4x4 problems with front differential

holytornado84

Registered Member
Original poster
Feb 21, 2013
111
Hello to all the fellow GMT users on here. I am new to forums but think I have the gist of it. I have recently been having trouble with my 4x4 not engaging in my 2004 trailblazer. Switch it over to 4hi and the actuator and transfer case whirring sounds are present and the indicator light switches to 4hi and stays lit up solid. Jacked up all 4 wheels and switched to 4hi and had someone let met get a look at the front drive shaft and it is turning so I figure it is not the transfer case. I also noticed a while back that the differential has a leak somewhere and have added fluid a few times. Since I have owned the vehicle I have driven it around 85k and the odometer now reads 183k. I have not had 4x4 for around 20k now. Now that I want it fixed, I check the front differential and it seems to be pretty dry (could barely find fluid in the bottom). Before the 4x4 problem happened I would switch over to 4x4 stuck in sand and accelerate but the back wheels would continue to dig for a few seconds, then the front wheels would kick in after a big noise (grind or thud) in the front end and run smoothly after that. I also checked the sides of the differential casing for metallic material and found that my finger was sort of glittery.

Since then, I have been looking for a used front differential and have found one for a 2002 trailblazer. I was wondering if it would fit my 2004 or if I'm even heading the right direction? Thanx for all the useful info.
 

Sparky

Moderator
Dec 4, 2011
12,798
Hi there!

The thing to make sure of on the differential is the gear ratio. This is very important to get correct or you'll bind up the drivetrain! But before you assume that it is the cause (those front diffs are a bear to replace) check the disconnect on the passenger side. They are known to have issues because of a poor design (using grease instead of gear oil for one thing). Make sure there isn't any slop where the CV axle tripot goes in for example. Common failure is the outer seal gets dry, goes bad, lets in crud, which then screws up the outer bearing, which causes a chain reaction that gradually can cause the whole thing to internally come apart and no longer engage.

Sounds like you still have a front diff issue from wear, but usually diffs are quite apparent when they completely go bad as they make really bad crunchy noises and you can see busted gears inside through the fill hole.
 

navigator

Hobbyist
Dec 3, 2011
504
if I were a betting man I would say your splinned disconnect is the cause.
I think if your front diff were bad you would see more signs other than it not working.
The splinned disconnect is a pretty common failure item in our platform.
 

The_Roadie

Founding Member
Lifetime VIP Donor
Nov 19, 2011
9,957
Portland, OR

holytornado84

Registered Member
Original poster
Feb 21, 2013
111
Thanks everyone for your help. I am looking into tearing down the front axle disconnect and replacing the necessary parts if needed. Just waiting for a warmer day. I think it might be that shift fork? Does anyone know if there are any seals or parts in there that it might be necessary to replace (because of opening the housing) upon any maintenance to the axle disconnect?
 

Conner299

Active Member
Jan 16, 2013
279
There are three bearings and two seals that most people replace, when regreasing their disconnect. Refer to THE Roadies post earlier in this thread. Its show the schematic of the 4WD disconnect, and gives part numbers for these. I priced the bearings and seals out at a little over 60$ last time I checked. If any other parts are broken, as well, that's a horse of a different color.
 

Sparky

Moderator
Dec 4, 2011
12,798
When I did mine I did the two seals, the bearings, and the thrust washers (those are cheap).

If you pop it open and find you need a fork, don't shell out the $100 or whatever ludicrious amount they want for one. I'm pretty sure I have a spare used fork and collar still sitting in a box.
 

holytornado84

Registered Member
Original poster
Feb 21, 2013
111
I want to thank everyone for all of the helpful info that I have received on this forum. I finally had a couple of warmer days come along as of last night and began tearing down the front passenger side. Got all the way to pulling the CV axles out of the disconnect and they would not budge. So I started unbolting the disconnect itself to try to pull them out still in tact and it will not budge at all. I am pretty sure that I took the four bolts out that hold it on to the oil pan and stuck a crowbar in between and pryed with all of my weight and it still wont budge. So after all that I shot WD-40 on and in the bolt holes and am going to get back to it in the morning. I want to see if I have loosened anything. Any thoughts on what could be making it not move at all?
 

Sparky

Moderator
Dec 4, 2011
12,798
I used a prybar between the CV tripot and the housing and smacked it with a larger hammer to pop the CV axle free.

