Got a 2007 Tahoe 5.3 that started this tapping/rattle noise. It started all of a sudden. It runs fine and it’s not missing and it hasn’t lost any power. I took the belt off because it sounded like a bad pulley but the noise continued with the belt removed. Not sure what it is. Motor has 260k on it and it just may be worn out. What do you guys think?
Even though the lifters were replaced 120K miles ago, the lifter(s) could be failing again. I wouldn't be the least bit surprised if it were an AFM lifter(s). In addition to the oil changes, did the dealer also perform the lifter and oil pump change? Did they replace them with the updated lifters? What about the VLOM?
It's not uncommon for an AFM lifter to get stuck in the collapsed position. This would cause a dead cylinder, though. The lifter could even have rotated in the bore. It'll still function, but it's roller and that cam lobe will get chewed up. If it is a lifter, it'll likely get worse. There's a chance it's not a lifter(s), though. A spun bearing often resembles a lifter tapping sound and it'll run just like always for a little while. Notice any change in the oil pressure? Do you have a mechanic's stethoscope?
To answer the title question- It's worth anywhere from scrap value to it's value as a core to whatever someone may value it as factoring in the documented history. 5.3s are a dime a dozen and one with 260K miles and possibly serious issues won't be very desirable.
