If a valve lifter collapses or otherwise fails in a DOHC 4 cylinder, does that pretty much mean a whole top-end rebuild, or can you maybe get away with a relatively simple tappet replacement? Would a camshaft have to come off no matter what?
Do you mean it came apart, resulting in pieces falling into the valve area, and the cam lobe getting scored?
There’s a number of ways this could go. The simplest would be to replace the bucket. It’s also quite possible the cam lobe could be damaged; all depending upon how the bucket failed.
The more serious version would be if the cylinder head bucket bore or if the valve stem was damaged or mushroomed badly. That would necessitate cylinder head removal and repair or replacement.
What needs to be known is the type of failure or a few clear pics.
Thank you both for the replies. I’m speculating prematurely. My daughter’s car is making an intermittent racket that I suspect is a valve lifter, and I was just fishing for thoughts. I suppose the smart thing to do would be to take the valve cover off and have a look, before something awful happens. Thing is, the (loud) rattle is so infrequent and fleeting that I wonder if anything is likely to be noticeable under there yet.
Hard to believe that a bucket is coming apart, then. Maybe the variable valve timing gizmo? (total guess)