2007 chevy 2500 6.0 tick/knock problem

[coletrain777]

Hey all, new member here looking for some advice.
I recently received a call from a customer that his 07 Chevy with a 6.0 had an oil pump failure. He said he stopped at a gas station and as he was slowing down the truck lost all oil pressure. I went and towed the truck back to my shop. I replaced the oil pump for him and all was well for around 3k miles.

He called the other day and said his motor had developed a loud tick or knock suddenly. I went and checked it out and sure enough it has what sounds like extreme lifter noise that doesn't go away or reduce and only gets louder with increased RPM's. The other odd thing i noticed is that the oil pressure gauge fluctuates around 10 or so lbs back and forth when at cruising rpm (from 40 psi up to around 50, and then possibly down to 35) this continues the entire time. This leads me to believe he possibly may need a set of main bearings/ turned crank???

He has a very well maintained engine/truck and he would like to keep his current engine if possible. Just looking for ideas as to what you would look at first as the possible issue. I will pull the engine tomorrow and take a look.

[Cutlass]

This could be two separate issues.
The oil pressure senders are a common failure which could cause your pressure fluctuations.
The lifter tick could be a lifter that failed or spun sideways in its plastic retainer tray. The fix is new cam, lifters, and retainer trays.

[Cutlass]

Occasionally valve springs break, too. So you'll need to narrow it down exactly which valve train component failed.