When should you change the timing chain on an 97 jeep wrangler?

Answer 1

The timing BELT should be replaced every 75,000 miles. I have to assume the previous owner did so at the correct interval. AT 150K+ miles, you're due. If you do, in fact, have a timing CHAIN on a 1997 Jeep 4.0L, it would not need replacement based on mileage alone, but on wear. If you do replace the chain, replace the cam and crank gears also as a complete 3-piece set. Since you have to remove the water pump to get at the timing assembly, it's your call if you want to replace it. It should not be any additional labor, about 2 hours total.

If you just replace the water pump, you can pull the timing cover at that time and see first hand if you have a belt or a chain.

If you have a set of tools and a little mechanical know-how, this is a good afternoon project for the novice mechanic. You will get to know your car better and will be able to understand why repair shops cost so much.