The Toyota Highlander is available in three different engine sizes: 2.4, 3.0 and 3.3 liter. The basic technique for replacing spark plugs is used for both engine sizes, but depending on the engine size you need to remove different parts from the Toyota Highlander to gain access to the spark plugs.
- 1 Pull the hood release and raise the hood on the Highlander. Allow the engine plenty of time to cool.
- 2 Remove some components to reach the spark plugs. On a 3.3 liter engine, unscrew and remove the V-bank cover and intake air tank. On a 2.4 and 3.0 liter engine, remove the number one engine cover.
- 3 Locate the ignition coils and spark plug wires that connect directly to the spark plugs or directly to the engine in the Toyota Highlander. In 2001 and 2002 models, theses are on the front and back of the engine. On models made after 2002, the spark plugs are along the sides. Grab the ignition coils or spark plug wires by the thick plastic piece at the end of the wire. Squeeze the end and turn it to release it from the spark plug. Pull back to remove the plug from the engine.
- 4 Slide the spark plug socket over the spark plug. The most common size of spark plug socket used on a Toyota Highlander is 16mm. Turn the socket to the left to unscrew and remove the spark plug from the cylinder well.
- 5 Apply a thin coat of anti-seize compound to the spark plug thread and into the wire boot to reduce the chance of sticking.
- 6 Insert the spark plug into the well and manually turn the plug into place. If you cannot reach the plug well manually, insert the plug into the socket and extension and use the extension to turn the plug into place. Do not use a socket wrench or flexible extension for this process because their force damages the spark plug.
- 7 Connect the ignition coil or spark plug wire to the spark plug. Turn to lock it into place.
- 8 Continue this process for the rest of the spark plugs. Replace any removed items onto the engine and lower the hood.