Thedortondad

Have you taken the valve cover off to check if the valves are moving the rocker arms?

I turned it over with the valve cover off and the rocker arms were moving for cylinder 6. Does that rule out the collapsed lifter diagnosis? I originally pulled the valve cover to check and see if a valve spring was broken, but they all looked to be intact and undamaged. Would a burnt valve cause these issues, and still allow the valve to move up and down, showing the rocker arms still functioning as normal? Used the “rag test” on the exhaust last night and it acts like it wants to suck the rag up into the muffler. Thanks for the replies.

I didn’t plan on posting, but searched for about 30 mins to find answers to my questions without being able to find them. I recently bought a 2011 Suburban with 135k miles. Ran fine for about 3 weeks, and one morning my wife went to start the truck and it had a god awful miss. I changed plugs and wires, as I assumed they had probably only been changed once and could use a new set anyway, which seemed to make it run a little better, but still has a miss. Tracked down the miss to cylinder #6, changed the coil, and nothing changed. Checked the compression and it has absolutely none. Checked cylinder #4 for compression and it’s fine. Pulled the valve cover off and checked to make sure all rockers were moving while trying to start it. At this point, I’m trying to put it in TDC to blow air into the plug hole and see if it’s a piston/ring issue or valve issue. What are the indicators on this 5.3 for TDC? Really just trying to narrow it down to what it might be and what my next move for it will be. Any help/suggestions is greatly appreciated. Alex