front grinding/rumbling noise

[billzie]

Ok, first I'll apologize if this is a premature post but I'm trying to get input in all phases of trying to figure this out, here goes...
First off, I knew front brakes were going/squealing, the rears were toast and those were replaced a month or so ago and just didn't find time to do fronts. I had to tow my little Merc Tracer from my old place, it sat for a few years on gravel and not running so had to engage 4hi and tow it out of the settled spot. Front brakes locked up on Tracer, rears freed, so when I eventually got it on the tow dolly I headed home. 1 mile to highway. Then about 4 miles down the road at speed a loud grinding/rumbling noise happened all of a sudden. I pulled over immediately. No spills, no noticeable breakage, but when back in truck I noticed I forgot to put back into 2hi, I put in 2hi and hear and felt it disengage. I headed back home, the noise was still present but not as loud and I kept my speed much slower.
I thought for the best that maybe a brake part or gravel was lodged somewhere because it sounded like it was coming from the front drivers side. The next day I do the front brakes. I don't notice any parts hung up or any gravel stuck. The wheels turn by hand but having never done it before on this truck I don't know how freely they turned, but I did not notice any noise or "catching". Also, the last 1.25 miles getting home is up a steep grade that I'm now having very poor power to get up as if calipers are froze.
Side notes: the parking brakes are non-functioning and those need done so those aren't a culprit, I have a P0440 code and will be looking into that as well today and this weekend, I've had the 03 TB EXT about two years/30,000 miles (has 150K total) I have no clue about prior maintenance but I've done plugs, cleaned throttle body, air filter, oil changes alternator; also I am very cash poor so I'm looking at the least costly options for diagnosis and repair but willing and able to do most repairs myself granted I can figure out the problem.
Thanks in advance for any and all help! Bill.

 

[linneje]

From your description it sounds like your front differential. By removing your left front tire, you can get access to it. You didn't list changing the diff oil, so you can crack the top fill plug first (I can't remember ... is it a 19mm socket required?) then the bottom drain plug which I think I used a 3/8 inch socket extension. Drain and see what comes out. If you get debris it would confirm damage to the diff.

Fill with 75W90 gear oil - your owner's manual has the capacity.

 

[billzie]

Thanks for that info. I actually didn't get to check it yesterday, just way too much on my to do list. I hope I can get to it today with the good weather. I'll also follow the checklist stickied in this forum. Thanks again, Bill.

 

[billzie]

Well, my back and knees wouldn't cooperate with me so I never got a chance to look at the problem, but I did take it to a local shop I generally trust. They said it was "dry" of gear oil most likely really really low, metal in the fluid, so based on my description and what's seen they figure its probably beyond a rebuild. They drained what was in it, "flushed" it with 2 can of brake cleaner, and started topping it off. It stated pouring out of the L side shaft seal. I went about my day, grinding worse in the first 15 mi or so, sat for a few hrs then was quited down to prior to the shop having it, i figure any bigger bits settled. That seal had no active sign of leak, so this may have been a problem since I bought it, I think it's been in AWD once for a few miles and a hand full of times in 4hi just to get out of my 40' driveway. That one time when the noise happened is the only time I've had it engaged for more than 40-50 ft and over 10 mph.
Is it possible the gear oil has been low all this time?
So far they're quoting a reman with 3yr/100k warranty installed at about $3,000!

 

[The_Roadie]

Sorry for your troubles. Many owners don't realize the differential has many moving parts inside even in 2WD mode, driven by the driver's side CV shaft. And checking EVERY fluid level is critical whenever you buy a used vehicle. Changing front and rear diff oil at 100K is also essential, and even more important is the transfer case fluid EVERY 50K (not 100K).

One cheap way out is to remove both left and right CV shafts and only use it in 2WD mode. Front diffs can be had from the recyclers and Ebay vendors for $400-500 max.

Maybe your shop is looking up costs for transfer cases and not differentials? I'd be carefully checking the transfer case and transmission fluids right about now as well. And changing out the coolant, power steering and brake fluids while you're at it if you didn't do those at 100K.

