Grinding while hubs are locked in?

[mbollich]

So I have a 91 ford explorer. When i lock my hubs in and leave it in 2wd i hear a noise (almost want to say grinding, but it could be a loud humming) when i go faster than 25 to 30 mph. When i engage 4hi the noise gets quieter but does not go away. This happens wile driving straight and turning. I know the 4wd works but im not sure if this is normal. Any insight would be greatly appreciated.

Thanks

 

[wood1]

Start checking your u-joints, front driveshaft and front axles.

Welcome to the site dude!