This outlines the general steps; specifics may vary slightly depending on your engine (e.g., TBI 350, 454, etc.). Always consult a factory service manual specific to your truck's engine and year for precise instructions and torque specifications.
Tools and Supplies You'll Need:
* Factory Service Manual: Absolutely crucial.
* Engine hoist or stand: You'll likely need to partially or fully remove the engine for easier access.
* Socket set and wrenches (metric and standard): A wide range of sizes will be needed.
* Torque wrench: Essential for proper tightening of bolts.
* Drain pan: For engine oil.
* New oil pump: Make sure it's the correct one for your engine.
* New oil pump gasket(s): These are crucial for a leak-free seal.
* New oil filter: Always change the filter when replacing the pump.
* New oil: The correct type and amount for your engine.
* Jack stands: For safety when working under the vehicle.
* Pry bar: Possibly needed to help remove the oil pump.
* Clean rags: To keep the engine clean.
* Safety glasses and gloves: Protect yourself.
General Steps (Highly Simplified):
1. Safety First: Disconnect the negative battery terminal. Support the vehicle securely on jack stands.
2. Drain the Engine Oil: Completely drain the engine oil into a drain pan.
3. Remove the Oil Pan: This usually involves removing various bolts and potentially some components that may be interfering (like the front cover on some engines). Be prepared for oil spillage.
4. Remove the Oil Pump: The oil pump is usually bolted to the bottom of the engine block. You'll likely need to remove various bolts and possibly use a pry bar (carefully!) to help release the pump. Take note of the position of all components to facilitate reassembly.
5. Install the New Oil Pump: Carefully install the new oil pump gasket(s), install the new oil pump, ensuring it's properly seated. Tighten bolts to the manufacturer's specified torque.
6. Reinstall the Oil Pan: Carefully reinstall the oil pan, ensuring the gasket is properly seated. Tighten the bolts to the correct torque specification.
7. Refill with Oil: Refill the engine with the correct type and amount of oil.
8. Replace the Oil Filter: Install the new oil filter.
9. Reconnect the Battery: Reconnect the negative battery terminal.
10. Start the Engine: Start the engine and check for leaks. Monitor the oil pressure gauge. If the oil pressure is low or there are leaks, you'll need to investigate and correct the problem before driving.
11. Check Oil Level: After a short run, check the oil level and add more if needed.
Important Considerations:
* Engine Removal: Depending on your engine and access, partial or complete engine removal might be necessary for easier access to the oil pump.
* Timing Chain/Gears: On some engines, removing the oil pump may require disconnecting the timing chain or gears. This is a very precise and critical operation; if you're unfamiliar, seeking professional help is strongly recommended.
* Torque Specifications: Following the torque specifications from your factory service manual is crucial for preventing damage.
* Gaskets and Seals: Use only new gaskets and seals to prevent leaks.
Again, this is a simplified overview. A factory service manual for your specific 1990 Chevy Silverado 2500 is absolutely necessary. This repair is complex and potentially damaging if done improperly. If you are not experienced with engine repair, it is highly recommended to have a qualified mechanic perform this work.
