The Ford Thunderbird was introduced in 1955. The 1989 model was available as a base model, LX and Super Coupe. The base model and the LX were equipped with a 3.8-liter V-6 engine that produced 140 horsepower. The Super Coupe was equipped with a 3.8-liter supercharged V-6 that produced 210 horsepower. The spark plug replacement procedures are the same for both engines. Replacing the spark plugs individually will help ensure you do not mix up the wires or the firing order.
Instructions
- 1
Open the hood on the Thunderbird. Remove the negative battery cable from the battery using a ratchet and socket.
2Remove a single spark plug wire from one of the spark plugs by twisting the boot with your hand. Use a set of spark plug boot pliers if needed. Do not pull the spark plug wire off of the plug by the wire itself or you could damage the end of the wire.
3Remove the spark plug from the engine using a 3/8-inch-drive spark plug socket, extension and ratchet. Turn the spark plug counterclockwise to loosen and remove the plug.
4Measure the plug gap on your new spark plug using a wire feeler gauge or spark plug gap tool. Set the gap between the metal ground arc and the diode to 0.054 using your gap tool. Some spark plug gaps are not adjustable, depending on the plug type. Read the spark plug packaging carefully so you do not damage the plug. If the plug is not adjustable and you need a different plug gap, return the plugs to your parts supplier and tell them the specific plug gap you need.
5Remove the extension and spark plug socket together from the ratchet. Insert the new spark plug into the spark plug socket. Install the plug into the engine by hand to ensure proper threading of the plug. Tighten the plug between 5 and 11 foot-pounds, using a 1/2-inch torque wrench, an adapter and your extension and spark plug socket.
6Install a small amount of dielectric grease into the spark plug wire end. Insert the wire onto the plug and press the wire until it clicks into place. Tug the wire slightly to ensure your plug wire has a good grip on the spark plug.
7Repeat Steps 2 through 6 to complete each individual spark plug. Use a swivel socket or U-joint socket for the rear driver's side plugs, to maneuver around the steering shaft if needed. Inspect the spark plug wires as you go for cracks or exposed wire insulation. Replace all of the wires as a set if you find any faulty wires. Install the negative battery cable onto the battery when you have completed the spark plug replacement. Tighten the battery cable with a ratchet and socket.
