Blown rear differential?

[mrjean]

so today i was going around 65 on the highway just cruising when all of a sudden i felt like a pop or like i ran over something. i pulled over and my abs/brake lights came on and my dash said inspect brake system or something like that. once i stopped the car i could not drive fwd. the engine would move like if the car was braked. i popped it on reverse and it went back about 6 ft before stopping like it hit a wall. i then put it on fwd and it went up like 6 ft and then stopped like if it hit a wall. at this time i had already called a tow truck. i needed to know the mile marker so i had to drive up (8degree weather today without the windchill). i let it cruise on drive and slightly applied the accelerator and the car went ahead with no problem. i never accelerated more than 5mph. once i got to the marker i stopped and turned the car off. the flat bed showed up and popped the car on top. once we got to the shop he let it down. turned the car on once it was down and went to park it on the sidewalk and all i heard was clunking fwd or reverse. it didnt move. had to move it on neutral. didnt see anything underneath the car to indicate fluid until i was picked up...GREASE UNDER THE DIFFERENTIAL!

about a month ago i had the car go to the shop for a loose transmission hose and he reminded me (from summer time) that the SEAL for the Differential Drive Pinion Shaft Bearing needed to be changed since it was spraying grear up into the top of the differential. he had to fill up the differential with grease.

now that i told u my story, is it a blown differential?

if it is, im going to go ahead and probably get rid of it. i cant keep fixing the little things that keep breaking on this. ive put way to much money into it already. its an 02 so i know it needs maintenance, but ive changed the whole frontend (suspension) and just cant keep going.

 

[blazinlow89]

Sounds like it could be, but the only way to find out would be to pop the rear cover off, or remove the fill bolt in the front and take a look inside. Its hard to judge though based on the description given.

When the rear went in my blazer it was a horrific jarring experience that started as a ticking sound. Thought it was a hung brake shoe or something. Kept driving and it went from a tick to a tapping that increased with speed and you could feel in the truck. By the time I made it another 4 miles to my uncles house it was now a knock that felt like the truck was going to fall apart everytime it made the sound. Going up the hill to his house was the end of it, every few feet was a loud jarring sound that shook the truck with a lot of force. I would equate it to riding a bike and hitting a stick every time the wheel goes around, going past the stick and hitting it again.

After I pulled the cover off I found 3 teeth missing off the pinion gear and a nice soup of metal a diff fluid. The only thing I would say was different is that I was not able to move when the sharp jarring occurred.

 

[IllogicTC]

Your best bet is as described above. Remove the rear cover and inspect. I'm not sure that grease is really the proper term, it's 75W-90, if he used grease that could affect the system. I know I'm being nit-picky, probably just the term picked to explain what was found

But I'm also curious as to why it set off the brake system warning, and you just had one pop. Since the differential assembly is spinning fairly fast at 65MPH, you'd likely experience repeated pops or grinding, clunks or whining the entire time you're moving.

Before you go actually digging into the differential, it'd be worth simply checking the brake reservoir (quick, easy and free!). If it's empty, or low and has dark fluid like what you'd seen on the ground, we may have a different culprit.

Try here, read through the symptoms and see if any applied to you during your scenario.

 

[blazinlow89]

^ true, it could be the parking brake assembly destroying itself. Diagnosing is difficult without having the vehicle in front of us, some things are easier than others. Assuming the rear diff is a good place to start, however there are more components that could cause similar issues.

 

[IllogicTC]

I'm thinking quick check of the brake system, if it all looks okay then time to break out the tools and get into the differential. I was choosing to check the easiest things first

I didn't even think of the parking brake assembly, I'm not sure that it'd involve spattering grease on the ground but who knows? Inspecting the system yourself is, again, free, and free is a nice price to pay.

 

[blazinlow89]

I didn't even think of the parking brake assembly, I'm not sure that it'd involve spattering grease on the ground but who knows? Inspecting the system yourself is, again, free, and free is a nice price to pay.

OP did say that they had a pinion seal leak.

 

[IllogicTC]

OP did say that they had a pinion seal leak.

Yeah, I guess ripping her open is probably needed either way.

 

[mrjean]

just came back from the shop...the rear axle cover has a hole the size of about a half dollar coin. spilled all the oil. so yea assuming the differential.

i am looking to see which one i have, the junk yard needs to know the ratio.

 

[C-ya]

just came back from the shop...the rear axle cover has a hole the size of about a half dollar coin. spilled all the oil. so yea assuming the differential.

i am looking to see which one i have, the junk yard needs to know the ratio.

Look in your glovebox. There should be a list of RPO codes. Get all the G codes - one of those should tell him what he needs.

 

[blazinlow89]

Sticker in glove box, you will see GU6, GT4, or GT5, 3.42, 3.73 and 4.10 respectively.

See if you can get pics, it may help another member in the future. Besides carnage pics are always welcome.

C-ya makes a good point, make sure you tell them if you have code G80 as well.

 

[mrjean]

ill go back tomorrow and get pictures of the cover for you

i just told the shop (i had to leave and go to work)

 

[mrjean]

if i have the vin, can i find it anywhere?

 

[blazinlow89]

if i have the vin, can i find it anywhere?

VIN does not contain that info, a dealer could run the vin and possibly get a build sheet with that info. However that is not always a definite.

Here is a pic of the service parts list. All 3 digit codes.

