My sister inherited a 1998 chevy 3500 with the 7.4L 454 Vortec from a family member fall of 2022. It'd been sitting for 3 plus years. BIL had done the usual stuff to get it drivable tires, new plugs, fuel filter, oil change, 3 cans of seafoam, and a new battery.
They have drove it maybe 300 miles in the last year without trouble. About 2 weeks ago they bought 2 medium sized cans of the R134 with the sealer and dye to try and seal the ac or to find the leak to get it working. It ran fine.
Yesterday they were going to drive it to eat, they dont drive it daily, but when they started it up it had the loudest ticking noise. They sent me a video and it was clacking pretty loud in video. They had a "mechanic" friend come listen to it and he said it sounded like a lifter.
They called the local shop cause they are scared to leave the house with it and they said the 454 was notorious for sticking lifters to put a bottle of ATF fluid in it and run it down the freeway for a 100 mile trip and that would help clear the gook sticking the lifter. Then change the oil again.
I AM NOT A MECHANIC so Ive come to ask if anyone here is a mechanic with advice?
Anyone with any experience with these engines?
It's clacking so loudly my sister is afraid to drive it period ( she thinks the engine will blow)
As always I come here for the collective wisdom and thank you for any insight