Yeah unfortunately it is, it depends on the severity of it. I found a few videos of engines that make little or no noise at idle but as soon as they're reved it comes out. but like I said try pulling the plug wire associated with the front two cylinders, one at a time of course. Even put the steathescope on the oil pan and see if its louder. You could only hear mine outside the car at 2500rpm when driving and above maybe 1200 when parked but on that part of the oil pan you could faintly hear it at idle. If you want to you can drop the oil pan and literlly grap each rod cap and see if there is play in it. Unfortunately that noise sounds exactly like what I have and just like what rod knock is. I guess we'll have to see how this comes out. I hope we both just have oddly defective water pumps
. Remember that in an engine the crank can carry sound from one side to another. When I first heard my noise I thought it was an idler pulley or something on that end too cause it was so loud but from under it it sounds like the furthest cylinder from it! Check it out, lemme know what you come up with.