 

[mrjean]

glove box sticker
View attachment 32359

 

[blazinlow89]

GU6 in the second row indicates a 3.42 hear ratio with no locker.

 

[mrjean]

does it matters whether it comes from a long or short wheelbase? or v8? or year? i thought i read somewhere here that it didnt matter..dont know how true that is.

 

[blazinlow89]

Yes, the SWB has a smaller rear diff. The EXT rear is 8.6", vs the 8" in the SWB trucks.

 

[mrjean]

oh but of course lol. i found a swb for 100 and a lwb for 150. kind of thought i would have gotten away with it. the shop is charging me $350 to change it.

no my question, will the seal at the shaft usually be included? obviusly if the seal is broken, id want to change it.

btw, its #32 in the graph
View attachment 32369

 

[blazinlow89]

Are you buying a used dif, or just the gears. If you buy a used dif it should come with just about everything but the brakes and possible sensors etc, so all seals would be intact (you would assume). If thats the case you might as well buy a rebuild kit which is usually under $100 (depends on rear and brand, dont go cheap), which should include new seals, and bearings.

If buying just the gears, then a rebuild should be done anyways as they have to tear into it anyways to install the gears.

$350 is not bad if that includes rebuild for either new gears or full swap, if its just to put a used rear in I would find another shop. A used dif should always be inspected thoroughly anyways, and it is much easier to install seals and bearings on a bench, vs being installed in the truck.

Find out what the $350 entails, and what the $150 is actually buying.

 

[mrjean]

The $150 is for a whole rear axle assembly of a ext with 50k miles on it.

So to swap the axle assembly for 350 is too much?

 

[blazinlow89]

Without a refresh I would say so. However it has been a while since I have had to deal with pricing for a rear dif swap. Maybe another member can chime in who has had it done recently.

 

[Aries]

The $150 is for a whole rear axle assembly of a ext with 50k miles on it.

So to swap the axle assembly for 350 is too much?

I don't thinks so. First off most EXT GM 8.6 3.42 ratios are running $200/250 around here and that's with you pulling it. Second: Shop hourly rate can run $90 to $125 hour and I know places that charge a lot more and go by book time. How much effort and labor is involved on your end?

So your having a blown rear replaced for 5 Ben's. (blown rear out, replacement in, you drive off) Not bad IMO.

 

[blazinlow89]

I don't thinks so. First off most EXT GM 8.6 3.42 ratios are running $200/250 around here and that's with you pulling it. Second: Shop hourly rate can run $90 to $125 hour and I know places that charge a lot more and go by book time. How much effort and labor is involved on your end?

So your having a blown rear replaced for 5 Ben's. (blown rear out, replacement in, you drive off) Not bad IMO.

Put that it doesnt sound too bad.

I am looking at it from the backyard mechanic view point, 4 bolts for the control arms, 2 bolts for the U-joints, 1 bolt for the pan hard bar, 2 bolts for the end links, 2 bolts for the shocks, and 6 lug nuts for each wheel. Then you have 2 brakes hoses, the parking brake lines some bleeding and sensor hook up. All that and its not like the old leaf rears that required some wiggiling to get it nice and square, although you should still check. 2 hours tops for a couple of guys and some beer.

The last rear I had done was about $300 for full tear down and rebuild. That included some parts I did not order like new axles, dif fluid an the modifier, as well as the seal kit. Price out of pocket for me was well over that, but I also had it built to handle 600 hp, without issues.

 

[mrjean]

as promised...blown differential pictures...(also for some reason the leaking of the oil around the wheel got worse after this so yea time to change.
pictures were taken as soon as he removed the cover for the differential.

PS.
leaving the shop, 10 blocks away the transmission failed. drive, 3 and 1 are completely gone...2 works barely. heard a clunk, then acceleration with no speed and finally no movement. i cannot catch a break...looking at $500 for a tranny with 146k on it and 450 to put it on (well 225 for the mechanic).

View attachment 32396
Shavings inside the cover
View attachment 32397
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View attachment 32400
View attachment 32401
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View attachment 32403

 

[blazinlow89]

Looks like a grenade went off.

 

[IllogicTC]

I'd bet the actual stresses induced by the differential going, or attempting to drive with the bad differential, may have something to do with the transmission.

 

[The_Roadie]

Looks like a grenade went off.

That's why it's called "grenading" the differential.

Here's a picture of the "fine grind" in the bottom of mine after I had to limp down off a mountain 20 miles to get back to pavement using FWD only.

 

[IllogicTC]

It's like a robot took a dump in the pumpkin.

 

[mrjean]

wow ROADIE!!! thats horrible...
i think for me the insult to injury or the sault of the wound was that my wife drove off in my car while i paid the mechanic for the labor (i was driving my other trailblazer) and as soon as i signed the damn CC slip she calls me that the car stopped responding or was slipping. i told her to stop and me and the mechanic went to meet her. he pulled up to the shop on 2nd. said Drive and 3rd dont work and the transmission doesnt even go into 1st.

so lets recap...
184 for the rear axle assembly
320 labor
500 for a 146k tranny
450 labor
=
one pissed of JEAN (ME)!!!
thank you come again...

tranny will be at the shop on friday (HOPEFULLY)...anything i should look for when he takes it off? not sure i will get to see the same carnage as this one.

 

[blazinlow89]

Pun was intended Roadie .

I remember reading somewhere a while back about solenoids causing issues. If I have time later I will post the thread.