My Chevrolet Tahoe has an engine clicking noise
2004 Tahoe, 260,000 miles. Just recently engine started making clicking
noise. Auto Shop removed valve covers and says its "lifts and crankshaft".
Also, said engine full of sludge. Any perspective on the diagnosis and what
questions to ask would be appreciated. Quoting bill of $4,200 to fix. Car not
worth that much.
Sludge is never a good sign, and lifters will start to tick in a sludged up engine, but noise from a crankshaft is far worse, means you have a possible bad main bearing. At 260K miles, that engine is done. You can probably get a replacement engine cheaper than rebuilding it, but as you note, car is not worth that much. I'd sell it off for parts of as a mechanic special.
any motor with that kind of mileage is going to be worn , plus the oil wasn't maintained , so shy of a new motor there's no mechanic in a can that'll fix it . Change the oil and hope for the best .
I would either scrap the car or install a rebuilt engine.