Alright. Well lucky for yall there are TONS of threads on here about the dreaded timing chain rattle. 2000StreetRod has many posts here:
http://www.explorerforum.com/forums/showthread.php?p=2349038
Now. If you have timing chain rattle you have options, as it says in the posts on that link, the first thing to do is your tensioners. Part numbers are in those threads. The front one take 4-5 hours to do because you MUST remove the upper intake manifold, and the litte bronze sensor in your thermostat housing that almost ALWAYS breaks. I was lucky enough to get it out in one piece. But it must come out, you don't have enough clearance to get the replacement tensioner in. Now, the FRONT tensioner cost $135 directly from FORD (you can't get it anywhere else unless you want to go on ebay). The metal compression ring cost 13 bucks. The rear tensioner is MUCH EASIER to do and only $105 (from ford again). Jack the car up, take the passenger front wheel off, and get an extension with a socket on the end and go for it. Took me literally 10 minutes from getting the wheel off to putting it back on! If you still have rattle (which I do but not bad) try using thicker oil or go synthetic. It has different properties that coat things better.
Here's the sad thing. I have done all this, AFTER doing a motor swap because the old engine was dinked from timing chain issues (260K). Now, the awd (auto 4x4) explorers have 4 chains total. One long one in the back, one going from crank to jackshaft and from jackshaft to drivers side head, and then one little guy on the bottom. There are options for doing the front, you can either take the rads and basically the whole front end of the motor apart and the lower and upper oil pan, and the intake manifold off, OR remove the motor and do it there. The rear chain you have two options, remove the motor, or drop the tranny. So you might as well just pull the motor and do it all out of the truck. If you are lucky enough to find the parts on ebay you can get them cheap. (no truck parts are cheap here in canada and shipping isnt cheap here either). Anyways. You can order the whole complete kit for $1400 bucks. Too bad that doesnt include all the gaskets you are going to need to put it all back together and the timing tool kit to do the camshaft timing. I took the other route. I bought a used engine from the auto wreckers (had 120K on it) for 800 bucks. And did a motor swap. I did all of the work myself which i guarantee saved me over 1000 bucks. Now, it would take a mechanic 8 hours minimum to remove the engine, then another 10 hours to tear the engine apart to replace all chains and put it all back together, and then 6 hours to throw the engine back in. 25 hours MINIMUM to do the whole thing at a shop, and shops are 100 buck an hour. Do the math. It's still cheaper to get a new motor and have a shop put it in. Or, do it all yourself like i did (motor swap anyways) and save yourself a TON of money. Sorry for the essay, but I figure I will share my experience. Also, if you do a motor swap, get a 4.0 sohc from a 3rd gen (2002 or later) because the timing chain problems are fixed in those motors.
