The lower hose on my radiator came off about a week ago and it was towed to the dealer where it was replaced. However the truck began making this whistling noise periodically and just recently the steering has become hard as if it has no power steering... When you initially start the vehicle the steering works fine until you out it in gear and then it becomes difficult to turn. Any suggestions?

 

So, what have you checked so far??? Have you checked your fluid level, if low again, you still have a leak, if not low then most likely the pump has failed.

 

I've checked the fluid and all seem well....if the pump has failed would it allow the steerimg to work on a cold start and then fail.... I read somewhere about a servo valve?

 

Was the belt doused with coolant?
If so it may need to be replaced, it will slip and you will not have any power steering or the like.