[Spun01]

Hello all. I have a growing concern towards a sort of "drum beat" sound coming
from somewhere either on top or behind the fan. The sound is like a fast thu..thu..thud which can be heard at idle and sometimes on accellaration. It is so noticeable that I almost don't want to drive it that much until I figure out what it is. It began after I had my car washed. What should I do? Can anybody help me? I would greatly appreciate any advice or information. I hope it is not serious. Thanks in advance....