Started to hear a rather loud rattling sound from from the engine only at idle if I gas it up it goes away and sounds smooth. . Now being a mechanic for 15 years I feel stupid because I jumped the gun did absolutely no diag work and pulled the engine and wish I had at least listened with a stethoscope but it did skunt like it came from the back of the engine I thought maybe it was a spun bearing, I had 3 torque converter bolts loose, took the timing cover off and the chain in extremely loose however I don't see any marking or indication of it slapping around. I've currently pulled 3 rod caps so far and all of the bearings are good no indication of damage but I still have several to go. I'm curious has anyone else this problem? I don't want to replace the engine if I don't have to although at this point it's already out and I feel I midas well just do it. I have a 5.9 available that runs good for cheap. The extra lower would be nice anyways since I have the 5.2 and I'm running 35s with a lift kit. But has anyone had this issue? Would the timing chain loose cause a rattle without any marking.? Would the loose bolts on the torque converter cause that noise? I didn't see any visible markings on the fly wheel or anywhere in the housing to indicate that's the issue. Any recommendations? Any one with the same issue before and what fixed it? I'm already going to replace the timing chain . I don't feel any play with any of the rocker arms and all the push rods are straight. I haven't taken them rockers off yet I don't feel the need to... Any ideas or just say screw it and throw a new engine in it?

 

Loose bolts on the torque converter would most certainly make some interesting noises......

 

I would agree, loose converter bolts would definitely make some ruckus, as you stated the engine now out so if swapping was a plan now would be the time. I've always been told the 5.2 and 5.9 use different torque converters so that would also be an expense to account for. Personally I've always preferred the 5.2 but I would imagine that the extra low end from the 5.9 would be beneficial