timing chain slapping?

2000 cherokee, 4.0L, AW4, 242TC, 89,000 miles: i've been searching but haven't found anything exactly like what i'm experiencing. when i take off from a standstill, especially with with a payload, i get a grinding or rattling noise coming from in front of the engine, definitely not the TC. it dies down and eventually flutters away after enough momemtum/speed and doesn't seem to effect performance. is there a tensioner for the timing chain that could be faulty and slapping or is the timing chain just shot already? i thought about the fan hitting the shroud or a broken motor mount, but all seem to be ok. if anybody has had this experience i could use some advice before i do an exploratory teardown.

I haven't heard of many timing chain issues, so I would look elsewhere first. Front ds, front axle, front brakes, loose body pieces.....etc.

Think I read the other day that the stock chains will go 300K+

I'd look for a busted motor mount, only when your on the torque does the fan touch the shroud. It's probably the motor lifting off the one the rubber busted on. If you could hear the timing chain slap it probably would have jumped time and you'd know it for certain. Just scratch that one off if it still idles the same.

Jess said:

I haven't heard of many timing chain issues, so I would look elsewhere first. Front ds, front axle, front brakes, loose body pieces.....etc.

Think I read the other day that the stock chains will go 300K+

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I think thats a bit exaggerated- Jon I'm looking in your direction. But, they are very durable and your Jeep seems like a low mileage example.

I think its far more likely that your fan is hitting the shroud or possibly radiator. This is fairly common and on these and I think is caused by motor mount failure. You can't really get a good look at the mounts without taking them off. The other parts mentioned are good suggestions. Driveline noises can travel BTW and sometimes sound like the are coming from somewhere else.

DUH I didn't scroll far enough to see your last line, sorry bout that

wow, thanks for all the quick responses. i'll have to check deeper into the motor mounts. which one would be more suspect, drivers side or passenger? wouldn't torque influence engine movement more one way than the other? i'm thinking the engine would tend to push on one and lift on the other, but i guess either could have a similar effect. might be easier to remove the shroud and see if the noise goes away. that would help determine if there's movement. thanks again guys.

i thought i had the same thing even went to aamco to have the transfer case looked at and they said it was making noise. come to find out it was the cardan joint in the front driveshaft. took it off and drove around, noise was gone so i would do that before changing parts.

mystery solved and thanks to everyone for all the advice. turns out Bahacalal was right on the money. after further searching into the dark abyss around the fan shroud, i saw that one of the tabs in the bottom of the shroud was not in its slot allowing movement. must have been overlooked at DC when it was built since i've never had the shroud removed for anything. probably just took this long to flex enough to allow interfernce with the fan. anyway noise is gone. thanks again, this a great site and i'll be sure to use it often.