The disconnect fits rather tightly in a 1" recess in the oil pan, both are aluminum... yeah see where this is going? They tend to corrode a bit and stick together. Be careful and don't bust yours like I did mine. You need to get something to break down the corrosion behind the disconnect, not just around the bolt holes. Maybe heat on the oil pan directly around the disconnect, but not heating the disconnect itself? But the oil inside the pan may wick away the heat.

Maybe others will be able to help with removal who have run into this and successfully gotten it apart without breaking it. I brute forced mine and that didn't turn out so well :crazy:
 

holytornado84

Registered Member
Original poster
Feb 21, 2013
111
I have been trying to pry the disconnect off from the bottom side in between the oil pan and the disconnect housing. After beating the bottom a bit with a big hammer, I have gotten the disconnect to somehow twist a couple of millimeters to where i probably could not get the bolts back through the holes that hold it on the oil pan. However it seems to stay very tightly snug to the oil pan. I have also not been able to remove the CV axle out of the disconnect as well. I even tried to pull it with a come along as well. Going to do some more thinking on what the next step could be. I am stumped as of now :confused:
 

v7guy

Active Member
Dec 4, 2011
298
first you gotta get that cv out. The splines corrode since no gear oil really gets to that side. Accordingly it's a bear to get out. I used a piece of rebar and a small sledge hammer and beat on the tripot ( the housing of the cv by the disconnect). it's got flat spots you can get the rebar on and then you beat on the rebar. eventually it pops out.
after that I would keep working on the disconnect. if you've twisted it you're going to have to take it out instead of separating the halves and replacing the outer seals and bearings. I snapped mine, as have a lot of other guys, so be careful.
you may try draining the oil and heating the pan up with MAPP or an O/A. good luck
 

Sparky

Moderator
Dec 4, 2011
12,798
If you got it to twist that may actually be a good thing. May mean it isn't totally frozen in there. Try doing a back and forth twisting, spray some stuff back in there some more, twist some more, etc to see if it will come free.
 

navigator

Hobbyist
Dec 3, 2011
504
v7guy said:
first you gotta get that cv out. The splines corrode since no gear oil really gets to that side. Accordingly it's a bear to get out. I used a piece of rebar and a small sledge hammer and beat on the tripot ( the housing of the cv by the disconnect). it's got flat spots you can get the rebar on and then you beat on the rebar. eventually it pops out.
after that I would keep working on the disconnect. if you've twisted it you're going to have to take it out instead of separating the halves and replacing the outer seals and bearings. I snapped mine, as have a lot of other guys, so be careful.
you may try draining the oil and heating the pan up with MAPP or an O/A. good luck

yup, I had to drop the oil pan skid and I used a wooden 2X2, a couple taps with a small sledge and it popped right out.
you can't pull it out, the boot is the only thing holding it together.
 

holytornado84

Registered Member
Original poster
Feb 21, 2013
111
Ok, so I can tell that the problem is the CV shaft is stuck on something because I am able to move the disconnect out a little when prying from the top. I think maybe the bearings or the gears or both are just grinded up and maybe even scarred the CV shaft to where it is hanging up inside there. I wasn't able to Work on it much because I'm sick, but in the mean time I'm going to sit here and brainstorm on some ideas and devices that I could rig up to use to pry it out. :undecided:
 

keepontruckin

Registered Member
Dec 5, 2011
82
The disconnect is such a mother on these trucks... I've had to do mine a few times, the last time was kinda forced on me while replacing a POS rebuilt CV shaft... my CV shaft was stuck in the disconnect like yours is, and i mean STUCK! Like two full days of throwing everything in the garage at it and it didn't budge...I finally took the disconnect and the CV shaft off together to see if I can tackle it off the truck...I couldn't.... So I took it to the local parts guys and they used a press to press it out...crushed the outer washer into almost a cone shape but everything else was fine.

as for getting the disconnect out...The only way I got mine off the first time was slightly rocking it back and forth with two decent size flat head screwdrivers one on top where there is that flat spot on the back of the case in between the two bolts, and one from the bottom as close as i could get it to the cylinder that actually sits in the oil pan...a little of this and it should pop right off...everyone i've heard of trying to use only one pry bar usually breaks the inner housing of the disconnect, something you definitely don't want to do as there really hard to find.

