Here's a general outline of the process. Specifics may vary slightly depending on your exact S-10 model and any modifications. Always consult a repair manual specific to your year and model for precise instructions and torque specifications. A Haynes or Chilton manual is a good investment.
Tools You'll Likely Need:
* Socket wrench set (metric): Including a variety of sizes and extensions.
* Wrench set (metric): For various bolt sizes.
* Crankshaft pulley puller: Essential for removing the pulley without damaging it. Different pullers exist; choose one appropriate for your vehicle.
* Torque wrench: Crucial for tightening bolts to the correct specifications.
* Jack and jack stands: To safely lift the vehicle.
* Wheel chocks: For safety.
* Ratchet and sockets: To remove and install bolts.
* Penetrating oil (like PB Blaster): To help loosen stubborn bolts.
* Gloves: Protect your hands.
* Safety glasses: Protect your eyes.
Procedure:
1. Safety First: Disconnect the negative battery cable. Chock the rear wheels and safely raise the front of the truck using a jack and jack stands.
2. Access the Crankshaft Pulley: Locate the crankshaft pulley at the front of the engine. You'll likely need to remove the serpentine belt first. This usually involves loosening the tensioner pulley. Consult your repair manual for the specific procedure.
3. Remove the Crankshaft Pulley Bolt: This is often a very large bolt and can be extremely tight. Use a breaker bar and the correct socket to loosen and remove it. Penetrating oil beforehand is highly recommended. Sometimes, you may need to hold the crankshaft from turning with a wrench on the crankshaft bolt while you remove the pulley bolt.
4. Use the Pulley Puller: Carefully install the crankshaft pulley puller according to its instructions. Tighten the puller until the pulley is removed from the crankshaft. This can be difficult and may require significant force.
5. Installation of the New Pulley: Align the new pulley with the crankshaft. Carefully slide it onto the crankshaft. Make sure it's fully seated.
6. Install the Crankshaft Pulley Bolt: Thread the crankshaft pulley bolt by hand first, then tighten it securely using a torque wrench. Absolutely crucial to tighten to the correct torque specification as found in your repair manual.
7. Reinstall the Serpentine Belt: Reinstall the serpentine belt, making sure it's correctly routed over all the pulleys.
8. Reconnect the Battery Cable: Reconnect the negative battery cable.
9. Lower the Vehicle: Carefully lower the vehicle from the jack stands.
10. Test: Start the engine and check for any noises or leaks. Double-check that the serpentine belt is properly aligned and tensioned.
Important Considerations:
* Harmonic Balancer: The crankshaft pulley is sometimes combined with a harmonic balancer. If your pulley is integrated with the balancer, replacing it may require more specialized tools and expertise. Replacing just the pulley without addressing a damaged balancer might lead to future problems.
* Torque Specifications: Following the correct torque specifications is paramount to prevent damage to the crankshaft or pulley.
* Pulley Alignment: Ensure the new pulley is properly aligned before tightening the bolt.
Again, this is a simplified overview. Refer to a repair manual specific to your 1991 Chevy S-10 4.3L for detailed instructions and torque specifications. If you're uncomfortable with any step, seeking professional help is the safest option. Incorrectly installing the pulley could lead to engine damage.
