possible bad rear diff? need advice

[salisburyv]

hey all. I did search, and read quite a few posts which did not address my problem. I was pulling into my gas station the other night and I could hear/feel a rear wheel locking up. put in some gas, had wifey with me, so I babied it to make it home. Finally had a min today to take a look. I jacked up the rear so both wheels were off the ground. started her up and put it in drive, I watched the rear wheels, I applied no gas, just brakes, to see if they locked up. nope. I replaced the rear pads at the beginning of the summer, had no issues, no noises. I let it run in drive for about 10-15 min, hoping that getting it to operating temp might help it to happen. nope. I removed the jack stands and lowered her down. took a spin thru the neighborhood. Sure enough, first turn to the left I felt the left rear wheel lock up, I could see and hear the tire not spinning while I was making a right turn. then left turn. I suspect there's a problem internally with the rear differential. 219k. I had the fluid changed when I got the truck 5 or so years ago.


has anyone heard of this happening to a 2013 Yukon SLT awd? is there anything else I can do to confirm my diagnosis? I don't have a lift. and if it is what I think it is (bad rear diff) I am really gonna have a hard time paying a shop to confirm my findings. Like everyone else, money is tight, still have a few payments left and would struggle to have 2 car payments, as I don't think it's worth fixing.

I could possibly source a. used rear end and my brother in law has a lift and could help me install it. I just need advice on what to do. did I miss anything? when I bought the truck I had all the fluids changed, and its been good since then. please. let me know your thoughts.. thanks !!

 

[strutaeng]

You should probably drop the differential cover to inspect the internals...

Do you know if you have the G80?

 

[salisburyv]

You should probably drop the differential cover to inspect the internals...

Do you know if you have the G80?

I don't know. what would I. be looking for? chipped teeth on ring and pinion? metal debris? thanks for the reply

 

[j91z28d1]

is it snow covered roads? if you have the g80 option. look. in your. glove box for the rpo code. it's a locker, when one wheel spins faster than the other. the weights will lock one wheel speed to the other making it a posi. it's only supposed to happen when say you're in the mud and one wheel spins and the other doesn't. it will. lock both together to get out out and the once you do like 25mph, a different set of weights force it to unlock.

sometimes they get sticky. a fluid change with the correct fluid could. help. I suggest that I stop by a gm dealer and buy 2 qt of fluid based off your vin number. as all the auto parts store has some amount of limited slip additive in it. and even those this has clutches, it needs zero limited slip additive in it. because it's designed to lock and unlock. not slip like a posi in a car would.


most people have no issue with auto parts store fluid, but I found a small amount of posts talking about it. and after I used it, mine tried to lock in a parking lot with zero tire slip. so I went to the dealer, paused double the amount per qt. but it has never done it again.

go to youtube and search for g80. there's tons of videos explaining how it all works and what to look for. you probably don't need a new diff, but if you do. guys here get used ones for. under 500$ for the whole axle low mileage used. you can even upgrade at the time. you definitely don't need to sell the truck over this, unless you really just want to. especially having access to a lift. Just having a garage to work in is more than most diy guys have access to.


I guess I should ask if the dash is flashing traction control or stability control active while the rear is locking. that could be totally different if it's applying the rear brakes

 

[Marky Dissod]

What j91z28d1 said. Time to change rear diff fluid AGAIN. Drain rear diff fluid into cleanest container possible, so you can carefully examine it.
And even though I normally do not suggest volunteering to get ripped off by dealer pricing, this is once case where it's worth the premium,
especially if you can find a deal on it.

Stick your VIN into this web address after the = sign

Free GM Vin Decoder | GMPartsGiant

Free GM VIN Decoder - Do a VIN lookup to acquire specific car information. Ordering exact-fit parts has never been this smooth and hassle-free on GMPartsGiant!

www.gmpartsgiant.com

Use that same website to find the correct rear diff fluid - then go shopping for THAT rear diff fluid ANYWHERE ELSE that's cheaper.

 

[89Suburban]

If it is the spider gears starting to fail it would give you a skipping sensation and if you made a slow turn it wouldn’t catch the good part of the gear and feel fine. That will get you a few more miles to make it to the shop before it totally fails.

 

[salisburyv]

ty. I really don't want to sell her. I put a lot into it, and despite this hiccup she's been good to me.

 

[salisburyv]

is it snow covered roads? if you have the g80 option. look. in your. glove box for the rpo code. it's a locker, when one wheel spins faster than the other. the weights will lock one wheel speed to the other making it a posi. it's only supposed to happen when say you're in the mud and one wheel spins and the other doesn't. it will. lock both together to get out out and the once you do like 25mph, a different set of weights force it to unlock.

sometimes they get sticky. a fluid change with the correct fluid could. help. I suggest that I stop by a gm dealer and buy 2 qt of fluid based off your vin number. as all the auto parts store has some amount of limited slip additive in it. and even those this has clutches, it needs zero limited slip additive in it. because it's designed to lock and unlock. not slip like a posi in a car would.


most people have no issue with auto parts store fluid, but I found a small amount of posts talking about it. and after I used it, mine tried to lock in a parking lot with zero tire slip. so I went to the dealer, paused double the amount per qt. but it has never done it again.

go to youtube and search for g80. there's tons of videos explaining how it all works and what to look for. you probably don't need a new diff, but if you do. guys here get used ones for. under 500$ for the whole axle low mileage used. you can even upgrade at the time. you definitely don't need to sell the truck over this, unless you really just want to. especially having access to a lift. Just having a garage to work in is more than most diy guys have access to.