As a means of last resort see if you can get them off together and see if your auto parts shop has a press, the guys by me wanted like 20 bucks i think...it only took about 10 minutes but there was nothing else i could do...

also when its time to re-assemble, its worth the time to sand down the contact surfaces of the oil pan and the disconnect housing a little, and apply generous amounts of anti-seize :thumbsup:
 

holytornado84

Registered Member
Original poster
Feb 21, 2013
111
Has anyone here ever used an OTC axle puller to pull the axle out of the disconnect? I was searching and found a few tools such as that and even a pickle fork and figured I would ask ya'll.
 

fishsticks

Active Member
Nov 21, 2011
433
Did you already take apart the hub side of the CV axle? If not, unbolt the pinch joint where the upper control arm meets the ball joint. Let the whole knuckle assembly pivot on the lower ball joint and pull outwards on the CV axle (disconnect the clips holding the brake lines). This takes some of the elasticity out of the axle assembly and will help when you pound it out. The hammer (2 lb sledge) and drift on the bell method works best. Hammer towards the outside of the truck.

After the axle is out, remove the disconnect by working the rotation back and forth in the oil pan. I had a disconnect split the inner bearing housing and that's how I got mine out. No extra pieces when I was done.
 

holytornado84

Registered Member
Original poster
Feb 21, 2013
111
So I went and purchased a pickle fork and gave a few good jolts and the CV axle came loose. So now I'm down to the disconnect itself and yet still having trouble getting it to break loose. I can pry against the top of the disconnect and it looks to be free because it moves out a good bit. The bottom side is a different story. It will barely move at all on the bottom. Would it be a bad idea to get a puller of some sort and use the bolt holes on the disconnect for the braces and the end of the intermediate shaft inside the disconnect as the forcing base?
 

seanpooh

Active Member
Jan 24, 2012
461
When I did my 2002 Envoy, I was dreading this job... the fear of the housing breaking into the oil pan which would mean more work. But I had the fortunate luck of it come out pretty smoothly with some effort.

I used a overly large flat head screw driver and maybe a 2 or 5 pound sledge hammer. I was doing this job on my back working on the bottom of the disconnect. I wedged the screwdriver on one side and when I had enough, I wedged the other trying to keep the growing gap equal. It just takes time and effort along with a strong arm and back. It can be done.

I read that people could also use a pickle fork if you get the gap large enough for the pickle fork to be wedged into to equalize the growing gap reducing stress and breakage.
 

holytornado84

Registered Member
Original poster
Feb 21, 2013
111
So after prying and prying from all different angles I broke the disconnect inner housing. Disconnect is off but inner housing and intermediate shaft gear are still corroded in the cavity. I have already placed my order on Amazon for a new one. The shift fork had been sheared off, bearings were gone, thrust washers were missing (probably the metal shavings that I pulled out), gears were worn, and the outer seal was bad (still have yet to see the inner seal). Now to remove the rest of the disconnect that is still in in oil pan. It is so corroded that I can't even tell where the disconnect ends and the oil pan begins.:hissyfit:
 

Sparky

Moderator
Dec 4, 2011
12,798
Ouch, I feel your pain. Been there, done that with mine.

Best I can suggest is CAREFULLY drill holes in the remaining chunks of the disconnect to break it up. Once you get it to break a chunk out of that part the rest should pop free. Just don't drill too deep and go through the pan!

I gave up on mine when I busted it off and had it towed to a shop. The shop drilled some holes in the remaining part of the disconnect housing and after a couple holes it broke in half and fell off the pan.

That gear that is still on the shaft should pull right off.

This is the worst feeling ever when it goes crraacckk and you're left looking at this :hopeless: Not sure how much is left on the pan on yours, but maybe this will help you see where you can drill. Remember the disconnect collar (for lack of a better term) goes into the oil pan recess only about 1 inch, so don't drill too deep and don't go too far oustide of the inner bearing race.

busted4x4pan.jpg

busted4x4.jpg
 

keepontruckin

Registered Member
Dec 5, 2011
82
holytornado84 said:
I have already placed my order on Amazon for a new one.

I'm really hoping they didn't send it via lasership like they did with mine...If they did you'll need these...

Amazon Customer Service: 1-866-216-1072

Lasership Customer Service: (800) 527-3764


Lasership probably looses 9 out of 10 packages...If you go to the link you can read the terrible reviews

Amazon.com: Customer Discussions: Laser Ship
 

Robbabob

Hobbyist
Dec 10, 2012
1,089
Sorry to butt in here, but this thread might be the best place for me to:

On a scale of 1-10 with 10 being most difficult...

How concerned should an intermediate guy be to change the CV axle? I see no issues except with that separation from the disconnect. My fear being, doing more damage than good while trying to save $180; total price for Cardone parts and labor is $305 (quote from Maxi service center to change both sides). '03, so it's 10 years of corrosion.