 

[billzie]

Thanks Roadie for replying.
Actually the used dealer I bought it from let me take it on an extended test drive, 4 hrs, and I brought it to this shop to get checked out because I generally trust the owner (a drag racer) and he has an Envoy and he turned me on to this and the OS. I was in the bay for most but not all of the inspection, he might not have checked those fluids. Other than some suspension/steering parts, he said all seemed to be in good shape, I was able to see that it had been in some relatively minor accident with repaired/replaced body parts (front bumper, DS fender) which is common here in rural Appalachia with deer, but accidents didn't show on carfax. Oh well...
Anyway, the quote so far is for a remanufactured front diff with 3yr/100K warranty, he said it is about $ 1700 of the estimate with about $800 in labor and the rest in incidentals and oil pan reseal. So I figure whoever they are getting the diff from the shop has to get their markup on it, so maybe the diff is about $1200-1400 plus the shop markup and that's not far from ones I've seen on ebay for reman units. Still sucks.
I generally am capable of doing this type of diagnostic and rem/repl work, but the body just doesn't cooperate all the time. Also, I'm willing to try and rebuild it IF it can be rebuilt and IF there aren't a lot of specialty tools needed. I know I don't have dial gauges or good mic set if those are needed. I do have a 50 ton air/hyd shop press but it's been a few years since I last tried to use it and I think the cylinder needs rebuilt (living in rural appalachia doesn't make for easy access to fix stuff like this). A lot of search/research for me looks like which is fine because I don't have the cash to do much now, next month I might be able to swing a rebuild 'kit" I saw on RA for less than $200.
Roadie, any advice on things to look for upon tear down? Also, can I run without diff while I have it out for repair. I just don't have the $ for a shop repair regardless of a reman, JY, or they rebuild, or a reman and I install. Oh, they also said I have a rare ratio and the 3-4 JYs they deal with did not have it, 3.73
Thanks again, Bill.

 

[The_Roadie]

Ebay has more than 7 3.73 diffs for $300-550. I wouldn't even begin to collect the tools and skills to rebuild one for that little. We have multiple folks who have replaced theirs on offroadtb.com with threads including pictures. Nobody has to remove their oil pan unless you believe the dumb Haynes manual instructions. Many Ebay vendors seem to call it a "front carrier" not a "front differential" so that may help your search.

You can certainly run without the diff. It's not a structural part, since 2WD trucks do it all the time. Engine oil won't drool out the intermediate shaft hole because the 2WD engine uses the same oil pan and there's a tube cast into the pan for the intermediate shaft. That way the engines also use the same amount of oil (7 quarts).

4.10 is the really rare ratio, but all the SS came with them.

 

[billzie]

Ebay has more than 7 3.73 diffs for $300-550. I wouldn't even begin to collect the tools and skills to rebuild one for that little. We have multiple folks who have replaced theirs on offroadtb.com with threads including pictures. Nobody has to remove their oil pan unless you believe the dumb Haynes manual instructions.

Engine oil won't drool out the intermediate shaft hole because the 2WD engine uses the same oil pan and there's a tube cast into the pan for the intermediate shaft.

4.10 is the really rare ratio, but all the SS came with them.

What I was referring to was my quick ebay search looking for comparable "remanufactured, warrantied" front diffs, and those seem to be in the $1000 range.
I have quite a few tools considering I have never worked as a shop mechanic. I pick up things at yard/garage sales and estate auctions; I've been lucky, there's a dealer mechanic near me that does a spring clean up every few years and when he has his garage sale I'm there early and score weird stuff like odd attachments for hammer pullers/drivers and custom fab stuff, also here in rural appalachia you get a lot of useful/weird stuff at estate auctions from farmers and miners and such. Did I mention the 50 ton air/hyd shop press? LOL. I just don't have a lot of store bought specialty tools (especially considering that before I moved from Chicago I was wiped out twice due to break ins of my garage). Oh, and I've rebuilt a manual Nissan truck tranny and an auto Ford Escort GT tranny, AND I have the GM shop manuals too if that helps.
So, unless there's some really specialty tools involved or no way for me to judge its not salvageable, I might "have" to try a rebuild as the kits I see on RA are under $200 or about half of what those used diffs on ebay are going for (oh, plus s/h).
The more I'm reading here the last week or so, I'm gaining a lot of knowledge, THANKS everyone! There's a lot of misconceptions about this platform out there, the local JY won't separate a front diff from engine for our platform because of the perception that the oil pan is inseparable or something from the diff. Alas, not the right ratio anyway.
I was just repeating what the shop said, that I had the "rare" ratio, maybe he shouldve said "rarer" ratio? EXT and XL are rarer I assume than most others. 3.73, no wonder mpg sucks, no matter what I've tried, the best I've gotten was about 16 mpg on a all highway road trip.
Oh well...