I have recently bought a 97 explorer for my daughter. It has the typical timing chain woes. I first put in the updated front and rear tensioners. Did not fix. So now I have the front of the engine apart and the tensioner/guide for the jack shaft was in 4 pieces. I am going to replace all of the nylon guides while i'm into it. From what I can see their are six all together up front for the three chains. My question is this. I know I can change the four in front easily and I think I can get to the 10mm bolt behind the main jack shaft sprocket with a wrench. Can anyone tell me if I will be able to thread the bolt completly out, and change the guide going up through the cylinder head without taking the chains loose being at risk of the dreaded out of timed valve train. And is the front guide going to head a one or two piece unit? My upper one is in good shape, the lower one seems to be loose. Is it made like this or has it broken away from the upper guide. All the nylon is there on the lower piece, it just moves up and down about a 1/4 inch.