I just picked up a 1999 discovery 2 in kinversand - 44k miles. FL car, stored indoors.

The car did great on my drive to CT from FL except for one issue.

When the car gets up to about 80mph or 3000 RPM on the tach. I get a humming noise when the car is under load. So if the car is accelerating or "braking" under cruise I get the humming noise.

I tried this again last night by putting the car into second gear and bringing the car up to 3000 RPM - and i get the humming again when under load.

I don't hear this nose any other time, than when i have the engine up at 3000 RPM. I am not sure if this is a propshaft issue or something simpler.

Any advice or checks you can suggest would be greatly appreciated.

 

Would check out shaft
Kind of sounds like bearing noise.
You could test half of the driveline at time by removing a driveshaft and locking your center differential. You wouldn't be able to see if you are getting it in front wheel drive or rear wheel drive or both

 

How do i lock the center differential? I see references to this - but dont see a way to do it in the truck?

 

Search the forum for "CDL"...You will learn what it's about.

 

3k? Am I the only one that won't push my Discovery past 2100 or so RPM? Mine is in good working order but I would be terrified to run at 3K.

 

The RPM of the drive shaft in 2nd gear at 3000 RPM is a lot slower than when it is in Drive.
Sounds like something attached to the engine alternator, power steering pump?

 

It's actually good for it once in a while. Cleans out carbon deposits and the like. I've been driving the last 20k pedal to the floor from almost every stop light to no ill effects. Of course, that's very excessive just to keep it clean, but I really like to listen to it roar and I've got a bit of a lead foot. Still, it hasn't caused me any problems.

 

Does it have the same hum if you're in neutral and hold a steady 3k rpm?