My son's explorer, 4.0 automatic, developed a problem during a 90 mile trip on the freeway. Driving along at 75 MPH with the cruise set everything seems fine. As soon as he lets of the accelorator the engine drops to idle speed and a noise comes from under the truck that sounds like an old siren, starts low pitch and gets higher and higher. The noise stops when he touches the accelerator applying power to the drive train.

The transmission shifts and pulls fine, no slippage. He said that for a while the 4WD light on the dash has been flashing six flashes, pause, six flashes.....a steady code.

Any questions or ideas?
Thanks

 

not sounding good
first crawl under truck and check fluid in the t-case if full pull the rear sensor out (back of t-case) clean it and unhook battery this should fix your code....
second fin a steeeeep hill mountian )on black top road go about 60 mph let off the acellerator as the motor is
"braking the truck"pull it out of overdive into 3rd if the truck makes a grinding racheating noise I will be sorry to say your t-case is going south...I can fill you in more just get back in touch
ps ther is 5 diffent t-case for a 97 explorer

 

Can you please elaborate more on this problem. Think we have the same thing on a 98 4.0L 4WD Explorer. Shop says that we need a new transfer case after they rebuilt the transmission and I was calling BS on it but now I am having second thoughts after reding this. There are not that many parts in the transfer case. What in there could be making this noise.

 

If this happens when the truck is stationary it cannot be the transfer case..

If it changes pitch(speed) that would also eliminate the transfer case as the case is direct drive to the back wheels and so only turns as fast/slow as back wheels allow..... Philip

 

I think I found the issue. Looks like it is in fact the transfer case. I would not have thought so but.... See link below.

https://www.ford-trucks.com/forums/1...ing-sound.html

 

I also ran into the same thing... a loud knock coming from under the car (which I originally thought was the tranny), then reverse slipped one day and the problem seemed to be gone. The exact "grinding/slipping" noise returned with a venegance and I needed a tow home.

Note: my truck wouldn't move in N or D or 4X4 High, but it didn't have a problem at all in 4X4 Low. After sitting overnight it started up and moved fine.

I don't doubt I have the same defect in my Transfer Case as explained in this thread, but I seem to have fixed the issue (for now) with draining and refilling the case with a Lucas Tranny additive and topping off to the bottom of the fill hole with ATF. Dunno what it did to the internal workings of the Transfer Case but all noises are gone and the car downshifts fine. I have especially tried driving in the the 40 - 60 MPH range which is where the issue seems to have been acting up the most.

Any thoughts?