Your mechanic's advice, while well intended, may not be the best, in this case. If you are sure that it's not the serpentine belt, or any related auxiliaries, you may be hearing a problem which requires immediate attention. In the event that it is your water pump, idler, or tensioner bearings, which are all under the timing case covers, (I assume that by right side you are speaking of the passenger side), should one of those freeze up completely, you would suffer a timing belt failure. The engine is what is called an "interference engine", which means that the valves and pistons can collide if the timing belt breaks. That turns your engine into a boat anchor. A very expensive boat anchor. No disrespect intended to a professional mechanic's opinion, but if I were you, I'd seek a second opinion. You may be looking at a $500.00 to $600.00 repair job... if the belt were to break, you could be looking at 5 to 6 THOUSAND.

Marty
'96 855T