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Grinding noise from front end

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by Cobrasix, Aug 14, 2012.

  1. Cobrasix

    Cobrasix New Member

    Okay, truck an 04, 1500 Z71 ext. cab and has 320k miles. Original front end. Today, almost all the way to work (20 miles) started to get a faint grinding from the front end. When I got to work, looked for obvious stuff stuck to the axle, but nothing. Going home, it was quiet at first, but after 20 miles, same noise. The noise is almost like that of the 4wd being engaged on dry pavement. When I turn to the left, it does get a little quieter. When I turn to the right, a little louder. It's not a clicking noise.

    So tonight, I changed the fluid (just in case) with Mobil 1 75w-90 synthetic. The front differential looked low, but no obvious leaks. the drain plug magnet has some metal filing on it.

    I washed the underside around the axles, wheels, etc, and checked my air pressure in the tires. Noise is still there.

    Noise doesn't change when I apply the brakes.

    Recently, on Friday I had to drive through some high water on roads (12" or so). No problems. Saturday, picked up a few yards of mulch that ended up sitting in the back until Sunday. Truck wasn't driven more then 2 miles with the mulch and haven't had problems in the past with the load (and not sure it's connected at all, but figured I'd include it). 4 weeks ago, I replaced the rotors, pads and calipers on the front end (along with rear rotors and pads).

    Noise doesn't really change if I'm in 4wd or 2WD. There is some play in the forward drive shaft that indicates the U-joint needs to be replaced, but that should even be moving in 2WD.

    so, I'm guessing it's a worn out wheel bearing from the driver side front or possibly the front differential. Any other tests I should try?
     
  2. paracutin

    paracutin Rockstar 100 Posts

    The hub going bad sounds possible although I have never had one go out that didn't squeak or squeal first. Grinding was always the "death noise".
    Do you know how to check for play in the hub?
     
  3. Cobrasix

    Cobrasix New Member

    That's what it was odd to me at first too. I've replaced lots of wheel bearings over the years in various cars, and all of them squealed and I replaced them immediately so never got to grinding. Only thing I can think of is if driving through the high water made it go bad. I had that happen on a volvo once. Hit a large puddle of water (very large, going very fast) and 5 minutes later the bearing assembly was making all sorts of noise.

    I'll check for hub play when I get home tonight.
     
  4. Hidef

    Hidef New Member

    Jack it up as soon as the tire is off the ground you will be able to tell if the hub is bad. Replace both of them if one is gone the other won't be far behind.
     
  5. paracutin

    paracutin Rockstar 100 Posts

    I respectfully disagree. I have never experienced that nor have I seen it recommended. One example; I replaced the left side hub on an old Skylark and drove it another 50k miles without so much as a peep from the right side. Hubs aren't like brake pads. No need to replace them in pairs.
    Also, jacking it up until the tire is off the ground is not usually enough to tell if the hub is bad. If it is, your hub is way beyond bad. You need to grad the tire at the top and bottom and push/pull in and out to check for movement. My left hub has about 1/8" of movement in it. The right has none. You cannot tell by sight alone that the bottom of my left tire, when off the ground, is in 1/8". And, as of right now, the left side is not making any noise.
     
  6. Justice17

    Justice17 New Member

    I gotta side with paracutin on this one, I replaced my left side wheel bearing hub about 10,000 miles ago and not a single issue with the right side....yet. Please someone knock on wood. But on to the hub making noise topic, mine made no noise at all when it started going out. No grinding, nothing, one day I went into a local brake joint and they told me (and showed me) my hub was completely unseated! I never would've known otherwise. It's safe to say I'm a novice but quickly catching on. Also I have heard the noise front diffs make when they go out, and it's more of a howling noise. An easy way to test is accelerate to about 15 mph then ease off the gas so you're still in it but just enough to maintain speed. If it's the front diff you'll hear a very low hollow kinda howling noise. Hope this helps. Good luck!
     
  7. Cobrasix

    Cobrasix New Member

    Well, I got two hubs. Not sure I'll replace both of them, but at least this way I have one on hand. Love Rockauto, but waiting for a week isn't always good when I need the truck in action.

    But I know the howling you are talking about, and it's not that. When I flushed the differential, didn't see an abnormal amount of shavings when I swept a magnet through the fluid. Just hoping it's not the carriage bearing. if so, I'll just replace the whole differential at once. Too many miles (320k) to bother with just replacing parts of something that is easy to replace wholesale and is likely to be cheaper in the long run.
     
  8. Cobrasix

    Cobrasix New Member

    Well, turned out to be the wheel bearing as suspected. 1.5 hours and all good. Would have gone faster except I put the dust shield on backwards the first time and didn't realize it until I was putting the rotor back on. DOH! This is why I usually take pictures as I pull stuff apart.

    But, I cut open the old bearing out of curiosity (used to do failure analysis for my old job). Definitely was the result of water intrusion into the bearing. Looked like the seal was just worn out and waiting for water and debris to sneak in. Fjording a small stream did it in.
     

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