OK Guys I need help,
I have a 1999 Navigator ( AWD) . It has a whining sound when the truck is in " Park or " Neutral " as soon as you put the truck in gear ( Reverse or forward ) the noise goes away. The noise increases with engine RPM's. The whining sounds like it is coming from underneath the truck. Please HELP ME!!!!!

 

Have you checked the fuild in the trans? Or in the power steering pump?

 

I did check the power steering pump, but did not check the trans. mission fluid. I will do this A.S.A.P. Thanks For Your Response!!!!

 

When you check the fluid, it should be a red color. And smell it. If it sells burnt, and or is a brown color you need to service your trans, and it could already be too late.

 

I checked the transmission fluid and it looked and smelled fine. Any more thoughts? Power steering pump sounded good. After i drove the truck about 10 miles the noise stopped., but it will come back when truck is first started. ????????????????

 

have you check your belt, belt tensioner, my expedition used to make a squiky noise.

 

Checked the belt tensioer yesterday, it was fine. Today i may try to run it without the belt to eliminate the belt.