An example of such design is a combination of two oil pump housings and two gear sets on the engines of 6.2L (LS3 with RPO Z52 dry sump oiling system), 6.2L (LS9) and 7.0L (LS7) whereas the pressure relief valve is shared. The front gear set adds oil up to the external oil tank and hence is known as the secondary pump while the rear gear set pumps oil directly to the engine hence the primary pump. Start with the removal of the timing chain cover as well as the
Oil Pan as well. Subsequently, unscrew the oil pump pick-up tube mounting nut and the bolt, and as a result the pick-up tube and the screen which will be lowered off the vehicle; in addition, unbolt the other Crankshaft oil deflector bolts together with the deflector. After that, remove the oil pump retaining bolts and slide the pump over the end of the crankshaft. During inspection the oil pump cover is taken off and the rotors pulled out of the pump body, then clean the individual parts with solvent and examine the parts closely, including the bolt holes and splined surfaces of the crankshaft sprocket and observe for visible signs of damage. Any component of this assembly which may have been scored, scratched or worn, will require replacement of the complete oil pump assembly as there were no serviceable subassemblies available at the time of updating this publication. For installation, one must first start running in the pump by pouring fresh engine oil into the pick-up tube hole and while manually operating the pump. Place the oil pump over the extreme end of the crankshaft such that the teeth in the crankshaft sprocket engage on the oil pump drive gear and that of the pump rests on the block. Bolt the oil pump mounting back then tighten to the recommended torque. A new O-ring should be fitted to the pick-up tube of the oil pump, screw this to the oil pump and to the engine block main studs tighten the pick-up tube to oil pump bolts, sufficiently so that no air can get in to the oiling system. The oil pan is then secured back followed by all the other components such as the wheels as installation is done in reverse order of removal in Addition the oil is added before turning the engine on and also the coolant to check for oil and coolant leakage besides checking the oil pressure.