Hey everyone,
I’ve got a 2013 Tahoe 5.3L with no misfire codes and no DTCs, but it’s making a horribly loud tapping noise from excessive rocker arm play. This noise just suddenly started. It was not a noise that gradual got louder. I initially suspected an AFM/DOD collapsed lifter, so I picked up a lifter release tool and pulled the valve covers and intake manifold.
Here’s what I found:
The intake rocker arm on cylinder #5 has noticeable slack, similar to what I’ve seen in AFM lifter failure videos.
However, this is a non-AFM lifter, which has me confused.
I rotated the engine manually with a ratchet, and the valve seems to open and close smoothly.
When the lifter unloads, it makes a popping sound, almost like it's sticking.
Looking for Insight
Has anyone seen a non-AFM lifter collapse like this before?
What’s the most likely cause of this issue? Could it be a weak lifter, oil pressure issue, or something worse?
What should I anticipate finding when I remove the head? I’m really hoping it’s not a damaged camshaft.
Any advice or insight would be greatly appreciated! Thanks in advance!
Take the rocker arm off and inspect bearing, pushrod for being straight and tip wear. If it all looks good, get a dial indicator on the pushrod. Rotate the engine manually and watch the indicator. If at any point you see the needle jumping or not moving smoothly it might be a flat spot on the roller. I know it's not what you want to hear but there's a good chance that's what's happening.