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Q: 4WD transfer case issue

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Okay my wife drove our trailblazer 45mph in 4 low so a bunch of grinding had accured. So I took it out and used awd worked fine. Then it rained so I took it out again. I had to cross a few washes that had ran a couple nights before so they were dry. But had to use 4 low. It worked fine until I started back home. Then I herd like a grinding sound at first then it stopped. Then it started getting real hard like something was stopping my car. Then the grinding started real bad. Sounds coming from front. So I stopped using it. I came home put it back in 4 low and everything engages except I can here like a shaft or something just spinning. So now no 4wd. What's the issue and what parts do I need.

My car has 175000 miles.
My car has an automatic transmission.

A: Hi there. It seems like what happened was, ...

Hi there. It seems like what happened was, when putting the vehicle in 4WD low and driving at a high speed on pavement this could have caused the front axle to burn up. This is because the front differential has a lower gear set than the rear differential. If you have ever wondered why you vehicle tends to be a little jumpy when putting it in low then that is because the front axle wants to turn faster than the rear axle. Since you hear a shaft turning but not the front wheels, then the front differential has destroyed itself.

To verify this, jack the vehicle up to where all 4 wheels are off the ground and on jack stands. Start the engine and put the transfer case in 4WD low and put the transmission in Low. Now, let off the brake and have someone look at the wheels. If the front wheels are not turning and you hear a whining noise, then the differential is destroyed. You will have to remove the axle cover and drain the oil for an inspection. If chunks of metal or lots of metal is on the magnet, then the differential has been destroyed and needs replaced. If you need further assistance with your vehicle, then seek out a professional, such as one from YourMechanic, to help you with the 4WD low issue.

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