Good lifter gone bad?

[Michael]

Now that my engine runs again, I noticed that it makes a fairly regular sharp popping sound once every revolution. The sound tends to go away when the engine is under load, and is especially apparent at moderate rpm with the engine unloaded. Unplugging the #4 spark plug wire makes the sound completely disappear. Witht the engine running and the passenger valve cover removed, it appears that the #4 exhaust lifter is not pumping up - despite very healthy oil pressure. These are hydraulic lifters for a flat-tappet hydraulic cam (Comp Cams, X-treme energy 262 series). Lifters, springs, cam and timing chain were replaced as a set last summer - which is about 20 miles ago.

 

So, how does a good lifter go bad? Is the only recourse to pull the intake manifold, fish out the bad lifter, and replace it? Or is there a good chance that some other, more ominous engine problem caused the lifter to go bad?

[Modern Motorsports Ltd]

Is it a very loud 'popping'? Like an intake backfire or what?

 

Have you tried adjusting the lifter at all yet? I'd adjust the lifter first/check the pushrod 2nd, and test the valvespring last as well as a dial indicator to see your lobe isn't worn significantly.

 

Do adjust the lifter running if you can and do them all at the same time makes a nice improvement Anyone written up a live lifter adjustment here yet? If not a definite article this forum should have.