Oil pump replacement instructions?

This is from the front crankshaft seal. I attached the procedure for you with a picture. When you are done, make sure you do the sensor relearn procedure. You will need a scan tool to perform this procedure. Check out the diagrams (Below).

Crankshaft Front Oil Seal Replacement

Tools Required
J 35354-A Seal Installer

Removal Procedure
1. Remove the crankshaft balancer.

2. Pry out the crankshaft front oil seal with a flat bladed tool such as a large screwdriver. Use care to avoid damaging the crankshaft front oil seal bore or the crankshaft front oil seal contact surfaces.

Important: Be careful not to damage the crankshaft.

3. Inspect the crankshaft balancer and engine front cover for scratches.

Installation Procedure

1. Install the crankshaft front oil seal in the engine front cover using the J 35354-A.
2. Tighten the bolt until the crankshaft front oil seal is seated in the engine front cover.
3. Remove the J 35354-A.
4. Install the crankshaft balancer.
5. Inspect for leaks.
6. Perform the CKP system variation learn procedure.

Relearn

CKP SYSTEM VARIATION LEARN PROCEDURE

IMPORTANT:
The scan tool monitors certain component signals to determine if all the conditions are met to continue with the procedure. The scan tool only displays the condition that inhibits the procedure. The scan tool monitors the following components:
Crankshaft position (CKP) sensors activity-If there is a CKP sensor condition, refer to the applicable DTC.
Camshaft position (CMP) signal activity-If there is a CMP signal condition, refer to the applicable DTC.
Engine coolant temperature (ECT)-If the engine coolant temperature is not warm enough, idle the engine until the engine coolant temperature reaches the correct temperature.
The CKP system variation learn procedure is also required when the following service procedures have been performed, regardless of whether DTC P0315 is set:
An engine replacement
A powertrain control module (PCM) replacement
A crankshaft balancer replacement
A crankshaft replacement
A CKP sensor replacement
Any engine repairs which disturb the crankshaft to CKP sensor relationship.

1. Install a scan tool.
2. Monitor the PCM for DTCs with a scan tool. If other DTCs are set, except DTC P0315, refer to Diagnostic Trouble Code (DTC) List - Vehicle for the applicable DTC. See: A L L Diagnostic Trouble Codes ( DTC ) > Diagnostic Trouble Code Descriptions
3. With a scan tool, select the CKP variation learn procedure and perform the following:
1. Observe fuel cut-off for applicable engine.
2. Block drive wheels.
3. Set parking brake.
4. DO NOT apply brake pedal.
5. Cycle ignition from OFF to ON.
6. Apply and hold brake pedal for the duration of the procedure.
7. Start and idle engine.
8. Turn the air conditioning (A/C) OFF.
9. The vehicle must remain in Park or Neutral.
10. Accelerate to wide open throttle (WOT).

IMPORTANT:
The engine should not accelerate beyond the calibrated fuel cut-off RPM value noted in step 3.1. Release the throttle immediately if the value is exceeded.
While the learn procedure is in progress, release the throttle immediately when the engine starts to decelerate. The engine control is returned to the operator and the engine responds to throttle position after the learn procedure is complete.

4. The scan tool displays Learn Status: Learned this ignition. If the scan tool indicates that DTC P0315 ran and passed, the CKP variation learn procedure is complete. If the scan tool indicates DTC P0315 failed or did not run, refer to DTC P0315. If any other DTCs set, refer to Diagnostic Trouble Code (DTC) List - Vehicle for the applicable DTC. See: A L L Diagnostic Trouble Codes ( DTC ) > P Code Charts > P0315 See: A L L Diagnostic Trouble Codes ( DTC ) > Diagnostic Trouble Code Descriptions
5. Turn OFF the ignition for 30 seconds after the learn procedure is completed successfully in order to store the CKP system variation values in the PCM memory.

Check out the diagrams (Below). Please let us know if you need anything else to get the problem fixed.

The only thing I can think they are not packing the oil pump cavity with petroleum jelly. That has to be done to produce a vacuum in the pump to make it start drawing oil. Also, the pick up tube may not have been properly attached. I would think they removed the oil pan to inspect the pick up tube screen to make sure it is not plugged. There is a pressure relief valve that may be an issues as well. I attached a pic below. I highlighted the pressure relief valve and the oil pump gears and backing plate. As far as the used engine they got, it may have had damage prior to install.

