Hyundai Repair: Roaring noise and hesitation, hyundai santa fe, balance shaft

Question
I have a 2001 Hyundai Santa Fe with a 4 cylinder engine.  I recently had the timing and pulley belts and water pump replaced.  My car now makes a loud roaring noise and sometimes hesitates during acceleration. Do you have any idea what the problem is?

Answer
As I don't have the capability of inspecting your vehicle, it'll be difficult for me to tell you what the problem is, but I can give you some possibilities.  Presuming the problem was not present prior to servicing and was present immediately after servicing, I'd suspect the following:

If either of the camshafts are timed incorrectly, this will cause a rough idle when warm and in some cases a lack of performance.

If a balance shaft is timed incorrectly, this will cause a high frequency vibration.  Some people report this as a humming type noise.