I have a 96 Sonata that had a blown motor in it. I found a used one with 62000 miles on it and replaced the water pump, timing belt, plugs and wires before installing. When the motor is cold it howls, (growls) from idle to 3000 rpm's then goes away. After the motor is warmed up it just about disapears. It allmost sounds like the cam bearings or somthing in the valve train. Is there any valve train adjustments on this motor? Thanks for any help.

 

Found out it is the timing belt tensioner. Very annoying noise but not a mechanical problem to worry about.