- Before servicing the vehicle, refer to the Precautions Section.
- Remove the oil pump from the engine.
- Remove the pump cover attaching screws and the pump cover.
- Mark gear teeth so they may be reassembled with the same teeth indexing. Remove the idler gear, drive gear and shaft from the pump body.
- Remove the pressure regulator valve retaining pin, pressure regulator valve and related parts.
- If the pickup screen and pipe assembly need replacing, mount the pump in a soft-jawed vise and extract the pipe from pump by twisting the assembly as if you are unscrewing the pickup tube from the pump assembly. Do not disturb the pickup screen on the pipe. This is serviced as an assembly.
- Wash all parts in cleaning solvent and dry with compressed air.
Inspect the pump body and cover for cracks or excessive wear. Inspect pump gears for damage or excessive wear.
NOTEThe pump gears and body are not serviced separately. If the pump gears or body are damaged or worn, replacement of the entire oil pump assembly is necessary.
- Check the drive gear shaft for looseness in the pump body. Inspect inside of pump cover for wear that would permit oil to leak past the ends of the gears.
Inspect the pickup screen and pipe assembly for damage to screen, pipe or relief grommet.
Check the pressure regulator valve for fit.
If the pickup screen and pipe assembly was removed, it should be replaced with a new part. Loss of press fit condition could result in an air leak and loss of oil pressure. Mount the pump in a soft-jawed vise, apply sealer to end of pipe, and use a suitable tool to tap the pipe in place.
NOTEBe careful of twisting, shearing or collapsing pipe while installing in pump. Do not use excessive force.
- Install the pressure regulator valve and related parts.
- Install the drive gear and shaft in the pump body.
Install the idler gear in the pump body with the smooth side of gear towards pump cover opening.
NOTEPack the inside of the pump completely with petroleum jelly. DO NOT use engine oil. The pump MUST be primed this way or it won't produce any oil pressure when the engine is started.
- Install the pump cover and torque attaching screws to specifications.
- Turn driveshaft by hand to check for smooth operation.
- Install a new shaft extension clip onto the pump driveshaft and snap the extension shaft into the clip.
Removal & Installation
Before servicing the vehicle, refer to the Precautions Section.
NOTEDisconnecting the negative battery cable on some vehicles may interfere with the functions of the on-board computer systems and may require the computer to undergo a relearning process, once the negative battery cable is reconnected.
- Disconnect the negative battery cable.
- Raise and safely support the vehicle.
- Drain the engine oil.
- Remove the oil pan.
Remove the oil pump-to-rear main bearing cap bolt. Remove the pump and the extension shaft.
Remove the cotter pin, spring and pressure regulator valve.
NOTEPlace your thumb over the pressure regulators bore before removing the cotter pin, as the spring is under pressure.
Assemble pump and extension shaft to rear main bearing cap. Install a new shaft extension with clip onto the pump driveshaft and snap the extension shaft into the clip, then align the slot on top end of extension shaft with drive tang on lower end of distributor drive shaft and install the pump.
NOTEWhen assembling the driveshaft extension to the driveshaft, the end of the extension nearest the washers must be inserted into the driveshaft.
- Insert the driveshaft extension through the opening in the main bearing cap and block until the shaft mates into the distributor drive gear.
- Install the pump onto the rear main bearing cap and install the attaching bolts.
- Tighten bolts to 77 ft. lbs. (105 Nm).
- Install the oil pan and fill the crankcase with engine oil.
- Start the engine and check the oil pressure.
- Using the GM diagnostic scan tool or aftermarket equivalent reprogram the necessary systems and components. Be sure to follow the scan tool manufacturer-s directions.