What I do know is that after the 1st water pump was installed it was as quiet as a new engine. After p.o.s. new pump was replaced again, is when the clattering started. The idiot light is going out so, I can only assume (we all know about that) that it is at normal pressure. And, if I look in the oil fill hole I can see some fresh oil in that neighborhood. All I am sure I can hear is lifters. Any further thoughts. And, checking the chain tensioner will involve pulling at least the right side valve cover correct? If it isn't full of oil, suspicion would fall to the oil pump pick up correct? I just want to get this thing done and over with. Give me a 3.5 any time!