On 3. SL engines, this operation can only be done when the engine is out of the car although one hopes that the new 3. All the steps that do not apply since SL engine has been removed should be completely disregarded. To start with, you should disconnect the
Oil Pan, as well as the oil screen pick-up tube assembly. Then, take off the
Timing Chain cover, timing chains, crankshaft sprockets and so on. Each of the four oil pump mounting bolts can be loosened one full turn before gradually and evenly turning each of the bolts many times. After all the bolts have been loosened, take out the bolts and the oil pump also, when doing this should rotate the oil housing in a clockwise direction in 3.5 L engines in order to detach the oil housing from the oil pickup tube. Continue to pull out the following parts; the oil pump cover should be detached from the pump body, the identification marks on the rotors noted as they are pulled out. Rinse and dry all related parts, which is to check the surface of the rotors for wear and or damage; if there is score mark or other sort of damage on rotors, pump body or cover, then it requires changing the entire oil pump assembly. If the components are acceptable, dip the rotors in clean engine oil and reassemble them to the pump body; make sure the identification mark fits as mentioned above. Screw the cover for added stability and proper fixing. For installation, turn the inner rotor of oil pump to the crankshaft where the flats are provided and place the pump over the crankshaft appropriately unto the cylinder block where it will engage with the block tightly. For 3.5 L engines, the pump assembly has to be rotated in anti-clockwise direction to locate the pump assembly near the O-ring of the oil pick up tube. Screw the oil pump bolts till they get tighten by hand and then using parallel pattern tighten up to the torque then tighten four by four sequence until the torque is met. The rest of the installation is a complete mirror image of the removal process outlined above. Last but not the least, replace the engine oil and add a fresh filter and start the engine, scanning for any signs of leaks.