Transmission Whining
I have a 1996 Explorer XLT with 185k miles on it. My problem started out as a sound only about three weeks ago – it sounded like a high-speed drill was turning on under my truck while I was driving. The high-pitch sound would increase or decrease with the speed of the truck but not the engine. A quick tap on the gas would make it go away. Only happened above 45 mph.
As it started to happen more often, I noticed it almost always happened when the truck was going down grade or coasting – as when the truck speed was starting to push against the engine and when normal engine breaking would start, the sound would come. When it started to happen almost every time I took my foot off the gas last night, I played around with different speeds and found that I could induce it almost every time the truck started to go faster than the engine once above 35mph. Towards the end of my drive home, every time I was off the gas, or going down a hill: along with the noise showing it’s ugly face, the truck engine was completely detached from the transmission as if I was in neutral and unlike other times I had to come to almost a complete stop before stepping on the gas would result in forward movement.
Other notes: the transmission is shifting nicely during acceleration, and when I provide full throttle it downshifts nicely and the truck speeds up without any odd sounds, vibrations or hesitation. Fluid looks new, smells good and is a bit high on level and there are no signs of leaks under the truck.
I am thinking: torque converter, what do you think?