Front diff click

JLS81 · April 24, 2020

I'm new to the forum. I could've done this wrong. But I have a 2010 silverado z71with 107xxx and I noticed a scraping sound between 25-45mph. I jacked her up and took the front driver's side wheel off to check for splash guard scraping or brake pads or a hub bearing. None of that was an issue, no slop in the hub and I couldn't get it to make the scraping sound. I did, however, get a loud clicking noise when I spun the hub. It didn't come from the hub bearing or CV joints but the diff case. I put the wheel back on and put in 4H and back into 2H to make sure I wasn't partially engaged. It still clicked and I tried the passenger side and it didn't. Any of you all had this issue? Is it normal? It sounds bad. I am mechanically inclined, I do all my own work but this didnt happen on my 2001 Sierra. I was tired of working on that all the time so I just bought this as my replacement and I'd hate to get into it already. Thanks in advance

dtnel78 · April 24, 2020

Curious as if this is a 1500 or 2500? Buying a 2500 would make it more likely that a vehicle was used for towing or as a work vehicle when compared to a 1500.

One thing that'll tell you for sure if it's a wheel bearing or not is when you go around a curve if the noise gets worse.

I replaced both of the axles on the front with Timken within 8-10yrs if I had to guess.

Did the 2nd one 120 miles from home with 2 - 1/2 cows in the back on a hot summer day in a bank parking lot next door to the parts facility. Luckily it's the same regional parts company I use here at home so I still get the lifetime warranty.

Maybe try disconnecting both axle shafts and rotate the diff manually by hand and see if you get the noise still.

Sometimes you'll get noises from one side to the other.

Check the U-joint shafts from the transfer case to the front diff as i've seen u-joints cause clicking, vibrating, etc.

You said you bought this used? How long ago?

A good rule of thumb is if you get a used vehicle and you don't know the history or can't get service info (very easily obtainable thru any dealer as long as they've worked on it), (also warranty information repairs are easily obtained).

I always on used vehicles have a transmission shop I use go thru and service the transmission, transfer case & diff's unless I have time then I'll do the diff's. The main reason for doing these is someone else's problem may have been sold to you so also when shopping for vehicles look for new fluid and even if you want a good peace of mind take it to a reputable shop and pay them the $70-$120 for a good vehicle inspection as the stuff they find will give you bargaining power when you go back to the dealer.

A good shop can hook the computer up and run it down the road, check sensors, inactive (soft codes), transmission data as long as the tech knows what they're doing.

I inspected a Subaru recently and saved the guy over $1k. Though 2 months later he's having a misfire (spark plug oil tube seals leaking that'll cause that). It wasn't evident when we'd inspected it as shops will clean rather than fix things right when prepping a vehicle for sale.

Some dealers and shops when they find signs of issues will drain and full the fluid then ala the metal shavings we're gone.

My suggestion is get a oil drain pan and pull the drain plug in the front diff. If it comes out dark let it drain completely and watch for any metal particles. If you've got shavings and need to put a diff rebuild kit in it just make sure any specialized tools you'll need you have or can maybe rent at auto zone or a place that has a tool loaner program.

Sometimes a transmission shop may have rebuilt ones on the shelf and you can swap out if yours is bad and you just give them you're core (this way will cost a little more as someone, local or elsewhere rebuilds them.

Definitely check the u-joint cups first as they rust and you can't see it till they're apart.

Just had a u-joint go out I replaced 5yrs ago and it was vibrating for about 6-8 months in certain speed ranges. Didn't bother at first then it was winter so waited it out and kept a jack, jackstand, u-joint, tools on hand in case it went out away from home. I got lucky. I also had to do intake gaskets and an O2 sensor during this time.

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JLS81 · April 25, 2020

Thanks man. I appreciate the reply. It's a 1500. I was hoping it was a wheel bearing as I've done them and this truck will be easier as it's almost rust free. That said the usual symptoms aren't there for a wheel bearing. I'll try disconnecting the axle shafts, that's a good idea. And I got a transmission shop here in town that my dad has gone to. He trusts them so I'll probably have them take a look. I've had the truck for about a month and put two thousand miles on it since then. Kind of disappointed to have any trouble already, but hopefully not a big deal. Any chance that 4wd is partially engaged? Does z71 give you a front locker that could be slipping? I guess I won't know until I get in there. Thanks again

Jackson

JLS81 · April 25, 2020

Update: I pulled the fill plug and the drain plug out of the front diff. To my surprise, not a dribble or drop. There was plenty of muck on the drain plug, with a few metal shavings probably 1/8 inch long and real thin. The top fill plug was dry. I figure that's not good. A t all. My thinking is that the drivers side seal went bad, letting the fluid out, and that killed that output bearing, causing the noise. Anyone else have a better idea, or dealt with this before?

davester · April 25, 2020

It should be VERY obvious where the oil went. My front diff had seals that just weeped a small amount of oil, and the axles sprayed the oil quite nicely, without the oil level going down very much over about 5000 miles (I check every oil change). Unless you never check it, one or both sides should just be covered in oil.

Get the front wheels off the ground and rotate the wheels by hand, perhaps with a mechanics stethoscope to listen to the diff where the stub axles go into it and see.

I'm just familiar with the earlier diffs (but I think yours is similar), where the passenger side is straightforward and relatively easy to do (and you can do it just taking out the passenger side of the diff, not the whole thing), while the driver's side requires the diff to be removed, and it's easy to do only if you get lucky and can pound out the stub axle. You have to hammer the axle outwards, and hope the retaining clip hops out of it's groove. If you can't hammer it out, you have to torch off the end, then disassemble the diff to get the remaining part out.

If you've been using 4wd a bunch with it out of fluid, you might consider just getting another diff from a junkyard or someone parting out their truck (with the right gear ratio), and swap it in. Easier, faster, and less worry about other bits inside the diff being damaged from running without oil.

JLS81 · April 25, 2020

I filled the diff with sae 80w90 gear oil today and rolled around in 4 to get it worked through good. At first I got a little noise but that went away after a few seconds. Back in 2H, I jacked it up and spun the wheel just like I had before. Real smooth, no clacking and clunking like before. That was a welcome surprise. I'm going to change the fluid in the rear diff and transfer case, and check them every oil change like I did on my old truck. Until then, I will likely be on the hunt for a used diff (3.42 gears of I'm not mistaken..... I'll have to check again) as I plan to keep this truck on the road for another 10 years at least. Or at least that's the plan. Thanks fellas for the advice.