I have just changed the timing belt on our 97 3.0 caravan and when I did the checks for timing mark alignments everything was good, so I put everthing back together and when I started the engine it started straight away,but there was a rattle on the back bank,I thought I had wrecked the engine so I pulled it down again,took all the spark plugs out and went through the proccess checking top dead centers and the vavles opening and closing,everthing is perfect no contact with the pistons,now I don,t want to put it back together with out finding out why it would rattle that way,any Ideas?