noise after replacing oil pump and timing belt, Frontier
 

I hope someone can help me out here before I have to take my truck to a shop.
This weekend my husband had to change the oil pump on my 2000 Nissan Frontier. While he had everything torn down he decided to replace the timing belt also because it had 171,000 miles on it. Anyway, after all was complete and put back together we noticed a whining noise. Sounds like it could be a pulley or belt misalignment but can not find a culprit. We also thought it could possibly be the seal in the new oil pump because it was very tight going on. Everything is working great, no problems with timing or oil flow/pressure. It's just noise. So the belt and pump must be fine, right?
The noise sounds almost like something is in a bind. But we can't find anything! Belts are right, pulleys seem to be in alignment, belts are in good shape. No parts left off :eek:.
If anyone has ever had a similar problem, please post. This noise is driving me crazy!

Thanks in advance,
Angela
P.S. this is a 3.3L V6 engine.