I recently did a lifter job on my 5.3 @197000mi. the only issue before replacement was the infamous lifter tick. After replacing the lifters, and torqueing to specs in Haynes manual, upon start up still sounds like a small diesel engine, and the oil pressure has dropped to around 5-10. used to run at 35-40. I replaced the oil sending unit yesterday hoping that'd fix it but nothing has changed. I used ACDelco lifters. I didn't replace the push rods as they looked fine. I'm at a loss. I've taken the valve cover off at least 3 times now, and adjusted the rockers but cannot get it oil pressure up or the sound to stop. Next step is to do an oil change to see if there's any coolant in the oil from the repair.
Please help
Please help