4wd noise

Discussion in 'GM Powertrain' started by pplus, Feb 5, 2008.

  1. pplus

    pplus New Member

    I have noticed a loud ticking/sputtering noise in my front end, seems to be coming from drivers side, when i am in 2wd and going 80km/h, it goes away when i put it in 4wd, also there is a loud clunking when stopped in neutral and i put it into 4 lo, any ideas what would cause this?
  2. MrShorty

    MrShorty Epic Member 5+ Years 1000 Posts

    Vehicle specs (year, transmission, transfer case, K1500/K2500/K3500, etc) might be helpful information. IFS or solid axle front (GM hasn't used a solid axle front for almost 20 years, but I don't want to assume because there are some of those older ones still out there)?

    If I assume it's a '90+, then the first thing I'd check would be the CV joints on the axleshafts. The only problem with this is I would normally expect the noise to be worse in 4wd rather than better.

    Though it doesn't seem to be common, I would verify that the front diff actuator was fully disengaging in 2H.

    This is normal. Transfer case gears aren't synchronized like transmission gears are. The noise comes from forcing those gears to mesh, even if they aren't perfectly lined up. Sometimes it isn't as bad if you shift from 4H to 4L or back while slightly rolling instead of at a dead stop.
  3. pplus

    pplus New Member

    sorry, it is a 2005 chev 1/2 ton crew cab z71, should i try changing the actuator or is there something i can do to know for sure that is what it is? will be jacking it up this weekend and taking a look underneath
  4. MrShorty

    MrShorty Epic Member 5+ Years 1000 Posts

    I'm rarely an advocate of "guess and check" diagnostics, so I wouldn't replace anything, yet.

    I would advocate exactly what you are planning to do: get under the truck and poke and prod and such to see what you can find. A stethoscope might be useful for pinpointing where the noise is coming from.

    For the actuator, it's purpose is to disconnect the front driveshaft from the axles. So my first thought would be to crawl under and see if you can spin the front driveshaft independent of the wheels. One note: if you have an Autotrac t-case, you may feel some resistance from the t-case clutches, even in 2H. I've seen debates on whether you should be able to spin the front driveshaft at all, but I can on my '98.

    Be sure to be careful if you decide to run the vehicle on jack stands. It can be done safely, just be sure to think through what you are doing. We wouldn't want you to launch your truck through a garage door (or worse).
    Last edited: Feb 5, 2008

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