I have a 1999 Chevrolet Suburban with 201000 miles and I noticed there's a grinding sound coming from the front end when it's on drive I can hear up to about 30 but then the motor is louder than the grinding so I can't hear it. Any ideas?

 

brakes or wheel bearing maybe...more details?

 

Well today I changed the brakes and rotors in the front. I had a guy look at it and he said that's what it was he wanted $400 to do it. I did it myself and only cost $80 in parts. They needed to be done it still sounds like its grinding. Any ideas what it could be? It does it only when driving and in 4wd as well. But it stops when I stop.

 

front diff could be low on oil...

that many miles depending on how it was used the front diff could be wearing out.

 

It would be almost impossible to diagnose a noise without hearing it. We could guess many parts but the fact is they are only a guess. Each persons description of a noise maybe different. A grind to you maybe a squeak or a rubbing noise to someone else. A forum is the wrong place to get help with a noise. Just because person "A" had a noise that was the front diff does not mean every "grinding noise " everyone else had is the same thing. If you paid the guy to tell you it was the brakes then take it back to him. If he did it for free then you got exactly what you paid for. Sorry but I am just keeping it real. If you can not find it yourself then you need to pay someone qualified to find it for you.

 

I would have to agree with MDTAHOE's everyone's version of grinding vs rubbing...
You could try getting it up off the ground and spin each wheel..
might even try putting it in gear while securely and properly supported off the ground in both 2 and 4 wheel mode....