As far as needing a new crankshaft position sensor, there is a good chance it was damaged during all this work because of its location. See pic 2. I circled the sensor. You can see it is located at the crankshaft pulley, which is in front of the oil pump.

I need to know this. When they got the new engine, was anything changed on it? For example, did they install the new oil pump from the other engine? Also, (and I realize you are not with the car) if you can record the sound it is making when cranking and upload it for me to hear, it would be helpful. Now that we have a second engine to contend with and we don't know its history, it is going to make things more difficult.

There aren't too many things that can be causing this. I have no idea what they have done so far or what has led to this, especially on two engines.

Let me know

Joe

Happy to help. Let me know what you find out from them.

Joe

3.1L and 3.4L Engines

NOTE
The oil pump is located in the oil pan.

REMOVAL:
Remove the oil pan using the procedure found in this section.
Some engines, such as the may have a crankshaft oil deflector (also called a "windage tray"). Remove the retaining nuts and remove the oil deflector.
Remove the bolt attaching the oil pump to the rear crankshaft bearing cap.
Remove the oil pump and driveshaft.

INSTALLATION:
Clean all parts well. Inspect the driveshaft at both ends for rounding of the corners. Replace, if necessary. If the original pump is being considered for reuse, inspect the pump body and the pump cover for cracks, scoring, casting imperfections, or any obvious damage.
Rotate the pump driveshaft as necessary to engage the with the oil pump. Make sure it turns smoothly. Some technicians will fill the oil pump through the opening next to the driveshaft to shorten the time it take the engine to buildup oil pressure on initial startup after an oil pump replacement. Turning the driveshaft as oil is being added fills the pump cavity.
Install the pump and driveshaft assembly to the engine. Install the retaining bolt and tighten to:
3.1L engines: 30 ft. Lbs. (41 Nm)
3.4L engines: 40 ft. Lbs. (54 Nm)
Install the oil pan using the procedure found in this section.

3.5L Engine

WARNING
As with many procedures on the 3.5L (VIN H) DOHC engine, oil pump removal is a long and complicated task The oil pump is located behind the engine front cover. The engine front cover must be removed. Part of the procedure is lowering the powertrain cradle, or subframe, requiring special lifting and support equipment. The steering shaft must be separated so the vehicle subframe can be loosened and lowered. Careful work is required for reassembly. This is not a job for the inexperienced or ill-equipped. Be very sure of your diagnosis before attempting to remove the oil pump on this engine, especially with the engine still in the vehicle. In addition, a pair of special tools, GM #J 42042 Camshaft Timing Clamps, is required to hold the camshafts in place once the timing chain is removed. This tool, when properly installed, will be fully seated on the camshaft ends with the camshaft flats parallel to the cam cover sealing surfaces. This tool prevents unexpected camshaft rotation caused by valve spring pressure. This tool must be installed immediately after cam cover removal. This engine has no valve timing marks. Once lost, there are no pins or keys to help you re-establish valve timing. If valve timing is lost, it is very difficult to restore.

NOTE
This engine is constructed primarily of aluminum. Use care when working with light alloy parts.

