Droning noise when car is hot

My 1996 Ford Explorer makes this dreadful droning noise - but only when the outside temperature is above 78 degrees and the engine is warm. This is summer 3 and it seems to get louder and louder each year. The doing is loud. I am embarrassed in parking lots. I jab end idea what this is. It does not matter if a/c is on, or the fan. The noise goes away with throttle. Which may mean the engine vacuum is involved in the noise. Help!

The vac line to, or the diaphragm in, the power brake booster?

Should be easy to find. Take an old piece of garden hose and hold one end to your ear. With the car in Park at idle, move the other end of the hose around the engine compartment until you find the source of the noise. Be careful to stay clear of belts, pulleys and fans.

If this only happens at idle with your foot off the accelerator, the noise might be coming from the Idle Air Control valve. http://www.rockauto.com/catalog/moreinfo.php?pk=1005919&cc=1119653

When the noise occurs, open the hood and place your hand on the IAC valve. If the IAC valve is the problem you’ll feel it. Then it’s just a matter of replacing the IAC valve.


Tester - I will try this. Thank you!