How often should you change the spark plugs on a 2004 jeep liberty 3.7 L?
They should not need changing until 90,000 miles.
30,000 miles is recommended for spark plug replacement on all Chrysler/Jeep vehicles, not just the Jeep Liberty. Not only are plugs recommended at 30,000 miles, shock absorbers are recommended as well. As a mechanic for the Chrysler/Jeep Corp., i can say with confidence that it is not entirely necessary to change plugs and shocks at the 30k mile mark. Basically, "If it ain't broke, don't fix it!" (however, i do recommend at least checking the…
Plug leads should last 3 or 4 times as long as plugs. They do not always abide by the rules, however. If you are running wonky and new plugs doesn't fix it, try new leads, it often works. If it does, put the old plugs back in with the new leads. I bet you will have a spare set of fresh plugs for another day.
The best answer is to follow the recommendations for maintenance in your particular car's owner's manual. A rule of thumb is every 30,000 miles for standard plugs and 60,000 for platinum or other precious metal plugs. Don't forget the ignition system's secondary wiring. Worn plugs and damaged wires can cause ignition coils and other ignition components to fail prematurely.