My son was out driving this past Thursday afternoon, called me at work to say the Blazer is "F'ed up". So what's the problem son? The passenger front wheel fell off, son replies. It's tilted off at a 45 degree angle. OK, so the upper ball joint failed. I called the tow truck, picked up the Blazer and into the shop she went, no problem. Replaced upper passenger side BJ and did a complimentary chassis inspection (with a full printout on their computer system). FYI: This is my local small mechanic shop and they are honest, didn't try to sell me anything beyond the BJ fix, although they noted the front sway bar link was broken. They asked if the Blazer clunked. I said, Yes it does, and had them fix that too. Drove it home Friday, good to go. $340.00, parts, labor and tow, not too bad.

Read the printout, mentioned the leak I was aware of (transmission), but also noted leaks in the steering and the rear differential cover. Ok, I'll tackle these one by one as time permits. Saturday morning, I start with the differential cover, seemed easy enough. Jacked her up, blocked securely, drop spare tire, tried to get differential cover off. Problem #1: The differential cover bolts are 12 mm and they are in there tight, they are also rusted over and it's hard to get a good grip on the bolt heads. Got 9 bolts out with hand tools (much cursing) but could not get that 10th bolt. Finally dragged out the air hammer, tapped a 12 mm air socket on the rusted bolt and wha-la, out she came (some bolts are in places where you can't get a straight shot at so using the air hammer was not an option on most of the bolts). Put drain pan in place, tapped a wood wedge between the cover and the differential housing and let the fluid drain out. Now it's time to remove the diff cover. Gently move the misc brackets (2) that were attached to the diff bolts (one bracket supported the brake fluid distribution block for the rear wheels) and jiggled the cover out of the vehicle. Wasn't gentle enough though, one of the brake lines from the distribution block to the driver side rear wheel ruptured (rusted out) and the brake fluid started bleeding out. Dang! Line to passenger side did not break though, luck.

The diff cover was a rusty mess, and I could easily scrape off the exterior surface of the cover with a putty knife, like I was peeling paint off wood trim after a good dose of Metylene Chloride. Held the cover up to the lingt and could see a pinhole right through. Checked 4 places for a replacement cover, nobody had one, salvage yard was already closed. JB Weld to the rescue. I cleaned the entire cover with a wire wheel chucked into my 4.5 inch grinder, took off all the surface rust down to solid metal, then scrubbed it clean (twice) with degreaser, then soap and water. Dried it real well. Mixed up a good batch of JB Weld and slathered in all over the outside of the cover, until the entire cover was covered, then smoothed it out with my finger. Let sit overnight.

Sunday morning, cover (JB Weld) is hard. Primed and painted diff cover. Wire brushed and painted the diff bolts. Use a thin layer of RTV sealant on the diff housing, then press the new gasket into place, then apply a thin coat of RTV to the diff cover, then jiggle the cover back into position, working around those brackets until everything lines up, then start re-bolting the cover home, alternating the bolt pattern as you tighten so the cover seats equally. I check for the proper torque settings but I trust my hands and my eyes. I know when tight is tight enough, generally. You don't want too tight so you squeeze all the RTV out. Forgot to mention. ALWAYS use ANTI-SEIZE compound on any bolt that you ever remove and replace in your Blazer (yes, even if you never intend to do that job again. The next owner will thank you).

Next, you need to refill the differential housing with 90 weight gear oil (this stuff stinks, literally). Anyway, I looked at the fill plug and immediately though that that's going to be a real bear to get the plug out, so I disconnected the differential vent tube (a rubber hose) and squeezed the gear oil into the differential housing through the connection tube and reconnected the hose. That was easy enough, took some time but probably less than trying to remove the fill plug. I though about rigging a T connection into the vent hose to make a fill-in point but didn't have the right size fittings and abandoned the idea. No more differential leak.

Next step, fix that brake line. Having never done brake lines before, I learned a lot. It's not really that hard to do, but bending new brake lines around all the obstacles was a real PITA. Working slowly and carefully will yield good results (but your thumbs will ache for a little while). The brake line fittings are standard 3/16" threads and you will need a flaring tool if you cant get the brake lines the right length. I could not so I had to cut and flare my own. Not a big deal, thankfully AutoZone had the flaring tool I needed to do this one time job. Finally, don't forget to bleed the brake lines to get all the air out. I was surprised at how dirty the brake fluid that came out during the flush was.

I replaced the driver side upper ball joint this weekend too, while I was already completed dirty from working on the differential. That's a fun job, too.

 

A job well done! I have definitely been there before. At least you had air tools to replace that ball joint!

 

Thanks.

Surprisingly, I didn't really need or use the air tools for the ball joint job. I ground out the rivets with my 4.5 grinder, punched out the rivets, then hand hammered a cold chisel and a pickle fork between the A arm and the BJ until she let go. I was being gentle at first, but eventually got frustrated cause the BJ wouldn't let go. Getting a bigger hammer (3.5# baby sledge made all the difference), a couple good whacks and the BJ let go (it's almost a violent release but it's oh so satisfying when she finally pops out of there). Putting it back together was a breeze.

For those who haven't had the pleasure (but may try this job): some basic info
1) existing ball joint castellated nut was 7/8" wrench size. An offset box wrench fits in there nicely.
2) digging out the cotter pin can be tricky. I broke off the legs as close as possible to the nut, then punched out the rest with a pin punch. I could not hook the cotter pin loop since it was recessed into the nut
3) loosen the stud nut but don't take it all the way off. Leave it partially on while you beat the ball joint out so the steering knuckle doesn't flop out when she finally breaks free
4) clean up the A-arm surface mounting area for the new ball joint so you have a nice flat mounting surface for the new ball joint
5) installation is the reverse of removal now
6) don't forget to fill the new BJ with grease. You'll know she's full when grease starts extruding out of the rubber bladder (the rubber bladder gets plump)

Air tools (mine anyway) do have their limits. My hammer didn't have enough ***** to break the driver side front sway bar link free (shop replaced the passenger side, so I figured I'd replace the driver side. I like to always replace parts in pairs if I can, more for peace of mind than anything else. I gave up after 10 minutes of hammering on the sway bar link. Oh well, fingers crossed).