How to Replace Spark Plugs on a 4.6 Ford Engine

by Carl PruitUpdated November 07, 2017

Items you will need

  • open end wrench

  • Socket wrench set

  • screwdriver

  • liquid wrench

  • spark plug wrench

  • spark plug gapper

  • spark plugs

The Ford 4.6 engine is a big block motor, designed to fit in some of the larger Ford vehicles such as an Expedition or F-150 pickup truck. It is made for heavy-duty use and because of this, it is critical that you maintain a regular schedule of maintenance and tune-ups. Consult your owners manual for the guidelines on how often you should replace the spark plugs on a 4.6 Ford engine. If you notice smoke coming from your tailpipe after the vehicle is warmed up, this could be an indication that your spark plugs are worn out or that the gap is set incorrectly.

Remove the negative battery cable from the battery with an open end wrench and place it in a position so that it will not touch any metal parts. Locate the position of the spark plug wires on the 4.6 ford engine. This will show you were the spark plugs are located.

Detach the black cover that is over the throttle body. It is held in place by 3 10mm bolts and the cover will say "4.6" on it. Remove the air intake tube under the cover by loosening the clamps on the hoses at either end with a screwdriver and pulling the hoses off that are attached to the unit. Pull it out of the way and place in a safe location.

Remove the brace that runs from the power steering reservoir to the thermostat housing. The brace is attached by 3 8 mm screws. Remove it and place to the side. This will give you a clear area to remove the spark plugs from the motor.

Remove the coil-on-plug (cop) assemblies that are over each spark plug with a 7mm socket wrench. For better access, use a socket extension on your ratchet. Tag each coil with masking tap and label it so that you can remember which coil went on which spark plug.

Spray a small amount of liquid wrench over the top of each spark plug to loosen them up. Use a spark plug wrench to remove each of the plugs from the engine block.

Set the gap on each of the new spark plugs with a gap tool. For the exact plug gap, see the owners manual for your Ford 4.6 engine. Install the new plugs into the engine block with a spark plug wrench.

Reattach the coil-on-plug assemblies and then attach the brace that runs from the power steering reservoir to the thermostat housing. Secure the air intake tube by placing the hoses over both ends of the tube and tightening the clamps with a screwdriver.

Reattach the black cover over the throttle body with bolts and then attach the negative battery cable to the battery.


Be careful not to over-tighten the spark plugs as you install them or it could result in you cracking the plugs.

  • Do not attempt to change the spark plugs on an engine that is hot. Allow it to cool before doing any mechanical work.

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