Possible bearing noise in front end

[xbljackalblood]

Car in question: 98 5.0 AWD with 3.73LS and 150k.

Noise sounds like a bearing issue in the front end. Occurs mostly at low speeds (0-20mph); both accelerating (winding up noise) and decelerating (winding down noise). Does not occur in neutral/park.

Occurs sometimes after a shift in the trans; basically low whine to high whine, shift, low whine to high whine, shift, etc.

Noise mostly/completely goes away when maintaining a constant speed. Disappears completely when all four wheels are off the ground and spinning at all speeds.

Fluids in the trans, transfer case, and rear diff were changed with fully synthetic Amsoil less than 100 miles ago. Front diff is full, haven't had time to change. Noise did not change.

Transfer case is not binding as all four wheels spin when off the ground.

Both front wheel bearings are smooth with no play. Suspension is also tight with no play.

Tires were replaced with 265/70/16 General Grabber At2s and the truck was aligned to spec. Noise did not change.

The tires and fluids were changed for maintenance reasons only, not to fix the noise. Again, there is no noise at all when up on a lift so this has me stumped. Any questions, just ask. I have access to a lift if that helps with any tests or ideas you guys might have. Thanks.

 

[jremington59]

Pull the front drive shaft and take it for a short ride. If the sounds gone you've narrowed it down to an AWD issue.

 

[xbljackalblood]

Alright, I'll try dropping the front drive shaft tomorrow. Thanks.

 

[xbljackalblood]

Okay, I removed the front drive shaft and the noise disappeared. Truck is also much easier to steer at low speed. Could the VC be locked up? Possibly a bad CV joint in the front shaft? Or am I looking for a new TC?

 

[jremington59]

How does the front shaft look? Is the sound a growl or could it be a loud vibration?

Without a load on the shaft it's going to be hard to find play. I don't think it's going to be in the diff as that's still turning with the shaft out. When you put it back in grab it and see if there's any shuck in it. If it's original it's reaching it's wear out date.

 

[xbljackalblood]

Sounds more like a growl than a vibration. The CV joint seems like it doesn't have very much grease in it, and I can hear the balls in the joint very lightly clicking when rotated. I assume that light clicking would quiet down with a good amount of grease, otherwise looks to be in good condition. Also, what do you mean by "shuck?" It doesn't have any play side to side, just in and out when out of the car. When it's in the car, neither the u-joint nor the CV have any play whatsoever.

 

[RomeovilleIL]

Play would indicate worn bearings, but just as often they are pitted with rust so the joint binds. The dome cap is press fit against a reusable o-ring type seal. It can be easily popped off with a little prying through the bolt holes. The cv joint should flex smoothly with no discernable rough spots (don't go more than about 30 degrees or you may slip a bearing out - they are not easy to put back in!). You can rotate the joint in hand, or place the CV in a vice and swing the shaft in a full circle.

So long as the boot is intact, add a couple tablespoons of grease and work into the bearings by turning the joint. It should be pretty evident if it works or not.

The dome cap will press back in place as you tighten the bolts to reinstall in the truck.

 

[Lizard]

Sounds more like a growl than a vibration. The CV joint seems like it doesn't have very much grease in it, and I can hear the balls in the joint very lightly clicking when rotated. I assume that light clicking would quiet down with a good amount of grease, otherwise looks to be in good condition. Also, what do you mean by "shuck?" It doesn't have any play side to side, just in and out when out of the car. When it's in the car, neither the u-joint nor the CV have any play whatsoever.

How did this saga end? Was it the front drive shaft? I'm chasing a very similar sounding problem. Thanks.