How to diagnose a bad front diff?

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

DeCaff2007

Full Access Member
Joined
Apr 26, 2011
Messages
88
Reaction score
29
Location
Hazleton
OK the deed is done and it was WAY too easy. I found a suitable replacement at a local yard where they pull the part and you pay out the a$$. It should be ready for pickup in a few days.

I wonder how easy it would be to replace the oil pan gasket, since I'm down there anyway, and it's leaking like a biotch.

You must be registered for see images attach
 

u2slow

Full Access Member
Joined
Mar 6, 2012
Messages
636
Reaction score
89
Location
BC
How are the bearings in the ends of the axle tubes? And the journal surface of the CV's? Check how much angulation that spline coupling with the passenger shaft can achieve; it should be virtually zero. If it angles, that could be your rough/crunchy noise.

I havent touched the oil pan. Kind of afraid to.... Lol
 

DeCaff2007

Full Access Member
Joined
Apr 26, 2011
Messages
88
Reaction score
29
Location
Hazleton
How are the bearings in the ends of the axle tubes? And the journal surface of the CV's? Check how much angulation that spline coupling with the passenger shaft can achieve; it should be virtually zero. If it angles, that could be your rough/crunchy noise.

I havent touched the oil pan. Kind of afraid to.... Lol

I didn't really check the axle tube bearings in detail. I gave them a quick glance and didn't notice anything out of the ordinary. As for the cv axle journal surface, there's a decent amount of wear there, too. It's not devastating wear, but if it causes problems with the new diff that's coming in, it'll get replaced.

I should really, really see if I can remove the oil pan (and clear the bottom of the engine) with the front diff out.
 

DeCaff2007

Full Access Member
Joined
Apr 26, 2011
Messages
88
Reaction score
29
Location
Hazleton
Ok, good news and bad news. The good news I went a picked up the "new" differential today. It was actually pretty clean, but oh man was it bare bones. No mounts, no axles, no vent tube, and no gear oil. It did, however, come with a 90 day warranty. Whatever.

I gave the pinion a spin. I'm not pleased. As I spun the pinion, I could almost feel how bad the bearing were inside the case. Lovely. I should have just left the original diff in the Jeep and waited until it failed. At least now I have a spare (which, is important to me).

Alas, I took the cover off the "new" diff to see what I'm in for. The carrier races and bearings are heavily worn and a little rusted. That's what you get for storing used parts w/out oil. The rust would have come off with use. The wear on the bearings/races, however, is only going to get worse.

The outer axle bearings and seals are also bad and have to be replaced.

Sigh...... This is why I didn't want a junkyard part - HOWEVER - after tearing into the "new" diff, I can see that there's NOT a whole lot to it. It actually seems simpler than a GM diff.

I've since ordered new carrier bearings and new axle bearings and seals from Rock Auto, along with the diff cover gasket.

One thing I have NOT done is tear into the pinion gear/bearings/yoke/seal. That assembly spins free, has no play, and there's no noise. That' means NO TOUCH lol!
 

Doing10to20

Full Access Member
Joined
Apr 23, 2020
Messages
297
Reaction score
482
So random info ...i was having a grinding,clunking sounding sound coming from the front end everytime I took off from a stop or turned right or slowed down then accelerated...replaced a hub ,cv, front drive shaft...couldn't get rid of the grinding/clunking thought it could be the diff..long story short my transmission mount was completely gone bushing was trashed ,replaced it all grinding/clunking gone..seems since the bushing and mount was done stuff wasnt aligning right, good as new now
 

duderz7

Full Access Member
Joined
Jan 20, 2016
Messages
1,394
Reaction score
1,105
Location
Weiser, ID
So random info ...i was having a grinding,clunking sounding sound coming from the front end everytime I took off from a stop or turned right or slowed down then accelerated...replaced a hub ,cv, front drive shaft...couldn't get rid of the grinding/clunking thought it could be the diff..long story short my transmission mount was completely gone bushing was trashed ,replaced it all grinding/clunking gone..seems since the bushing and mount was done stuff wasnt aligning right, good as new now
Glad you got it figured! Take a look at your engine mounts, likely in similar shape.
 

DeCaff2007

Full Access Member
Joined
Apr 26, 2011
Messages
88
Reaction score
29
Location
Hazleton
Good news! I was able to finally turn the key after two grueling days of wrenching (and waiting on parts).

It did start, but it took waayyy too many cranks to do so. Immediately, I got a check engine light and abs light. Ironically, upon test drive, the grinding noise up front is gone LOL.

Also, I let it warm up to operating temp and let the antifreeze cycle through. Also, I bled the system and I have nice hot heat coming out of the vents... BUT.... The upper radiator hose is HOT HOT HOT. The lower radiator hose is colder than cold! This is with a new thermostat! Ruh-roh.

I'll start a new thread with the codes it's throwing.

Otherwise, I'll call this one done. The grinding noise ended up being the carrier bearings in the front differential.
 

KJowner

Full Access Member
Joined
Oct 20, 2022
Messages
748
Reaction score
428
Location
Uk
Good news! I was able to finally turn the key after two grueling days of wrenching (and waiting on parts).

It did start, but it took waayyy too many cranks to do so. Immediately, I got a check engine light and abs light. Ironically, upon test drive, the grinding noise up front is gone LOL.

Also, I let it warm up to operating temp and let the antifreeze cycle through. Also, I bled the system and I have nice hot heat coming out of the vents... BUT.... The upper radiator hose is HOT HOT HOT. The lower radiator hose is colder than cold! This is with a new thermostat! Ruh-roh.

I'll start a new thread with the codes it's throwing.

Otherwise, I'll call this one done. The grinding noise ended up being the carrier bearings in the front differential.
Usual Jeep advice is charge the battery up and clear the codes, might just be low voltage upsetting things.
 

Latest posts

Members online

Top