Has there been any progress on this? Mine has the exact same noise and curious if its a cracked header or not...
Sadly not yet. Still working on narrowing it down.Has there been any progress on this? Mine has the exact same noise and curious if its a cracked header or not...
The way the sound seems to be affected by the temperature of the engine, or the length of time the engine has been running, leads me to a few things:
Exhaust leak - specifically cracked exhaust manifold. The crack could become more evident as the metal heats up. But I can't see any tell-tale marks where exhaust could be leaking.
Lifter issue - Sound starts about 15-30 seconds after the engine starts up, so it could be related to the time it takes for the oil to get pumped up to the lifters/rocker arms, etc.
Piston slap - The shape of the piston/skirt could change as the metal heats up. I don't think it's this one because I visually inspected the pistons multiple times from underneath and I could not see any play at all, but that was when the engine was cold so I may be wrong.
And then there is still the pesky flex plate. It still could be a crack in the flex plate because the sound seems to come from the bell housing/back of the engine area.
So, sorry to say, I have not yet discovered the issue.
Keep us posted if you figure out what yours is. I will surely do the same.