor and as suggested above, just drop the driver's side tie rod. Once you get the tie rod nut off do NOT NOT NOT pound on the top of the stud to get it to drop. Using a hammer to pound on the stud to unseat it will be unsuccessful and likely mushroom the top of the stud.

This is the fast & easy way to unseat the stud, it is the time-honored way among experienced mechanics/Jeepers. Use a BFH (big effing hammer like a small sledge) to give several MANLY whacks on the side of the knuckle which will pop the stud loose as shown below. If you can't get it to pop out, go put your big boy pants on and have another go at it with that BFH.

If you use the BFH properly with a few manly hard whacks, that stud WILL pop out. No need for a puller, heat, or anything else the less experienced will suggest.

This is me several years ago when I was like 69-70 so don't tell me you can't get it popped loose unless you're older than me.

Dropping the driver's side of the tie rod will allow you to easily get a torque wrench on all of the diff cover bolts.

BFH-Knocking-Tierod-Loose.jpg
 
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Rather than jacking up the jeep or disconnecting one end of the tie rod it is often possible to get a wrench on what otherwise looks like an inaccessible differential cover bolt or fill plug simply by turning the steering wheel all the way to the right or left thus changing the spacial relationship between the tie rod and cover.

Always try the easy method first.
 
Rather than jacking up the jeep or disconnecting one end of the tie rod it is often possible to get a wrench on what otherwise looks like an inaccessible differential cover bolt or fill plug simply by turning the steering wheel all the way to the right or left thus changing the spacial relationship between the tie rod and cover.

Always try the easy method first.
Didn’t even think of that
 
Do yourself a favor and as suggested above, just drop the driver's side tie rod. Once you get the tie rod nut off do NOT NOT NOT pound on the top of the stud to get it to drop. Using a hammer to pound on the stud to unseat it will be unsuccessful and likely mushroom the top of the stud.

This is the fast & easy way to unseat the stud, it is the time-honored way among experienced mechanics/Jeepers. Use a BFH (big effing hammer like a small sledge) to give several MANLY whacks on the side of the knuckle which will pop the stud loose as shown below. If you can't get it to pop out, go put your big boy pants on and have another go at it with that BFH.

If you use the BFH properly with a few manly hard whacks, that stud WILL pop out. No need for a puller, heat, or anything else the less experienced will suggest.

This is me several years ago when I was like 69-70 so don't tell me you can't get it popped loose unless you're older than me.

Dropping the driver's side of the tie rod will allow you to easily get a torque wrench on all of the diff cover bolts.

View attachment 91788
It’s the track bar that’s in the way, not the tie rod. I hear ya on the “no excuse” 😆 my grandad is 75 and he’s leading a group on a motorcycle ride along the Rio Grande right now.
 
Success! Jacked it up from the diff and set a jack stand underneath driver frame rail behind LCA bracket and let her down with a second stand up the axle and the wheels chocked just in case.
91809
 
Thanks for the ideas y’all are great. Used a whole can of brake cleaner and there’s still some milky film on the ring and pinion, and a bit of sludge still trickling our from behind the pinion, gonna have to grab more. Disappointed but not surprised that there’s some rust on the mating surface, mainly on the cover side.

Toximus, correct no leaks from axle tube. You still think the seals are good? Which would mean the only point of ingress would be the breather hose?
 
Thanks for the ideas y’all are great. Used a whole can of brake cleaner and there’s still some milky film on the ring and pinion, and a bit of sludge still trickling our from behind the pinion, gonna have to grab more. Disappointed but not surprised that there’s some rust on the mating surface, mainly on the cover side.

Toximus, correct no leaks from axle tube. You still think the seals are good? Which would mean the only point of ingress would be the breather hose?

Yes, most likely the breather hose. Did you go through deep water? Did you check that they aren't cracked? You may need to raise them higher. I (lightly) milkshaked a rear diff last week due to water up to the hood, thought I was being careful, but it happens. Changed the fluid after the trail and its fine.