Roaring noise when auto 4x4 engages

[BrianDye]

I dont know the best term to describe this issue, so I couldnt find much when searching around.

I have an XLT with the 4x4 Auto, 4x4 High, 4x4 Low on the dash.

When the roads are slick from rain/snow and the rears slip and the auto engages, it works great and does its job, but I get this "roaring" type noise I can hear and feel through the floorboards, steering wheel, etc.

Im not sure exactly how the system works, like if it engages and stays engaged for a period of time even after theres no wheel spin? Because this noise will stay for quite a while after the 4x4 had to kick in. It gets worse with higher RPMs.

When I put it in 4x4 high, theres no noise really. We had some nasty snow drop on us very quickly about a week ago, roads were terrible and so was traffic, so I put it in 4x4 high just to take off from the light to merge onto the highway and turned it back to auto, no noise, 4x4 worked flawlessly. It seems as if the noise only happens when it automatically engages.

In 4 low, if I turn the wheel and drive, there is a pretty nasty noise which makes me think the cv axles could be going bad?

Im going to check and change the front diff fluid this Sunday with a pump to just pump the old out and new in. Could low or old fluid cause this? I would think 4x4 would either not work, or it would make awful/loud noises when engaged.

 

[Trac Marks]

Is this truck new to you? Is this your first winter with it?

Roaring doesn't sound right, but mine definitely makes noise to let you know everything is working. You have the Advance Trac, RSC (roll stability control), ESC (electronic stability control), engine throttle input control and brake distribution hard at work, so wheels that are slipping are getting brakes applied, torque is being redistributed, throttle input reduced, etc. You will certainly feel this in the brake pedal and somewhat in the steering wheel.

Try this. The Advance Trac button to the left of your 4x4 AUTO button.... press and hold the Advance Trac button for like 5-7 seconds. After the first 2 or so seconds the Advance Trac light will blink maybe twice, but after the 5-7 seconds, it should blink several times then glow solid.... In 4X4 AUTO, now see if you can break traction and determine whether or not the noises follow.

4X4 AUTO will distribute power/toque as needed using the above mentioned systems.
4X4 HIGH (and LOW for the matter) will lock front & rear wheels together.

In 4X4 HIGH (or LOW), yes, turning the wheels makes you think something is going to come apart. Thats normal.

Hope this helps somewhat.

 

[BrianDye]

The truck is fairly new to me, a few months now. I had a 95 a few years back that also had the "same" options, auto 4x4, high and low. I'm sure the system is a bit different, but it was basically AWD in my book. Any slipping and the front tires kicked right in, silently and smoothly.

I would hope this is not normal, and I feel like the average owner would be taking these to the shop anytime their AWD kicked in lol.

I do need an alignment, mine slightly pulls to the right, but I didn't want to waste money on once since I plan on a front end overhaul (tie rod ends, ball joints, etc) and new tires/wheels next season.

I will see if I can find some slick spots later and try the test you suggested and post the results back, thanks for the idea.

 

[BrianDye]

I held the button for about 6-7 seconds until the light flashed, and then in some dirt got the wheels to spin. Was a small area and I was waiting for my passenger to come out of the store so I couldn't drive right away, but the noise still happened and continued until I was on the highway it stopped about 1/2 mile after I hit 70.