I have a 04 Explorer sport 4.0L with 4WD/AWD. I have had a small pinion seal leak for a little while now. I started getting a groaning noise and small vibration in the front that has progressively gotten worse. The noise sounds like it is coming from the front drivers side. It starts at about 25-30 MPH and gets louder with speed.

1 - I first rotated the tires. They had some cupping, but not the worst I have seen. The noise did not move or change. Tire rotation did nothing for the problem.

2 - After researching a bit, I replace the driver's side wheel bearing. Both sides felt tight, but I replaced the driver's side because it felt just a bit gritty. Again nothing changed. The noise is still the same place and intensity.

Now, I am beginning to think it is an issue with the Differential. The fluid level had gotten low because of the leak. I have since refilled it. Although I don't know exactly how much fluid it took, it seemed like quite a bit. The pinion feels tight with no slop. What else should I check? A used Diff locally will cost me around $350. Any advise on what else to look for, or replacing the diff is appreciated.

Thanks, Charley

 

I had 1 front and 1 rear hub/bearing go out on the 2002 Exp. Its hard to get the location unless the noise is really bad and bearing is shot. I would double check the other 3 by rasing the wheel, pulling tire and blake disc off then rotating the hub by hand and feeling for drag, sticking, noise. If you dont find much, then i think you right, its inside the axle. probably the bearings on the end of the bevel gear became galled with lack of oil level. Now they got a bad spot on one ball in the bearing.

 

Well, it was the passenger side wheel bearing causing all the problems. I change it and everything is back to normal. best part is it came with a new ABS sensor, so I used the old one on the driver;s side so I didn't have to buy a new one. Now I have to address the pinion seal leak. thank you for your assistance.