Hyundai Repair: 2001 Sonata-belts, balance shaft, nut bolt

Question
We've recently had all the belts in our Sonata changed out. We're now getting a clattering sound. We took it back to the shop a few times, they replaced teh Alt/AC belt, retightened a few times. It will be quiet in the shop, but the 'clattering' starts up after a few miles of driving. Aany ideas what may be causing this? My hubby thinks it is linked to the belt tension adjustement bolt. He can tighten it a bit, and it sounds a little better, but just for a short while. Also, on hot days, we don't hear it. Also, since we had the timing belt replaced as well, we have a little 'jumpy' feeling at idle. Its pretty subtle, but still noticable and new. I wonder if this is linked to teh new timing belt? It's kinda like a 'hiccup' in the idle at a certain point. Thanks for any insight!

Answer
Based on your description, I'm presuming you have the 2.4L four cylinder engine.  Considering that presumption, you have two timing belts: a main timing belt and a balance shaft belt.  You also have two drive belts: one for A/C and power steering and another for the alternator and water pump.

The fact that tightening the belt changes the noise suggests that the noise is indeed coming from the belt.  One thought is that the clamping nut/bolt may not be tight, allowing the adjuster bolt to back out and release tension.

It's also possible that the "jumpy" feeling is due to improper timing belt installation.  If one of the camshafts is a tooth off, a rough idle when the engine is warm may result.

Of course, the problem is that I can't form any good opinions without hearing and feeling the problems.  Since this shop has been unable to locate the problem, perhaps give them one last chance.  Indicate that if they cannot find the problem and fix it, that you'll take the car to the dealer and expect them to pay for any repairs that resulted from improper repairs on their part.  Then, if the problem isn't repaired, take the car to the dealer and be sure to advise them of the work that was done and that these issues started after the work.  The dealer should know what the vehicle normally feels like, and the additional information will help them identify items to look for.