High speed whine

[Soliyou]

Hi everybody,

I started hearing a faint whine that starts at 70mph under any throttle application.
Goes away under no throttle.

I have the fx4 package but it happens in 2wd or 4A.

Anybody experiencing the same issue??

Diagnosing this at the dealer will be almost impossible since it happens only at highway speeds after about 30 minutes of driving.

 

[Dice Roll]

Not heard that on mine. How many miles do you have? Off top of my head that sounds like a rear gear issue.

see if you can set it up so you can stop at a set time and pick a tech or service writer up so you can get it fully warmed up. It can take about 30 minutes to fully heat up fluids and that’s when a clearance issue will crop up.

 

[Soliyou]

It only has 17,000 miles.

Should I go ahead and check the fluid level in the rear diff?

 

[Dice Roll]

You could. Would be easy in the days of covid to avoid people, but I doubt it’d be low enough to cause the issue now. Who knows, anything can happen. Any leaks?

my f350 has the rear gear set up wrong. Never heard it over the diesel. Had about 220,000 on it when I changed to a higher gear and learned that...

 

[AndyMA]

I noticed the same whine @ 70mph+. Gets louder as speed increases to 80+. Only when on the “go” pedal, and quiets when off the accelerator. I have 2020 XLT FX4 with max tow pkg and 2K miles.

 

[aggiegrad05]

https://www.expeditionforum.com/threads/2018-expedition-max-whining-noise.41357/

 

[Soliyou]

https://www.expeditionforum.com/threads/2018-expedition-max-whining-noise.41357/

I followed this thread, but this whine doesn’t occur while coasting or in neutral. Only When throttle is pressed.

It sounds more like a slipping clutch.

 

[Soliyou]

Time for an update:

Over the past couple of months I did the following:
- checked transfer case fluid. Fluid was ok but I went ahead and changed it.

- checked rear diff fluid. Same, fluid in good condition but changed it to inspect lower Drain plug magnet. Nothing out of ordinary.

- checked front diff fluid and it was ok too. But i couldn’t take more nasty fluid smell so I left it alone.

After all this, whine is still here. Only under throttle above 75 mph. But as time goes by, it is getting a bit louder.

Will wait until it is clearly audible and take it in.