Stump The Chumps...

[joefnh]

Well after about 2 weeks of searching this forum and talking with 'gijoecam ' I am still confused on what might be causing the increased front end noise and reduced mileage on a 2003 4.0L Explorer 4x4 with 51k on the chassis.

Here is what I know to date:

1.) Increased front end noise (Humm) from 45 -65 MPH (not RPM related). Sounds like an agressive treaded tire. Some increased sensation in the steering wheel as humm peaks in intensity.

3.) Turning the wheel both left and right has the same effect on the noise, some initial decrese for an instant then resumption in noise.

4.) Reduced MPG in the last 3 weeks dropped about 2MPG over a very predictable commute. Some percieved increase in drag, the truck will not coast as easily or as long as before.

5.) Rotated & balanced tires, aligned front end. No change in condition.

6.) Checked brakes for excessive wear, pads have ~ 1/3" remaining. Also tires ok about 17k on them. These tires have been fine unitl recently, wear looks uniform.

7.) And now the clincher, I drove my standard commute today ~ 40 highway miles from Hanscom AFB, and after exiting the highway today I pulled over and decided to check the temperature of the wheel hubs / knucles to see if one wheel was running hot due to possible wheel bearing failure / friction.
What I found is that all 4 brake rotors were HOT enough to burn my fingers (I would guess 250-350F). Is this normal???

I can't say that I have ever checked them after highway driving, But with the ambient temperatre at 60F these seemed quite warm. This would seem a strange design if I wished the brake pads to last more than a month.

Note: I do not ride the brakes at all. Just prior to buring my fingers they were used for about 15 - 20 seconds to slow down on the off ramp.

So in summary is the noise from a wheel bearing or something similar, or from the brakes themselves?

If it is the brakes what could cause them to remain in this partially on state??



Help... Frustrated MIT geek

 

[JDraper]

I'd be looking at the front hub assemblies. Ford uses a sealed bearing unit that cannot be serviced and must be replaced when it goes bad, and they are known to fail. My '01 Explorer needed them at less than 50k miles.

As for the heating. It doesn't take a lot of braking to generate that kind of heat. It's very possible that the brakes are fine. One way to find out if they're dragging and causing a problem is to jack up the front of the vehicle and spin the wheels by hand. There will be some resistance, but they should spin fairly easily.

 

[gijoecam]

I also wouldn't call 2 mpg a significant drop. That can occure simply from the changeover to the reformulated winter fuels.

Brakes are going to get quite warm any time you stop a 5000 lb vehicle from 75 mph. It's how they work. Hot enough to burn is certainly OK.

As I told you in the e-mails, I'd be looking at the bearings/hubs. I may have forgotten to mention, but I had one go bad at 50k, and I've got one going bad now.

-Joe

 

[joefnh]

I also wouldn't call 2 mpg a significant drop. That can occure simply from the changeover to the reformulated winter fuels.

Brakes are going to get quite warm any time you stop a 5000 lb vehicle from 75 mph. It's how they work. Hot enough to burn is certainly OK.

As I told you in the e-mails, I'd be looking at the bearings/hubs. I may have forgotten to mention, but I had one go bad at 50k, and I've got one going bad now.

-Joe

Joe on an 3rd gen how do you replace the wheel bearings? I believe I have read that there is a bearing module or insert of some sort. I am familiar with the type of wheel bearings that are pressed into the knuckle, which of course require removal of the knuckle.

What is involved with replacement of the explorers bearings?

I will probably give it try this saturday if I can round up the knowledge and parts.

Thanks again for all your help

--Joe

BTW New Hampshire does not use the reformulated gas in the winter. Some issue with the additives

 

[gijoecam]

BTW New Hampshire does not use the reformulated gas in the winter. Some issue with the additives

Well, so much for THAT theory, huh? :rolleyes

Bearings are easy.... on a scale of 1-10, 1 being adding washer fluid, 10 being rebuilding a trans, I'd say the bearings are a 4 at worst. The only special tools you'll need are a good set of metric sockets, a good breaker bar, a 32mm socket IIRC.... (I think 1 3/16 was close enough) and that's about it.

NOTE: Before jacking the front wheel off the ground, use a socket with a good sturdy breaker bar to loosen the spindle nut beneath the wheel center cap. I'ts MUCH, MUCH easier than trying to wedge something between the studs once it's all apart. (Experience talking)

Break the spindle nut loose. (No need to completely remove it yet.)
Jack the front end up. Support on properly positioned stands.
Remove the wheel.
Remove the caliper by removing the two bolts that hold the caliper anchor plate to the upright, not just the bolts that hold the caliper to the anchor plate.
Hang the caliper from a piece of wire so it's not hanging by the hose.
Remove the rotor. If the rotor doesn't come off with a few whacks, don't fret. You need to pull the hub that it's attached to anyways, so don't sweat it and skip that for now.
If you haven't already, remove the nut from the CV spindle. (Please note that it's a good idea to replace it if you can. It's a squash-nut and is only designed to be used once. You can get away with re-using them as many people here have, but it's a $2 part to replace.)
Remove the three bolts on the back side of the upright that hold the bearing into the upright.
Pry or tap the bearing out. It should come out fairly easily. (Mine literally fell slipped out)

Oh, and if the rotor was corroded to the hub, you can take it to any good parts shop with a press and have them press the two apart. If they say that they can't get it to budge, tell them to put the pressure on it then whack the hub with a ball-peen hammer and it should pop apart. Sometimes it needs the vibration to crack the rust loose.

Does that help?

-Joe

 

[joefnh]

Thanks to all

Well today per gijoecam's reccomendation I replaced the wheel bearing hub. As promised it was fairly easy. One note afterwards due to te replacement of the speed sensor, the ABS light came on. This eventually went out after ~ 3 minutes of driving.

Thanks again to all the gifted individuals on this site.

--Joe

 

[Glacier991]

gijoecam is certainly a valuable addition to the mindset on this site. Very competent.

 

[gijoecam]

gijoecam is certainly a valuable addition to the mindset on this site. Very competent.

[blushing] aaaw, shucks. Like it says in my sig.... I'm not smart.....

Glad it went back out. I just replied to your PM about the light.... I'm guessing it's all set then? If so, I have no idea why it would have come on to begin with... weird.

-Joe

 

[IAmTodd]

I'd put my money on the hub.

The brakes transfer the energy into heat. So an extreme temperature would be normal. But the wheels shouldn't be excessively hot.