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2005 Silverado 4WD issue

2005 Chevy Silverado LS 5.3FF AT w/ manual 4WD: shifting into 4WD is smooth, but transfer case seems to whine and when you shift back to 2WD it shifts smooth but seems like the transfer case doesn’t disengage right away. When it does there is a clunk/bump. Thoughts?

Also, I don’t use 4WD much, just in the winter when the roads are slick and the 400lbs of sand in the back of the truck don’t cut the mustard, and at that just to take off from a stop or to pull someone out of the snow bank. Thanks.

The clunk/bump is the truck unlocking the front hubs so the axle doesn’t turn in 2WD mode. The button on the dash disengages the transfer case right away but the hubs won’t unlock until load is released. That takes a little easy driving to accomplish. I have a similar Chevy, it has never been silent. Always a slight clunk when the hubs release.

The whine may be the chain inside the transfer case making noise or it may be the front differential gears being noisy. Have you checked the oil level in either the transfer case or the front diff? You should,

Mine, an 03 trailblazer just started clunking this year when doing 4lo, auto no noise when 4wd kicks in, I exercise it regularly, have a small pinion seal leak, waiting to check for low fluid till it gets to be a tolerable temp.

NShifting in and out of 4wd will elicit noise from the actuator and the drive train in general. To minimize the noise, don’t initiate the shift when the drive train is under load either by accelerating, engine breaking or turning a corner. But, as they age, it is also normal to get a little noisier when making the change. Remember, it’s like a gear change in an outboard motor on a boat with no clutch, so expect eventual noise.

Worn front CV joints could be a problem too.

Secondly, your drive train needs to be lubricated regularly and the front diff and associated parts need to be used once a month at least for about 20! Minutes. More problems with truck based 4wd are caused by incorrect use and lack of use then over use. These systems are really tough and last a long time with few problems if used regularly and correctly.

NNWhether it has hubs that go in or out can be checked by rotating the front wheels when in 2wd and observing the half shafts. I can only tell you that Toyota has not had locking hubs for years and rotate shafts to the front diff continually. THe 4wd in many trucks is engaged and disengaged by a differential actuator in the diff and another at the transfer case.

So, worn CV joints up front could be a problem too.
Many HD ttrucks still have manual hubs…

GM uses electric actuators to lock and unlock hubs, at least in that era Silverado with the push-button, 4WD 246 transfer case.

The Toyota 4WD with a similar problem was another thread. It surprises me that Toyota has no way of disengaging the front axles. 2 schools of thought, maybe. 1) Turn them so they don’t bind up from dis-use or 2) Disengage them to reduce driveline drag - better MPG’s.