Must not be too many long term hemi owners here. It sounds like the dreaded Hemi Tick. Google that term... Essentially, although a fantastic engine it has a design flaw. On my 2015, I had one side "fixed" twice with bolts being replaced. The last fix at like 70K miles was on both sides with a new manifold on one. Many dealers have an almost exclusive tech who works on these. My 2015 had a 100K power train warranty. As of 2016 I believe, they went to 60K. Speculation is that the "hemi tick" was part of the reason... Like I said, google the term and you will find many resources explaining in detail what it is all about. I was hoping they had fixed it by now...but apparently not. There are a couple of permanent fixes, but they cost so, Ram must have done a cost analysis and determined they would just go with the existing...problem... Oh, my last fix seemed to work... AND, it doesn't happen on all of them..just quite a few... All covered by warranty. BUT, if you hear it be sure and get to the dealer BEFORE 60K... Seriously... You will find it is like a no big deal at the dealerships. They are used to it...and don't even argue with you. They look up your VIN and your mileage and