Today my 04' Explorer made a loud clunking noise from right rear. Now it wants to surge forward when at idle, in drive and my foot on brake.

What happened?

 

I don't see how anything at the rear of the vehicle could make it drive forward at idle... The motor drives thru the transmission and torque converter to the wheels.. You have to get the torque converter to lockup to push hard at idle. I would guess more of a torque converter area problem... Is there an OVER DRIVE button on the end of the shift lever ? Push it and turn off and see if that makes a difference.

 

Turned out to be differential issue. Right rear axle loose in diff housing.

Looks like a new (junk yard) differential

 

Replaced rear differential & right rear axle. Car runs & drives OK now. Gears a bit chewed up.

Curious as to what may have caused this. Car has 160k on Odometer.

 

gears normally don't fail on their own... bearings fail, then take out the gears... how would this make the truck try to MOVE when setting at idle with the brake on ?

 

Don't know but that was the symptom. In drive with foot on brake, at idle it would surge. Now it doesn't

Both rear wheel bearings are OK.

Only thing I see is left rear sway bar is bad & needs replacement.

 

Maybe the speedometer sensor in the differential was thrown off and caused a surge in the motor? Only thing I can think of.