Hi. I have a 2013 Dodge Grand Caravan with 210,000 km on it. I had a whine near belt so I replaced the serpentine belt and the tensioner pulley. A month later I know have a major rattle/ knock coming from top back of engine when in idle. It goes away as soon as rpms go up past 900 or so. The engine has the same power and nothing else seems to be a problem. Air conditioner is good and no leaks to be seen. One thing I did notice is that it is very hot right now and I don’t see water below the van from the ac like I normally do. Not sure if relevant at all.