REMOVAL:
Remove the engine front cover using the procedures found in this section.
Remove both camshaft covers. Immediately install Camshaft Holding Fixtures J 42038, or equivalent onto the ends of the camshafts. Rotate the engine to align the camshafts with the tool using the hex on the camshaft and an open end wrench. When installed properly, tool J 42038 will be fully seated on the camshaft ends with the camshaft flats parallel to the cam cover sealing surface.
Remove the oil pan using the procedures found in this section.
Remove the oil pump pipe and screen.
Remove the camshaft drive chain tensioner in order to remove the primary camshaft drive chain from the drive sprocket.
Remove the four oil pump assembly retaining bolts identified by the larger head size.
Slide the oil pump off the nose of the crankshaft with the drive sprocket in place.
Remove the crankshaft sprocket from the oil pump assembly.
Clean all parts well. Please note that the internal parts of this oil pump are not serviced separately. If wear or damage is noted, replace the entire oil pump assembly. To disassemble the pump, use the following procedure:
Remove the eight screws holding the pump housing halves together.
Remove the inner (drive) and the outer (driven) rotors from the housing. Note the orientation of the pump rotors. The outer rotor has a dimple identifying its outer surface. The dimpled side of the outer rotor must always be facing outward.
Remove the threaded pressure relief valve cap and slide the pressure relief spring and valve piston out of the bore.
Clean all pump components with a suitable non-corrosive solvent such as Safety-Kleen, or equivalent.
Dry the oil pump components with compressed air.
Inspect the housing and the cover for nicks, scoring, casting imperfections and damaged threads. Inspect the gerotor gears for chipping, galling or excessive wear. Inspect the pressure relief valve components for embedded particles and/or wear.
Assemble the pump by installing the inner and outer rotors in the pump cover in the same orientation as removed. The outer rotor and a dimple to indicate the outer surface. The dimpled surface must be face-up in the pump body.
Install the pressure relief valve piston first, followed by the spring, in the pump housing bore. Install the valve cap and torque to 97 inch lbs. (11 Nm).
Lubricate the gears with petroleum jelly, packing all the spaces around the gears, filling the pump cavity. This is important. The petroleum jelly seals the pump cavity to help "prime" the pump. The reduces the time the engine will run with little oil pressure on initial start up after oil pump installation. DO NOT use chassis grease because it will clog the oil system passages. Petroleum jelly, after it has accomplished its job of acting as a seal so the pump can prime and draw oil, melts at a low temperature and will "go away" as the engine warms.
Assemble the housing and the cover. Install the bolts and torque to 124 inch lbs. (14 Nm).

INSTALLATION:
Align the crankshaft sprocket splines with the oil pump gerotor and install the sprocket in the oil pump.
Place the pump and sprocket assembly in position by rotating the crankshaft sprocket until the machined slot is indexed with the drive pin in the crankshaft.
Slide the pump and sprocket onto the crankshaft until a positive stop is felt. Make sure the crankshaft sprocket is aligned with the drive pin in the crankshaft. When properly installed, the crankshaft sprocket will protrude from the oil pump but the face of the sprocket will be located behind the machined step in the crankshaft. Align the pump body with the mounting holes in the cylinder block, install the bolts and tighten evenly to 18 ft. Lbs. (25 Nm).
Install the primary camshaft drive chain over the drive sprocket, using the procedures found in this section.
Install the remaining components in the reverse order of removal.

3.8L Engines

NOTE
The oil pump is located inside the engine front cover.

WARNING
When troubleshooting a low oil pressure complaint, another possibility is a clogged screen on the oil pickup pipe, damaged pipe or gasket. The oil pan will have to be removed to check this. Running the engine without measurable oil pressure will cause extensive and expensive damage.

REMOVAL:
Remove the engine front cover using the procedure found in this section.
Remove the oil pump cover attaching screws and remove the cover.
Remove the oil pump gears.
If desired, remove the oil filter adapter and remove the pressure regulator valve and the spring for cleaning.

INSTALLATION:
Clean all parts well.
Lubricate the gears with petroleum jelly, packing all the spaces around the gears, filling the pump cavity. This is important. The petroleum jelly seals the pump cavity to help "prime" the pump. The reduces the time the engine will run with little oil pressure on initial start up after oil pump installation. DO NOT use chassis grease. Petroleum jelly melts at a low temperature and will "go away" as the engine warms.
If the oil pressure relief valve was removed, inspect the valve and bore for burrs. Check the spring for loss of tension. Replace the spring if in doubt.
Install the pump cover and tighten the screws evenly to 98 inch lbs. (11 Nm).
If removed, thoroughly clean the oil pressure relief valve of all varnish and install the spring first, the valve. Use a new oil filter adapter gasket. Install the adapter. Tighten the oil filter adapter bolts evenly to 22 ft. Lbs. (30 Nm).
Install the engine front cover using the procedures found in this section.

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Oil pump is attached to front cover. Remove oil filter pressure regulator and gears from cover. The front cover is probably shot as well and will need replacement. Check out the diagrams (Below). Please let us know if you need anything else to get the problem fixed.