Mikeiser

Yeah my buddy had that same rumble under the same circumstances when the engine goes from v4 to v8 too quick. I got off the phone with Christian Brothers Auto to have a Jasper engine installed. They apparently had to talk to GM engineers sometimes and learned that their own engineers drive other brands because the 2015-2019 engines are quite the headache. Anyways, it'll run 9k to replace the motor.

I always went off the DIC. When I bought the truck I replaced everything but the brake and radiator fluid with Amsoil religiously. I have my suspicions the PO drove the truck like he stole it. Had the transmission replaced at 126k miles when the pump went to pieces inside of it.

I don't think that's a recommended practice anymore. I know Comp Cams and I think Crane Cams put out literature stating priming lifters could potentially over preload them, if that makes sense. What I ended up doing was removing the 2 fuses for the injectors and turned the engine over for 5 seconds at a time, a couple of times, to prime the oil system. Anyways, I ended up honing the lifter bore gently, cleaned it up with a rag dabbed in 10w30 and repeated 3 times till the bore was polished nicely. I test fitted the new lifter from AC Delco and it slipped in with a hair of resistance like the other non-dod lifters. 30 miles on it and no luck. I can hear ticking above 2k rpm still. I probably need to replace the cam at this point. Or buy a long block when I save the funds. A little history: AFM lifters replaced under PO(I don't have the printout of that, it'd be nice to see if it has any related info). 88k miles, bent pushrod, lifter replaced on cylinder 8 exhaust at dealership. 150k miles, lifter destroyed, pushrod replaced on cylinder 8 exhaust. 164k miles, lifter destroyed, pushrod replaced on cylinder 8 exhaust.

Same boat here. Halfway through my second time replacing exhaust lifter cylinder 8. Except my lifter both times were damaged. Cam was OK weird enough. Doesn't seem to be oil starved. My suspicion is the lifter bore is not perfect anymore, causing the lifter to hang and get obliterated by the cam lobe. I read somewhere an engine shop can insert brass repair sleeves but I'm not ready to remove the motor yet. Or maybe the cam lobe is worn just enough into an aggressive enough ramp profile to hurt the lifter. I noticed my second failure began after I passed a slow driver on a two lane road(aggressive acceleration). It's all speculation for me since I don't have the tools to measure the lifter bore and haven't found anyone else besides you experiencing this.