What could be making this noise???

[jlppimb]

The Specs: 1997 4X4 Explorer XLT 4.0 V6(no SOHC) 185,000 miles

Last night driving to and from work I noticed a strange revving sound. Sounds like its from in the engine compartment. Had the cruise control set @ 70 mph. Sounds like something would rev up and then and rev back down, and kept repeating. Tach never changed and neither did the speed. Steering wheel didnt vibrate any worse than normal but it felt like the floor board did maybe a little. Talk to a local repair shop that I deal with and was told it maybe sounds like it could be the torque converter. The shop didnt take it for a test drive, just went off what I told them. Does not repeat these symtoms at lower city speeds, seems to only be highway speed. Any help or ideas would be appreciated.

Thanks,

Todd

 

[ExploringNC]

As the transfer case starts to go it will make a sort of reving sound when you let off the gas and coast.

 

[jlppimb]

The "revving" noise does not happen when I let off the gas and coast. So far I have only been able to get the nose to appear at highway speeds around 60 and up.