General Safety Precautions (Crucial for all engine work):
* Disconnect the negative (-) battery cable before starting any work on the ignition system.
* Wear safety glasses.
* Have the correct spark plug socket and wrench. A spark plug socket with a rubber insert is essential to prevent rounding the spark plug.
* Have a catch pan to collect any oil or debris that might fall out of the spark plug wells.
* Consult a repair manual specific to your 1999 Chevrolet Safari for detailed diagrams and instructions. A Haynes or Chilton manual is a good investment.
Assuming a 4.3L V6 engine:
1. Remove the air cleaner assembly: This usually involves removing a few clamps and unplugging some sensors.
2. Access to the spark plugs might require removal of some other components: Depending on the location of the specific plug, you may need to remove parts like the intake manifold, various hoses, or wiring harnesses. Refer to a repair manual to determine which components need to be removed. It's often easiest to access them from the top of the engine.
3. Locate the spark plug wires: Carefully disconnect the spark plug wires one by one, noting their location. Use a small piece of tape and mark each wire's original location. There is usually a firing order diagram printed on the engine somewhere.
4. Remove the spark plugs: Use the correct spark plug socket and a ratchet or wrench to carefully remove each spark plug.
5. Install the new spark plugs: Make sure the gap is correct (check your vehicle's specifications). Tighten the new spark plugs to the manufacturer's specified torque (see your repair manual). Do not overtighten.
6. Reconnect the spark plug wires: Reconnect the spark plug wires in the correct order.
7. Reassemble everything: Put back all the components you removed in the reverse order of removal.
8. Reconnect the negative (-) battery cable.
Assuming a 5.7L V8 engine:
The process is similar, but access might be even more challenging due to the larger engine. The V8 might require removing more components for access, potentially including additional hoses, brackets, and potentially even part of the exhaust manifold. Refer to a repair manual for a 5.7L V8 specifically.
In short: This is not a simple task and attempting it without proper knowledge and tools could lead to damage. Consult a repair manual for your specific engine for detailed step-by-step instructions, torque specifications, and diagrams. If you are not comfortable performing this task yourself, it's best to take your vehicle to a qualified mechanic.
