GM 12656337 Pump Assembly, Oil

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Loosen the right-front wheel lug nuts, raise the front of the vehicle, and support it securely on jackstands before removing the right front wheel. Next, remove the drivebelt and drain the engine oil. Proceed to remove the engine front cover by taking out the four bolts retaining the round gerotor cover from the engine cover. On the rear of the engine cover, loosen the oil pump cover screws gradually until they are all loose, then remove the cover. Note any identification marks on the rotors and withdraw them from the pump body; if no marks are visible, use a permanent marker to create your own for correct installation. Clean and dry the components thoroughly, inspecting the rotors for wear or damage. If any rotor, the pump body, or the cover is scored or damaged, replace the complete oil pump assembly. Check the inner-to-outer rotor tip clearance, the outer rotor-to-housing clearance, and the rotor-to-cover side clearance. If the oil pump components are acceptable, dip the rotors in clean engine oil and install them into the pump body with the identification marks positioned as noted during disassembly. Remove the oil pressure relief valve components from the front cover, clean and dry them, and inspect for wear or damage before installing them in the correct order. Install the rotors into the housing with the hub of the inner rotor facing the engine front cover, ensuring the inner rotor hub is installed correctly for proper fastening of the engine front cover/gerotor cover. Install the oil pump cover and screws, tightening them by hand until snug, then gradually and evenly to the specified torque, followed by the installation of the oil pressure relief valve components. Fill the engine with fresh engine oil and install a new oil filler. Start the engine and check for leaks, ensuring that oil pressure comes up to normal quickly; if it doesn't, stop the engine and investigate the cause to prevent severe engine damage from insufficient oil pressure.

On the rear of the oil pump, loosen the oil pump cover screws gradually and remove the cover.

Apply a bead of anaerobic sealant to the oil pump flange and the threads of the mounting bolts, ensuring parts are assembled within five minutes of sealant application.