unexplained noise

Have a 97 exploer sport v6. When letting off accelerator I get a loud sound that i only can describe as like a high speed cable wench winding. Sound will stop immediately if i put foot back on accelerator. Sound does not always happen. Sometimes not for days and then sometimes it wont go away for miles when it starts. The transfer case motor is shifting when we tested it. When noise is happening it seems to pull down the tach. Other than this noise vehicle is running perfectly with no jerks, missing or other noises. There are no warning lights on such as the check engine light. The ford mecanics in town can't tell us where to look. Can you help?

Have a 97 exploer sport v6. When letting off accelerator I get a loud sound that i only can describe as like a high speed cable wench winding. Sound will stop immediately if i put foot back on accelerator. Sound does not always happen. Sometimes not for days and then sometimes it wont go away for miles when it starts. The transfer case motor is shifting when we tested it. When noise is happening it seems to pull down the tach. Other than this noise vehicle is running perfectly with no jerks, missing or other noises. There are no warning lights on such as the check engine light. The ford mecanics in town can't tell us where to look. Can you help?
It sounds like the speedo cable is binding. Do you notice the indicator fluctuating when the noise is present? Look for a bind in the cable or if worse comes you'll need to take the dash apart and put some graphite or lithium grease into the cable housing.

Does the 1997 use a speedometer cable, or is that an electronic speedometer like is used in 2000?

Do you ever hear the noise on a cold start or when when you turn on or off the A/C? Maybe the Idle Air Control (IAC) motor is noisy, or maybe you have a driveshaft u-joint that is binding when unloaded.

-Rod

Have a 97 exploer sport v6. When letting off accelerator I get a loud sound that i only can describe as like a high speed cable wench winding. Sound will stop immediately if i put foot back on accelerator. Sound does not always happen. Sometimes not for days and then sometimes it wont go away for miles when it starts. The transfer case motor is shifting when we tested it. When noise is happening it seems to pull down the tach. Other than this noise vehicle is running perfectly with no jerks, missing or other noises. There are no warning lights on such as the check engine light. The ford mecanics in town can't tell us where to look. Can you help?

cruzin4word
I have exactly same problem did you resolve it and how thanks part time mech

Try turning on your A/C with the engine at an idle and see if there is a hint of the same sound. If so, the noise is probably your IAC.

-Rod

shrod thanks for responding
ac no ac no change I thought maybe fan clutch but the sound but the sound decrement with rpm it does change but not incrementally I've been hearing transfer case wheel bearings but because of above statement it doesn't ring thru How about any motors such as transfer shifter motor ??

thanks part time mech

Do you know if your Explorer has a secondary air pump?

When you turned the A/C on, did the engine speed drop and stay there, or was there essentially no drop in idle speed? No drop would indicate the IAC is working properly.

-Rod

I have a simuliar noise but its coming from inside the throttle body or intake cant figure out what it is.

You probably have an Idle Air Control servo that is wearing out. This has been a pretty common complaint.

Try turning your A/C on at idle and see if you hear hear the noise momentarily.

-Rod