Here's how to change it:
1. Preparation:
* Safety First: Disconnect the negative battery terminal to prevent electrical shorts. Allow the engine to cool completely before starting this process – hot oil is dangerous.
* Gather Supplies: You'll need a wrench (typically a 7/16" or 9/16" – check your existing unit to be sure), some rags or shop towels, a new oil pressure sending unit (make sure you get the correct one for your specific year and engine), and possibly some penetrating oil (like PB Blaster).
2. Accessing the Sending Unit:
* Locate the Unit: Visually inspect the engine block near the oil filter on the driver's side. The sending unit is usually a cylindrical unit with a single or dual wire connector attached.
* Clear Obstructions: You might need to move some wires or hoses to gain better access.
3. Removal:
* Disconnect the Wire(s): Carefully disconnect the wire(s) connected to the sending unit. Take note of how they're connected in case you forget. Some units might have a clip or retaining ring to release the connection, others may just have a wire nut.
* Loosen the Sending Unit: Use the appropriate wrench to carefully loosen and remove the sending unit. It may be somewhat tight due to corrosion. If it's very stubborn, apply penetrating oil and let it sit for a few minutes. Avoid using excessive force, which could damage the threads on the engine block.
* Remove the Unit: Once loosened, unscrew the sending unit by hand. Have a rag ready to catch any residual oil that might leak out.
4. Installation:
* Clean the Threads: Clean the threads on the engine block using a wire brush or appropriate tool. This will ensure a proper seal with the new sending unit.
* Install the New Sending Unit: Carefully screw the new sending unit into the engine block by hand until it's snug. Then, tighten it further with the wrench, being careful not to overtighten. Overtightening can damage the threads. Consult your vehicle's repair manual for the correct torque specification if available.
* Reconnect the Wire(s): Carefully reconnect the wire(s) to the new sending unit, making sure they are securely fastened.
5. Final Checks:
* Check for Leaks: After installation, start the engine and check for any oil leaks around the new sending unit.
* Check the Gauge: Ensure your oil pressure gauge is functioning correctly.
Important Notes:
* Consult a Repair Manual: A repair manual specific to your 1990 Chevy Silverado 350 will provide detailed diagrams and instructions, including torque specifications. This is highly recommended.
* Professional Help: If you're uncomfortable performing this repair yourself, it's best to take your vehicle to a qualified mechanic.
Remember to always prioritize safety when working on your vehicle. If you're not comfortable with any part of this process, seek professional assistance.
