Can I Change my Own Spark Plug Wires and Distributor Cap?

It is very easy to change the distributor cap and spark plug wires. Virtually anyone can do it, and the only tool required is a phillips head screwdriver. White labels or notepaper, a marking pen and Scotch tape might also come in handy. Perform this maintenance when the engine is cold to avoid burning yourself on any hot components.

If you are not familiar with what these parts of your vehicle look like, don’t worry. A local parts store only needs your vehicle’s year and model to find the parts you need. You can also order them online. If you do order online, you will have an opportunity to look at a picture of the parts before ordering. You might want to print a picture of the parts and compare it to the one in your car to make sure it is the correct part.

As long as you're replacing parts, you should also replace the rotor inside the distributor. The rotor, resembling a miniature weather vane, will become visible when you remove the distributor cap. It simply pulls up or off a stem. No tools required. The new rotor presses on the same way, and the part is cheap. The rotor spins a metal arm inside the cap that can become pitted and worn.

Once you acquire the parts to replace your spark plug wires and distributor cap, take a close look at the existing spark plugs in the vehicle. Each spark plug wire plugs into the distributor cap at a specific location on the cap. The only critical rule to follow is that this order be maintained.

The engine fires in a specific succession, which the spark plug wires and distributor cap are set up to support. Most are numbered for clarity. The safest way to change these parts is to unscrew and remove the distributor cap without unplugging any spark plug wires. Note the way the cap is oriented. You might want to tape a note that says “T” at the top of the cap. There will be one extra wire that runs to the ignition coil. Unplug this wire from the cap (leaving it attached at the coil) and tag it with an “IC.” Unscrew the cap, lift it off the distributor, and set it aside by laying in on the engine.

The wedge-shaped, "weathervane" rotor will now be visible, protruding up from the distributor itself. Grip it securely and pull straight up, applying even pressure. The distributor’s rotor stem is slightly flattened on two sides. Look inside the hollow rotor stem of the new part to orient it before pushing it down on to the distributor stem.

Now install the new cap, careful to orient it the same way as the old cap. Replace all four screws and tighten securely.

Remove a single wire from the old cap and from its spark plug. If the wire is numbered, choose the corresponding number from your new kit. If the wires are not numbered, find the right wire by choosing the same length from your new kit. Plugs are various distances from the distributor cap, making them of varying lengths.

Install the new wire on to the spark plug by pushing it down securely. You should feel or hear a pop or snap. Run the new wire to the new distributor cap, following any snap-guides or rubber brackets that might be holding the wires in place along the way. Look at the old cap to be sure you plug the wire into the same location on the new cap. Repeat this procedure for each wire. Finally, install your new ignition coil wire to replace the one you tagged earlier as “IC.”