screeching at highway speeds?
 

I'm getting a strange screech sound or squeal that starts at speeds around 60-70 mph and higher, never any slower.

As soon as I let off the throttle the sounds stops.

The sound does not start until I reach at least 60-70 mph, even if I am accelerating at full throttle. The sound is only at highway speeds.

I'm guessing either the IP or turbo may be involved. It is definitely engine related and not driveline.

Could it possibly be a pulley or belt on the front of the engine? I sounds similar to a slipping belt, but not like any other belt I've ever heard. Belts usually slip when first accelerating, not after reaching highway speed.

Are you sure the squeal is coming from the engine? MB put a squealer device in the front hub that touches the main bearing grease cap. When the grease gets dry the squealer starts working letting you know something is wrong.

-m

I beleive that squealer devise is a contact/ground spring to prevent radio noise & static...

also, I just repacked the front wheel bearings two weeks ago.

Check your upper belt pully-wheel. Push and pull it back and forth. If there is play, then you may be due for a new one. I put a dab of Lubro-Molly on my spindle to nurse it along until the replacement arrived. Check it with the engine OFF, of course. :P