I guess I should ask if the dash is flashing traction control or stability control active while the rear is locking. that could be totally different if it's applying the rear brakes

no dash lights on. in the past I'd get a service stabilitrak message, it needs a wheel speed sensor, which I have already bought. but it went away once I put new pads on.

 

[swathdiver]

Check your brakes, make sure they are not causing the wheel hang up.

Then you ought to take off the rear differential cover and have a look inside. Post up pics and the fellas here can help with that.

Your center section may need new clutches, it's less expensive to just replace the entire axle with a used one, easier too.

 

[Joseph Garcia]

If you need to replace the axle, you can get a used one from LKQ for under $500 delivered.

 

[89Suburban]

Check your brakes, make sure they are not causing the wheel hang up.

Then you ought to take off the rear differential cover and have a look inside. Post up pics and the fellas here can help with that.

Your center section may need new clutches, it's less expensive to just replace the entire axle with a used one, easier too.

Maybe he has a parking brake that is hanging up or the lining broke off and is jamming up in there

 

[salisburyv]

I jacked it up and put it on jack stands. I started it and put it in drive and slowly took my foot off the brake. both rear wheels spun, no locking up of any kind. I stuffed the brakes, applied them slowly, no lock up. put it back on the ground and went around the block and the left rear wheel was locking up, still.

So, my plan is simple, I already pulled the sight plug, it was about a 1/4" thick no chunks, just metal mush. The fluid is pretty close to black. I had it changed about 35000 miles ago.
But now I'm even wondering if it got done. I'm going to drain the fluid, remove the cover and inspect. (I'll take pics of the innards) I picked up A Felpro diff gasket and some blue rtv to hold it in place , 3 quarts of Valvoline 75w90 synthetic (with no modifiers added) . I found it takes 2.25 Qts. I was going to fill it till it starts oozing out. And then take it around the block and pray it's fixed. I'll report back. thanks guys!

 

[B-train]

Buy a can of brake clean as well. When you get the diff cover off, give everything in there with a good wash and let all the fines and particulate clean out. Let it air dry for a bit and then reassemble.

 

[j91z28d1]

if. you have the nice rubber factory cover gasket. I reused mine and it seals great. don't know what fel pro is, but if it's not rubber. might just reuse them oem one and skip the rtv mess.

 

[salisburyv]

Hey fellas. Day off today, so I ventured up to my in laws. He's got a lift, and I was able to use some power tools to remove the cover and take a peek. 1st, the fluid was black, the magnet inside the cover was coated in nastiness. Worse news, appears the spider gear housing has a nice crack in it. I cleaned the inside of the cover and wiped out the diff as good as possible. once I saw the crack my heart sank. But, my father in law asked me if I wanted him to weld it. I figured it couldn't get any worse, so I let him. he tacked it in a few spots, and then on the longer flat section he put a bead. I'm not a welder, but it looks like it should hold. I only need another 6 months with this truck and then I'll be in a better position to get another vehicle. (I have 5 payments left). not sure if the weld will hold, but I drove it back home and it still seems like the left rear is locking up (kinda reminds me of a posi that kinda hops when turning left. let me know what you guys think. I had the rubber gasket on there, so I just cleaned it and put a light bead of RTV, and encircled the bolt holes. no leaks.

 

[89Suburban]

Hey fellas. Day off today, so I ventured up to my in laws. He's got a lift, and I was able to use some power tools to remove the cover and take a peek. 1st, the fluid was black, the magnet inside the cover was coated in nastiness. Worse news, appears the spider gear housing has a nice crack in it. I cleaned the inside of the cover and wiped out the diff as good as possible. once I saw the crack my heart sank. But, my father in law asked me if I wanted him to weld it. I figured it couldn't get any worse, so I let him. he tacked it in a few spots, and then on the longer flat section he put a bead. I'm not a welder, but it looks like it should hold. I only need another 6 months with this truck and then I'll be in a better position to get another vehicle. (I have 5 payments left). not sure if the weld will hold, but I drove it back home and it still seems like the left rear is locking up (kinda reminds me of a posi that kinda hops when turning left. let me know what you guys think. I had the rubber gasket on there, so I just cleaned it and put a light bead of RTV, and encircled the bolt holes. no leaks. View attachment 474061

DAYUMMM!!!!!

 

[strutaeng]

Yikes! Never seen that before. The differential carrier itself cracked...

But based on your symptoms after the welding, I'm going out on a limb, and say the cracked carrier is probably the "effect" of something wrong. Possibly spider gears seized? Not the cause. IDK?

I'm guessing you didn't try turning the wheels while it was on the lift? I bet something is seized...

 

[donjetman]

I predict its not gonna make it 6 mths

 

[salisburyv]

Yikes! Never seen that before. The differential carrier itself cracked...

But based on your symptoms after the welding, I'm going out on a limb, and say the cracked carrier is probably the "effect" of something wrong. Possibly spider gears seized? Not the cause. IDK?

I'm guessing you didn't try turning the wheels while it was on the lift? I bet something is seized...

oh, I turned the wheels my friend... that's when I could see some of the teeth on the spider gears were chipped a bit. but it didn't get hung up. moved smoothly. now, I'm hearing a humming noise. pitch changes with speed. so, wheel bearing most likely, or the spider gear assembly is making the noise. I've never heard of this before. I do not "beat" on the truck. My wife is trying to say that the 1 time I pulled out and the wheels spun from going over the double yellow line and then it caught traction is the reason. that's not the first time that's happened. she's trying to blame my driving, like she always does. separate issue. But I digress, it's time to start looking for another vehicle. Hard to do when you don't have any money. Hopefully I'll get that 6 months....

 

[salisburyv]

obv, I cleaned all the garbage out and replaced with 75w90 gear lube. no limited slip modifiers. fingers crossed