It has a little knock on start up, which is very common with the 8.1's. It fades off after a few seconds at idle. My brother has been in the car business for 40 years, says its a common issue and doesn't hurt anything
I had a 01 GMC 2500HD with a Vortec 6.0
cold start = knock knock knock
OIL STARVATION!!!!!!!!!!!!!!!!!!!!!!!!! I knew the sound right away.....its oil pressure problem
WHY? the friggin engine used a two piece oil pickup tube for the oil pump WITH an O ring in there.
Two piece oil pickup tube!!!!
I dropped the pan in the truck (4x4 so it was a pita) replace the O ring and the pan gasket = NO MORE TICK on cold starts.
The noise for me was cavitation.....just like having a hole in your straw
That engine lasted another 2 years before it threw a rod at 180K. When I got the truck at 150K it had bean BEAT TO CRAP as a carpet layer truck for many years...the oil cavitation noise had been there for ??? 80K miles or so I was told. On Cold starts in Colorado winters it was getting worse and worse, tick was lasting for 3-5 minutes now............I knew it was on borrowed time.
The cold start tick was indeed a oil pressure issue on that engine. I replaced exhaust studs, coil packs, and lots of other stuff chasing that tick
I also had a Ford V10 before my 7.3 = nice truck but I cannot afford the fuel! It was my shop truck and was used to haul rangers and explorers home. 2000 F250 V10 = 11.5 mpg no matter what! 7.3 (turbo diesel) is far superior but I also spent the last 8 years in the school of turbo diesel hard knocks!