***SOLVED******
99 Ford 2WD Expedition Eddie Bauer Edition 5.4 Liter 4R100 transmission with factory tow package 165,000 miles I have two vehicles so it's not driven too much
I've had my 99 Ford Expedition since 2002. I take extremely good care of it and have always changed fluids, including draining the Torque Converter when maintaining the tranny. About two years ago, the mileage started to drop. I checked/changed the O2 sensors, and the power got a little better, but the mileage continued to drop. Now it is making a whining after about a 3 minute warm up. It sounds like it has steam whistle underneath it and it also whines while decelerating. The whine gets noticeable around 1200 rpm's and then gets worse as it gets higher. The sound changes with the shift patterns. There is no shudder, no shift "misses". It feels solid, it just sounds like a turbine engine. The fluid level is perfect. Could it be the torque converter? If so, what TC does everyone recommend. I do some towing, but mostly driving to the mountains so up down highways and I want the most durable/best, not the cheapest. Thanks in advance!

 

If it will whine while at idle sitting still you may want to get you a cheap Harbor Freight stethoscope thingy to help pin point the noise. It could be an idler pulley, alternator, or pwr steering. If you turn on the ac does it change it much (loading up the pulley system)?

 

Between the whistling and power loss you might be looking at a leaking intake gasket or a cracked intake.

 

It doesn't whine when idling....always when the rpms are around 1200-1500 and above. I'll check with the AC on.

As for the power...the engine runs really strong....it just seems like it isn't getting to the wheels....that's why I'm thinking its the torque converter. There aren't any vacuum leaks either...I've sprayed starting fluid around and no increase in idle.

 

Hello...I checked...no change with the AC compressor on.

 

When it is warmed up completely and you have just driven it with the whine present:

1. Find a safe place to park
2. Put transmission in "Park"
3. Carefully rev engine to 1,500RPM

Is the whine there?

 

Thank you...I did this and nothing. It only does it when driving.

 

So the sound ONLY whined while the vehicle was in motion/driving and the RPMs were above 1200 rpm....worst around 1500.

I purchased a STEELMAN Chassis Ear....I now HIGHLY recommend this. I put five of the microphones around the vehicle....the first two microphones I put on either side of the bell housing because I was sure it was the Torque Converter. NOPE

I put three in the engine compartment...one on the Power Steering Pump, One on the alternator and one on the tensioner pulley.

The winner was the tensioner pulley....so loud I had to take the headphones off...I switched around the the TC, Alternator and PS Pump were all super quiet compared....this tool was a LIFE SAVER...I wasn't worried about rebuilding the trans, I was worried if Id have enough room to jack my Expy up high enough because my garage ceiling is low.

Thanks to everyone who replied and offered a suggestion I really appreciate it.