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Ron, ASE Certified Technician
Category: Ford
Satisfied Customers: 33055
Experience:  23 years with Ford specializing in drivability and electrical and AC. Ford certs and ASE Certs
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Ford Explorer XLT: We have a new 2003 Ford Explorer 4x4 and

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We have a new 2003 Ford Explorer 4x4 and are noticing problems with it.
1. Upon turning there is a vibration in the rear end. When you walk along with your
hand on the rear tire, right or left there is a chatter, vibration. It happens going forward or back and sometimes going straight from a stop.
2. Driving on the highway and reaching 50-55 MPH there is a really loud wine in the rear end. It almost always quits when you take you foot off the gas but increases going up hill or accelerating. It can be heard at lower speeds but is most prominent at 50 to 55 MPH.

Help!!! We purchased this car for our daughter but are worried! Thanks.

Hello and thank you for your question, My name is XXXXX XXXXX I will assist you today.

The chatter you felling is caused by the posi-traction clutches slipping in the carrier. The type of noise you are describing is in most cases caused by a bad pinion bearing which will make more noise when under load and go quite when you let off the gas and it very likely once you get in there your going to find bad carrier bearing as well. You can usually stop the chatter by changing out the old fluid and adding new fluid along with some friction modifier such as Equa Tork. But its will not take care of the bearing noise your hearing. Unfortunately you are looking at a tear down and bearing replacement. This is a very common problem on the 2003 as well.

If you have more questions and or need more help, please let me know and we can go from there.

Customer: replied 3 years ago.

Hi Ron, I typed a big reply and somehow got shut out of the system so I don't know if you got it. Well here it goes again. What is the carrier you are talking the posi-trac clutches need replaced or just the carrier bearing? Is there a way we can test the pinion bearing to know for sure? If we do nothing and drive the vehicle will it ruin something or make something worse? Is it very expensive to have the rear end worked on or is it something we can do our-self? What fluid does the rear end take 90 weight? When we checked that it gushed out or shot out...could it have been too full? Thank you for all your help on this we really appreciate it.

I did not get it till now and to answer your question, the only way to test the bearing is to remove the carrier assembly from the housing as well as the pinion gear and if your replacing the bearing you should also replace the clutches. It will not hurt anything to keep driving it but the noise will get worse at some point as the bearing wear down further. Unless you have experience overhauling rear differentials then this is not something you want to try and do your self. The type of fluid the rear diff calls for is SAE 75W-140 High Performance Rear Axle Lubricant . You can change the fluid and add about 4 ounces of Equa Tork friction modifier and it may solve the chatter but will not fix the bearing noise. The correct fluid level is right at the bottom of the fill hole so it was likely a bit over full.
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