First off I can't thank you enough for posting this information. I saved this thread so that I can read over it again and look at the pictures several times so I know what I'm looking at ahead of time. Started several weeks ago I noticed a rattling sound from my 97 Explorer 4.0 V6, Auto, 4WD. At first it wasn't all that bad and it sounded like an exhaust rattle, except the sound appeared to be coming from the driver side exhaust manifold. Just a couple days ago I noticed after the truck had set and idled for about 15 minutes the rattle was starting to get really loud. If I reved up the engine the noise would quit. I assume it was oil pressure building and the chain was tightening up. The noise definately sounds like it is coming from the driver side area, maybe under or behind the EGR. It looks like I am going to have no choice but to pull the intake manifold off and take a look at the tensioner for the driver side. From the looks of the picture you posted, I should be able to view the plastic guide as well. If the guide is broke or all chewed up then I guess I have no choice but to tear down the front of the engine. Otherwise I will replace the tensioner only and see IF that fixes the problem. _____________ Right now the engine is running fine, except for the rattle which only happens at certain times. IF I have to tear down the engine and replace the tensioners, guides, etc. do I have to remove the chains to do this? Since the engine is running fine right now, and thus the timing hasn't taken a walk on me yet, it would be great if I could leave the chains on to avoid having to reset the timing. Can I just replace the guides and tensioners? If not, is it true I have to have special tools to reset the timing? If I do have to reset the timing, does the engine have to come out in order to use the special tools to set the timing? I hate the idea of having to pull the engine out just to reset timing. If I had to do that I might as well rebuild the whole engine. I've always liked Ford vehicles, but when it comes to the timing on this engine Ford needs a good kick in the rear end.