dave1123

I replaced the timing chain in my 2000 WJ at 235K miles just because the engine seemed a little down in power. The chain guide as gone! The chain itself wasn't badly stretched, just a little loose. Replacing it didn't seem to effect the power at all, it's just tired. Now with 243K miles on it, it has a piston problem. #5 rattles terribly at idle cold but quiets after warm-up. Under heavy load it ticks like detonation. I started running 91 octane to see if it truly WAS detonation, but it's not. With it idling, if you jazz the throttle, you can hear it knock, then quiet down after you release the throttle. Because the body is basically rust free, it's getting a rebuilt short block. The 0331 head has already been replaced.

IDK how familiar you are with the 4.0, but they all rattle at idle cold because the lifters get a little worn and can't keep the valve lash closed until you get the rpm's up. This generally quiets after warm-up, but not always. This is the one fault of this engine's design in that there is no adjustment of the valve lash.

I bought an XJ so I have a back-up vehicle while she is getting her new engine installed and already have almost $2000 invested in it just to get it road worthy! That includes labor costs because I'm not physically capable of crawling under vehicles anymore. That's all new brakes, wheels, tires, muffler & tailpipe, registration and insurance, and original purchase price. It still needs a little frame work.