About 6 months ago, my uncle was driving his 98 Dodge Grand Caravan with the 3.0L motor in it, when the water pump seized. The water pump in the 3.0L is driven off the timing belt, so it killed the timing belt and tensioner while it was at it. My uncle and I replaced the water pump, timing belt, and timing belt tensioner. We timed the motor according to the Dodge factory shop manual. When we went to start it up, it started, made a horrific clatter/racket, then promptly died. Ugh. So, we tested the cylinders for compression, and found that one cylinder had low compression. We pulled the front head with the offending cylinder, and had it rebuilt by a shop. Today we reinstalled the head, intake, timing belt, and everything neccesary to get it back together, and attempted to start it. Once again, it might start for a moment, then die and not restart. It also seems like it's still making a clattering sound, though not nearly as obvious as before. We can't seem to figure out why it won't start and stay running, and what the noise is. The timing keeps coming to mind, but I followed the timing instructions and tensioner adjustment procedure to the letter. I also checked for spark and fuel, and it seems to have plenty of both. Could the clatter be pinging/detonation, or possibly valves hitting the pistons? I've read that the 3.0 is an interference motor, and I've also read that it's not, I have no clue who to believe. When I turned the motor by hand, it turned very easily with no binding. Any ideas as to what's going on? My uncle's going broke commuting to work in his pickup.