Another engine tick/knock/slap concern...

[Meathead16]

I know this topic has been asked about and mentioned as many times as how many of these engines were made and I've searched and read up on many things to look at and check out. For awhile now there's been a raucous under the hood on cold startups but I assumed it was either piston slap or something was up with the timing chain or tensioner. Engine has ~250k miles but I've heard timing chain component issues are rare with these engines and it went away quick enough where I didn't consider it a pressing matter but yesterday I was stopped at a red light and heard the same tick/slap noise but it was loud. I actually thought it was the car next to me until I realized I kept hearing it every time I'd pass another car. The noise matched RPM, and sounded sharp like a coil arching but had that deepness to it akin to rod knock. Got to where I was going, shut the truck off, restarted it after 15 minutes and noise was still there, and LOUD. With the hood open it sounded like I was hammering a punch against the engine.

I took a quick video of the noise. By this time truck had sat for ~12+ hours and when I started it the noise lasted for a few seconds on start up and then faded away like it usually does. Still sounded more pronounced than usual but nothing like earlier.

My main concern and confusion is how the noise wasn't there when I started my trip. I didn't notice it until after ~15 minutes of highway driving. It's always been only on cold starts, never randomly starting while driving. Then to go away again. Or at least back to normal. I thought intermittent was for electrical. When hard parts wear or break, they're broken, nothing intermittent about it. For how intense the noise was just to calm back down hours later has thrown me through a loop.

The second part of the video is of the passenger side of the engine that sounds like a diesel. It has sounded like this for as long as I can remember and I've had the truck about 3 years. It's only on bank 2 though, bank 1 just sounds like an ever-evasive vacuum leak, but from what I've seen/heard, almost all of these engines sound that way.

Thanks in advance for any insight you can offer.

 

[Meathead16]

Bump?

 

[Matthew Jeschke]

I don't hear anything that stood out to me in your recording?

...

I went through my engine at approx. 230k miles with what I'd call a super flush. I poured an entire can of seafoam in the crank case and let it idle for 1 hour. Then I pulled the valve covers and poured Berryman B12 Chemtool (down the pushrods) onto the lifters (so the lifter cups filled up). A couple days later (no driving in interim) I changed the oil. It eliminated my obnoxious lifter tick.

I think these engines are somewhat prone to spinning lifters / burning out the cam at high miles. Not sure if that's what you're experiencing but I've had two personal friends who had that happen. When you remove the valve covers check pushrods for play. You'll need a breaker bar to manually spin crank so each valve to the heal of the cam. Also check if you've thrown any of the rocker arm needle bearings (are any of the bearing caps loose or missing?)

How do your motor mounts look... does engine rock / shift in the engine bay? How about the transmission mount? CV Joints?

Does engine run smooth?

How is the power?

Sounds like when it warms up the symptom / noise doesn't go away?

 

[B-train]

I hear some lifters that lost prime. How often do you change the oil? What type of oil?

If it were mine, I'd dump in 1/2 quart of Dexron 3 in the oil and take it for a nice long drive. Drop the oil immediately when back home and refill with a good quality 5w-30.