Ticking/tap sound can’t figure it out!

[Foriogmc]

Alright I have a Sierra 1500 6.0 with afm. We had a failed lifter in cylinder 6 with a bent push rod we did a top end repair with the following parts replaced: 

all new melling lifters 

melling pushrods 

new lifter guides 

new oem camshaft

new oem spark plugs and wires 

new oil pressure sensor 

new valley cover 

Truck runs great and goes into 8 and 4 cylinder mode fine but I get a random tap sound coming from the passenger top end. The weird thing is it comes and goes. 
 

I’m lost as we pretty much replaced everything top end wise and done think this is a Normal valve tap/click as they are new and seems to be louder then just a click. 
 

i went to a dealership thinking I should just get rid of the rig before she blows again, funny thing was the salesman said you thinking of trading this in because of that tapping noise! I didn’t tell him about that hahaha. 
 

love the truck but I’m lost of what to look for or fix next. 
 

any suggestions or help would be appreciated. 
 

Happy 4th! 

 

[Mike GMC]

It might be a long shot, but check your torque converter to flex plate bolts and see if they are tight.  Pull the starter and roll the engine with a wrench in the crank bolt until you can see each one in the starter hole.  If they are loose, pull each one and use some red loctite on them and tighten them back.

 

If that's not it, did you torque the rockers down using the recommended pattern and rolling the engine over?  If not, retorque them and see if that helps.

[Screan29]

A chevy without ticking? I had a suburban do the same thing. After we rebuilt the top end and did away with the hydraulic lifters it all but went away. It is probably always there but when the truck goes from v8 to v4 and back to v8 it may be more noticable with the hydraulic lifters build back up. AFM destroys engines. It's why Cadillac did away with it when they tried it in the 80's. One of the first things I do is deactivate it on all of my chevys. I rather loose a little mpg then destroy my engines. 

 

Good luck! 

[2019 Red]

My 2010 Silverado had the "ticking" noise but only while traveling at 65 mph or above, it did it for several years and no one could give me an answer. then while getting an oil change the dip stick tube broke off and came out with the stick. the service man told me this was a KNOWN issue with a TSB from GM and I should get a repair for free.

  He was ALMOST right, faulty dip stick tubes were a known issue and will begin to weaken and TAP the firewall. But repairs are only free if your truck/SUV has less than 60K miles.