Thanks in advance!
 

The_Roadie

Founding Member
Lifetime VIP Donor
Nov 19, 2011
9,957
Portland, OR
Changing the CV I'd rate as a 3. You need to buy or rent a 36mm axle nut socket if you're removing an OEM shaft, and the Cardone comes with a 35mm, so you either need to have both sockets available, or reuse the OEM nut. The manual says to use a fresh nut but I never do.

The challenge is just to bash the inner tripot joint out of its receptacle by using a short piece of rebar as a punch. Using wood absorbs a lot of the sharp impact that gets the axle's circlip out of the splined receptacle. The differential side is easier because the splines have been bathed in diff oil. The passenger side is often harder because all that's in the bearing assy/ splined disconnect there is congealed factory grease. Useless stuff. Rebuild the disconnect if you have the time. Use the instructions we always refer to on the Offroadtb.com site.

A 3 pound hand sledge is often enough to get the axle out. Sometimes, people have to resort to a 5 pound sledge. Some folks have reported success using pickle forks at the interface. I never tried this because the wedge shape of a pickle fork WILL impart a bending force and more of a side impact to the assembly. This (IMHO) can damage the splined disconnect housing and the bearings on both sides.

The MOST EXCELLENT tool to do this with is a slide hammer crow foot accessory that I've been meaning to buy for years. I haven't seen it for rent at the parts stores, although they DO seem to loan/rent slide hammers.

View attachment 26769
 

Attachments

  • OTC-7509__08278.1359649724.1280.1280.jpg
    OTC-7509__08278.1359649724.1280.1280.jpg
    7.7 KB · Views: 103
Nov 17, 2012
9,727
I used to beat the #@%\ out of my 4wd, switching to and use of, changed the disconnect assembly with help from old site at 104k miles. My cv slid right out. Took more strength putting it in. But that's my luck
 

holytornado84

Registered Member
Original poster
Feb 21, 2013
111
I just wanted to say thanks to everyone that was a big help in me getting this part off of my oil pan. I finally got it off after drilling several holes in it with large bits. I will definitely apply anti-seize on it before putting it back in. I am in the reassembly process now and will test my truck probably sometime tomorrow or the next day down at the river. I'll let y'all know how it goes. Here are some pictures from the tear down.
 

Attachments

  • image.jpg
    image.jpg
    96 KB · Views: 15
  • image.jpg
    image.jpg
    84 KB · Views: 14
  • image.jpg
    image.jpg
    97 KB · Views: 12

holytornado84

Registered Member
Original poster
Feb 21, 2013
111
Well I tested my 4wd out at the river a couple days back and it is working very well! 4hi and 4lo work perfect and I am so happy to have my four-wheel-drive back. Thanx GMTnation!:wootwoot:
 

TollKeeper

Platinum Donor
Dec 3, 2011
6,711
Brighton, CO
WOW man, The things I get to look forward to in ownership of my XUV!
 

Sparky

Moderator
Dec 4, 2011
12,798
Maybe not. Only some seize up bad enough to break off.
 

Ident876

Newbie
May 4, 2022
2
CT
Just pulled apart my 4 wheel drive disconnect and broke back housing apart thought it was gonna be a nightmare had a friend come over he drilled a 1/4" hole straight up like if your laying under vehicle straight up tight to oil pan stuck a phillips in hole with a big flat head behind it and i had a small cats paw on a bit on top we both wiggled and wrestled 45 seconds layer popped out. I did soak it the night before, morning of and after work with oil but yeah dont be scared drill straight up till you hit the race and do as we did. By the time he got over i had broken almost all of housing off pretty much looked like other peoples pics above.
 

Mooseman

Master Blaster
Moderator
Dec 4, 2011
22,325
Ottawa, ON
Wow, talk about the walking dead thread!

I wouldn't be too keen on drilling the oil pan itself but it could be another option.
 

Ident876

Newbie
May 4, 2022
2
CT
No not the oil pan but tight too it like whatever remaining stub that is sticking out i had about a little over a 1/4" on the bottom and he managed to drill into the remaining disconnect housing and put a phillips in it and pry it out that way. It was not completely broken flush. Anyway if you walk into oil pan a little id have it image its atleast 1/4" or 3/8" more likely no? Expecially there it looks chunky might even be a 1" thick.
 

Forum Statistics

Threads
22,038
Posts
620,760
Members
16,485
Latest member
SilentViper

Members Online

Members Online

Members Online