How to Replace Spark Plugs in a Jeep Grand Cherokee

The Jeep Grand Cherokee is available in two different size engines: the 4.0 liter and the 4.7 liter. Be sure to buy the correct spark plug for these engines because each engine requires a different type of spark plug. Jeep Grand Cherokee spark plugs need to be changed every 30,000 to 60,000 miles.

Instructions

1

Disconnect the negative battery cable so the Cherokee doesn't accidentally turn on while you change the spark plugs.

2

Locate the spark plug wires in the Cherokee cylinder head. In the 4.0 liter engine, the spark plugs are below the coil rail assembly. On the 4.7 liter engine, the spark plugs are located under each corresponding engine coil.

3

Grasp the spark plug wire firmly at the boot. Turn the wire boot to release the lock and pull back on the boot to remove the wire.

4

Use the socket and wrench to remove the spark plug from the cylinder head. Turn the socket counter-clockwise to unscrew the spark plug.

5

Spread anti-seize compound over the threads of the new spark plug. Anti-seize compound or equivalent lubricant is available at any auto parts store.

6

Begin to manually screw the new spark plug into the cylinder head. Finish tightening the spark plug with the socket, if necessary.

7

Check and adjust the tension on the spark plug. The tension testing tool displays the tension on the spark plug. The appropriate amount of tension is listed on the plug's packaging. Depending on the type of spark plug, the tension ranges from 20 to 35 foot pounds. Some V8 spark plugs require an o-ring to complete the installation. Read the package for instructions and needed materials.

8

Place the spark plug wire's boot onto the spark plug. Turn it gently from side to side to lock the spark plug into place.

9

Repeat Steps 2 through 8 for the other spark plugs. Do not remove all of the spark plug wires at one time. If a spark plug wire is placed on the wrong cylinder, it may damage the engine.