collapsed lifter with rocker arm still moving?

[tig488]

2014 sierra 5.3L with 127000 miles,

 

started having a very light barely audible tick a year ago.  started getting CEL bank 2 A/F ratio imbalance.  removed valve cover and noticed cylinder 8 intake rocker arm has about 3/8 inch of play between rocker and pushrod.  removed it hoping the pushrod was broke or bent but was fine.   cranked it and the rocker arm moves even with that much play.  is that possible? and cylinder 8 isn't an afm cylinder.  

[tig488]

update.  shop tore it down.  intake lifter cylinder 8 (non DOD) exploded sending shrapnel into the engine.  that was the tick that started a year ago and got worse all of a sudden when it broke apart. camshaft bearings all messed up.  having new ones put in tomorrow.  i had already purchased LS7 non DOD lifters, stock non DOD camshaft, and everything else needed to do DOD delete.  had also purchased a new oil pump since we were tearing it down because i got a few P06DD codes, as well as replacing timing chain and tensioner, removing vacuum pump, and replacing the torque converter with a Florida TC.  hopefully it'll run another 125K miles. 

[JONBLARC7]

I would think about a new radiator and oil cooler lines.  The radiator has the oil cooler built into it.  I replaced mine when I lost two rod bearings.

[tig488]

update, got the truck back runs great. quiet again.  one issue,  my oil pressure is on the high side so he ran a diagnostic and its showing a po6DA.  I was getting a po6DD before that's why I replaced the oil pump and solenoid.  this code means the solenoid is stuck open causing pressure to be high.  by my gauge it shows around 50-60 but his reader shows it spikes up to 70-80 under heavy throttle.  we think it might be a wire issue because the code shows up on his scanner with the key on without it running, but my truck doesn't show a CEL.