Hey guys,

Couple quick questions:

First off, how does one determine how good a rear diff is in the Blazer? I've never owned a truck and I want to do at least a basic inspection of it for my sister in her 'new' Blazer. Obviously one could say "Does it go into gear?" and "Does it move OK in 4WD?" but I just want to know if there's something further, or if that sums it up.

Second, and probably necessitated by the first anyway, what kind of oil/lube does it take? The other thread below says just under 2qt of 80w-90 or 75w-90? Is that the same as manual transmission LUBE (not ATF), such as is used on my Corolla? It has a 75w-90 rating on it, but I don't know if it's a different type or what have you.

Third, anything else I should be checking? Common wear parts, etc? The other thread mentions to look at the magnetic drain plug because that will have any shavings and such if there's trouble, but beyond that? I'm just thinking simple stuff. This car was already promised to last her only a year anyway, so I'm planning to have it hold on that long, then, depending on what happens, maybe make my own offroad toy afterwards.

I found this thread which covers the basics of removing the cover and stuff, but I just need to know specific advice to my questions:

https://blazerforum.com/forum/showthread.php?p=337913

EDIT: It appears that the bolts are pretty stuck in place. I hit them a full hour before I tried to pull them out with penetrating oil to no apparent effect. I'll have to put this sucker up on jacks and yank the wheels and see what I can do with a breaker bar, but as of right now, that has to wait for me to get a new set of jack stands, and more energy. Advice is welcomed, however.

I looked at Autozone's website and I can say for certain that it's a 7 5/8" ring gear if the pics are accurate on their site. The cover is more ovaloid than the rounded one shown for the 8" ones. Link below:

http://www.autozone.com/autozone/cat...&parentId=12-0

 

1) I'd put the rear end up on a couple of jack stands and with the tranny in neutral (front wheels blocked of course) rotate the wheels one at a time and listen for any unusual noises (like grinding, chattering, etc.)
2) Hate to tell you this if you're like everyone else but your Owner's Manual is a real good source for information on what your truck takes for fluids, light bulbs maintenance intervals, etc. Use what it says to use. Yes it's gear lube. 80W-90.
3) These rear ends are pretty reliable. If you don't know how many miles since the last fluid change, I'd just do it. You can get a pretty good look at your ring and pinion to see how they're wearing at that time. Just drain the fluid and wipe out what you can. I don't like to use any cleaners in there (personally) because you aren't going to get it all out.
If your sister was told the truck would only last a year I'd be a little more concerned about other things than the rear end. It's probably the most reliable thing on the truck unless it's been really thrashed and abused.

 

Gotcha Gimpy... Sorry I didn't mention, just in regards to #2 - I don't actually have an owner's manual! :P

Seriously, the people she got this thing from trashed it pretty good inside, and that appears to have included using included paper products for unorthodox uses. I would've hoped that one of them would've included "trying to start a bonfire under the car" but apparently that escaped their attention. It would've put this poor thing to a proper funeral instead of the abuse it took.

EDIT: As to the reliability, before I sprayed it down with penetrating lube and the surrounding casing with engine degreaser, I noted only small areas of bleed/leak evident, around the bottom. While you're right, I should worry more about the engine/trans, I can't do everything. Basically, my idea is to protect the rear end and fix simple things that I can do that could also be problems, so that if they're not broken, they stay that way, and hopefully it also lubes things up and gets them back up to spec.

Engine/trans wise, I'm going to have her "friends with jobs" do a complete fluids flush, and I'll make sure they add a couple bottles of seal restorer and oil stabilizer, etc. This way, if she is having problems, it might help to shore them up.

Essentially, if this thing could be dead again in, say, a year, and sitting in the driveway waiting for me to transform it, then I'd rather not have to replace or rebuild a tranny AND a rear end. Plus, that also means that any other work I do, I potentially reap the benefits of. And what the hell, if I wind up actually finding and fixing problems and the car does stay on the road for a couple years or more, well, so much the better and my sister doesn't need to buy a new car between now and then. Hell, maybe she'll even want to offroad it, at which point I'll send her here, get some ideas going, and then help her build it out.