I must defer to the guys who know this stuff, but my car makes a rattle in the engine area when it first cranks up cold. I suspect that the oil pressure does not build up for a few seconds and therefore the pressure fed tensioner system does not tighten the loose timing chain. As to the cause of my rattle (loose chains?)I will not know until Saturday's investigatory activities reveal more, but I do understand that when the car cranks, it immediately develops oil pressure which feeds the pressure fed tensioners which tightens the chains and the noise, of course, then disappears. I further understand that check chain tension while the car is anything less than "overnight" cold will not reveal much as the pressure fed system does retain pressure when you turn off the car for some period of time. The Chains will not rattle on restart unless the engine has cooled and had sufficient time for the system to loose pressure.
I'll update after Saturdays education.