Changing the plugs out in this type of engine is not hard to do...once you figure out where they're at! If you're looking at your engine from the front of your jeep, you'll find the plugs on the passenger side near the top of the engine. The plugs are hidden underneath a coil pack (I think that's what it's called) secured by 4 head bolts. The coil pack is black, about 18 inches long and about 2.5 inches wide and is attached to the engine at a 45 degree angle. It's directly beside your engine oil dipstick.
Take the 4 bolts out (13mm socket), pull the pack off and remove and replace the plugs. The only other advice that I'd give you is to use the OE Champion plugs. I know they don't have the best reputation, but they are the plugs the jeeps's I6 were designed around and work best in my opinion. I've tried Bosch plat's, autolite, ac delco and the champion's produced the smoothest idle and best performance in the jeep.
Originally Posted by baseball_coach
My 2000 GC has 40,000 miles on it and I would like to change the spark plugs in the I-6 engine. I am no mechanic but have manage to do this type of work on all the vehicles that I have owned. The only problem with this job is I have not been able to even find the location of the plugs in the motor to determine if this is something I should take on. Can someone advise me on this or provide a website with pictures or instructions. This may be a jop for the dealer. Thanks in advace.