I have a 2001 Silverado 1500 2wd 4.8 with a real nasty squeal coming from the from the front of the motor. It sounds like a belt slipping, but that is not the case. It gets louder with more RPMs. I have already performed the following: new serp belt new tensioner new idler pulley new a/c belt new a/c tensioner new water pump new fan clutch The noise still persists. I have isolated the noise to the water pump/crank pulley area. Could it be the oil pump?