I have a 2002 Explorer that has 165,000 miles on it. Wehad the transmission replaced by Aamco 2 years ago. Ever since the transmission was replaced there hadsbeen a noise in the right rear like you are running over speed strips when the speedometer hits 35, 45 and sometimes 55. Took it back to Aamco and they said that it was out of warranty (over 10,000 miles) and that they thought it was the torque convertor. THat was over a year ago and 20,000 miles. It still does it - we have changed the tires so it is not that. IT runs great but that vibration/noise makes me nuts. Everyone that looks at it has a different opinion but no one seems to know what it is. Has anyone else ever had this happen? (It was hit in rear end when I first got it - but never had any issues after it was repaired at a Ford dealer)

 

Does the noise change when you let off the throttle? How about if you carefully shift to neutral? If it still makes the noise when shifted to neutral it is probably not the torque converter and more likely to be a u-joint or issue with the rear differential or pinion. Has anyone drained the rear differential, inspected the gear oil, and installed the problem amount of the proper gear oil back in the differential? Also try gently applying the brakes when the noise starts and see if that has an effect. Does the parking brake hold?

Also, does your Explorer have Control Trac, 2WD, or AWD? Does the noise seem to only be when the truck is under load (such as accelerating or going up a hill)? Has the transfer case oil been drained and refilled?

I would start with the rear differential fluid and see if that make any difference with the noise. If no difference, then change the fluid in the transfer case and see if that makes a difference. You could also mark how the driveshaft is installed, then remove it and inspect the u-joints for stiffness or play.

-Rod

 

Thank you for the info - it only does it when it is under load (accelerating) if you et off the gas it stops or if you accelerate very quickly it doesn't do it. I will try what you recommend and hope that it quits from there. The transfer case is a different issue. Sometimes if it is raining and the tires spin up water or if you go through a big puddle it will jump into 4 wheel by itself. I really would like to keep it because no payments so I am trying to get everything fixed.

 

The noise being prevalent only under load sounds consistent with what many accept as pinion noise, and it will likely change with the correct gear oil and additive. However, the pinion noise I've experienced is no where near as loud as rumble strips like you suggest in your first post. Well, I guess I'm not familiar with "speed strips" and visualize them as being the rumble strips that are in highways shortly before stop signs.

The transfer case shifting when wet is likely to be an issue with the transfer case shift motor assembly. There are several threads already on this subject so I won't turn this thread in to another one. You can try the "Search this forum" feature to read up on that motor.

-Rod

 

As shorod mentioned, this noise happening only during an accelerating load usually means a ring/pinion gear problem. These differentials are notorious for this problem. My 2002 Explorer has 235,000 miles and the differential has been rebuilt twice for this same issue. Replacing the oil may help you but I wasn't so lucky.

If you do decide to change the differential oil, check the service bulletins. I believe that as a result of these problems, Ford replaced the recommended viscosity to 75W140. Also, if the differential is limited slip, don't forget to add the friction modifier.

Also prevalent on these trucks is failing wheel bearings, which also give off a noise which sounds like driving over rumble strips, so that could also be the culprit.

The way I determine if it's the wheel bearing is as follows: (Warning - I can not officially recommend this procedure due to safety concerns and liability issues). I jack the entire rear of the truck until the tires are well off the ground (mine has limited slip so both sides will turn), then put jack stands under the frame and chock the front tires. I have someone start the truck and very slowly accelerate it to highway speed. I use an automotive stethoscope and place the probe on the wheel hub housing which holds the wheel bearing (the part that the CV axle goes through on the outboard end). A bad bearing will sound like a loud roar through the scope. A good bearing will sound smooth.

Using the stethoscope also helps diagnose problems with differentials and engine components as well.

Hope this helps.

 

It takes a little longer but i try to narrow it down to front or rear by sound. Then i jack kup the truck and remove the tires and brake disc. You can rotate the hub by hand without the brake dragging noise and usually tell which one it is. sometimes you can feel and hear the noisey hub..... I also have the gear noise in my 2002. I was using 75 w 140 and had some noise. I put in 80-90 during a service and the noise got worse. THinking that heavier oil might dampen out the noise, i bought two quarts for EP 320 gear lube and installed that last week. So far i like the improvement. Will see in a month or so if im still impressed. If you have a LS unit, i might not try the heavy oil, but for a standard axle, it should not effect anything, but give a thicker oil film on the gears.

 

steve whatever happened on using the EP320 gear lube on your Explorer

 

The heavy oil appeared to help at first. Within several months I decided to look inside at the bearings and gears. Ended up changing out all the bearings and reusing the gears. My opinion was the pinion had been "TIGHT" setup from the factory and was possibly the noise problem for several years. It did have several thousands wear. Also carrier bearings were showing heat marks from too TIGHT... 90% of noise gone after new bearings, but keeping old gears.

 

rear end rebuild of IRS unit.

https://www.ford-trucks.com/forums/1...e-rebuild.html

 

Thank you sir.

I drained the rearend diff. and refilled 75/145. The noise has been reduced about 20%. My plans are to replace the gasket as I noticed a leak and I was thinking about using the 320.
As far as a rebuild is concerned that will be december 2017.

-Alan

 

I would think twice about replacing the "gasket"... If your talking about taking off the rear cover, it is actually the mount to the frame. .. might not be a good job.... Every time I have changed oil, it seems like the noise drops slightly for a couple weeks.. I think just being "NEW" helps.

 

Crap. I need the leak stopped. Guess I will have to take it to a mechanic.

 

If it leaks bad, you might be able to clean and rub JB weld or something over the joint in that area....... To "FIX" the face leak, you will need to pull the pumpkin and set on the bench I think.. very difficult to replace it on the truck.. to get the pumpkin out, your removing the driveshaft and both axle half shafts.... might as well check bearings if its setting on the bench.. Depends on how bad it leaks on what to do next.

are you sure its the back face, and not the pinion seal in the front that is leaking ?? Clean and look.