Signs for a new timing chain?

I have a 97 XJ 4.0L with 255,xxx miles on the old Jeep. I have been thinking of what has and hasn't been replaced, also I need to do the remain seal and oil pan gasket AGAIN! 3rd time on this Jeep since I have owned it in the last 13 years, I wish there was a good fix for these rear main seals so they will last more than just a few years.

Anyway, at 255,000 miles, even with the impeccable maintenance I keep on this thing, I'm sure the timing chain is stretched. But what would be some signs that a chain has stretched? I don't have really any strange noises but are there any sort of performance signs?

Yes, just did mine. 2000 XJ nearing 300K. Basically the only sign was at highway speed with the converter locked up, it would feel like I was lugging the motor if I tried to accelerate without downshifting. It was really sluggish. Had to flog the motor to pass someone. WOT it felt pretty normal. Mine was bad enough that it was beginning to contact the cover...I had some metal flakes in the last oil change that concerned me. I was pleasantly surprised when it turned out to be the timing chain cover.

Seat of the pants feel was much better after the new timing chain. YMMV.

I definitely have the lag on the highway but I always thought it was due to the 33s. But like I said it is more than likely due for a change being that it is 17 years old and never been changed.

Idle is a little rougher than I remember when I first got it and I wasn't sure it that might be possibly related. Most other parts that could contribute to rough idle have been recently serviced and I swapped injectors out 3 years ago. But like I said I was just curious if that would be one symptom.

I looked up replacements and saw that they aren't too expensive so I may just try and do this soon.

How bad was it to change out? Did the radiator have to come out? Or just the belt, crank pulley, and timing cover?

It was not terribly bad to change. The radiator does not have to come out, but you will have to remove harmonic balancer and most of the brackets off the front of the motor will have to be removed or loosened.

BTW, my idle was fine.

Take off distributor cap and put a socket on your crank bolt. Turn it by hand and watch your rotor and you'll see how much slop you have. I did my chain at around 160k and there was a lot of slop then. At over 300k now thinking might be time again.

I did my last one because the water pump ate through the cover but that is a different story haha. They aren't hard to change, maybe four hours tops taking your time. Couldn't find a service interval in alldata but I'm sure at that mileage it couldn't hurt at all.

MACH90XJ said:

Take off distributor cap and put a socket on your crank bolt. Turn it by hand and watch your rotor and you'll see how much slop you have. I did my chain at around 160k and there was a lot of slop then. At over 300k now thinking might be time again.

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This is probably the best and easiest test for timing set wear. I'll add to this. Pull the distributor cap and they rotate the engine clock wise to 0* on the timing cover. If you miss the mark you need to rotate counter clockwise at least 15* then clock wise to 0*. Once at 0* rotate the engine counter clockwise until you feel tension from the cam and/or the distributor rotor just slightly moves. Note the degree mark on the timing cover. You might have to do this a few times to get the feel. Anything more than 5* and the timing set should be replaced soon. 7+* and you should replace it now.