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.

 

[Meathead16]

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?

Power has been lacking.. not necessarily sluggish, but she has seemed more tired lately. Could be smoother, I've been chasing down some high fuel trims and I think my intake manifold has a vacuum leak. Waiting on metal carrier gaskets to swap out. Changed out transmission mount while back and just finished the engine mounts recently. Engine movement is minimal. CV joints are... there? lol how would I check those? When removed from the truck they move freely and quietly with no sticking or binding. I've changed out the valley pan gasket and the cam lobes did exhibit some wear. Though interestingly, my last UOA came back showing very little engine wear. Though silicon was a little elevated.

The noise is best compared, at least as I hear it, to piston slap. The engine sounds noisy on cold starts and quiets down within 3-5 seconds. The piston slap noise sometimes only lasts for 1-2 seconds. What happened is I left for work in the morning, usual second or two of noise and then quiet. It's about a 12 mile, 15 minute drive on the highway to work. On the exit ramp I heard the same piston slap type noise from the engine but now it was constant. It matched RPMs, and sounded like either the biggest exhaust leak ever or a rod knock. It made the noise in step with engine speed for the remaining ~4 miles of city driving. I shut the engine off, it sat maybe half an hour and I restarted it and noise was still constant matching engine speed. After the engine sat for ~15 hours, I started it and the noise lasted a few seconds and then quiet again. Drove it home without issue.

Maybe a week later same thing happened. 2 - 3 seconds of noise on cold start up, quiet, jump on the highway, during the last mile or so of highway I hear the noise constant again. Noise occurs until I get to work. Engine sits, driving it home, I forget if the noise is present or not on the drive home, but by the next morning for sure the noise is gone and all normal again.

As of now, this issue has yet to resurface. Start up still sounds like a timing chain just flopping around and the piston slap noise occurs for a second or two and then quiet. I heard the timing components on these engines are pretty solid and usually last the life of the engine. Is that true?

I'll pop the valve covers off.. I'm pretty sure gaskets need replacing anyway even though I just did them a couple years ago. Last time covers were off everything seemed tight, but it's worth a look.

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.

What do you mean by lost prime? Should the lifters retain oil when the engine is off and by losing prime they have lost that oil reserve?

I change my oil every 3000 miles, full synthetic 5w-30, usually Mobil1, sometimes Penzoil Ultra Plat., and on occasion Valvoline Advanced. Mobil1 Extended performance or AcDelco for the filter.

I've heard about putting atf in the crankcase but had reservations about the possibility of something breaking free and clogging up an oil passage

 

[Marky Dissod]

... I change my oil every 3000 miles, full synthetic 5w30, usually Mobil1, sometimes Penzoil Ultra Plat., and on occasion Valvoline Advanced. Mobil1 Extended performance or AcDelco for the filter.
I've heard about putting atf in the crankcase but had reservations about the possibility of something breaking free and clogging up an oil passage.

If you want a slower but eventually equally effective idea, use Valvoline Restore & Protect 5W30. After two oil changes my mechanic asked me if I bought a new dipstick; I have not. It works, it just works SLOWLY, so you don't need to worry about thrombolytic clots playing hide and seek in your engine's labyrinth of oil passages.

As for ACDelco oil filters, next time, lie to your parts person and say you have an LQ4 engine so you can get the longer oil filter.
If you're changing it every 3000 miles, I'll just say about oil filters, avoid ACDelco filters whose part numbers end in 'E', as in:
Avoid PF61E, use PF61 or UPF61.

In hydraulic lifters, some of the oil that pumps them up eventually does drain out; yes they lose some prime.
That is the biggest reason why I wait at least 1min after starting the engine before moving the shifter out of 'Park'.
2nd biggest reason: after sitting around for more than a few hours, my engine does a wee lil bit of cold piston whap and lifter click for the first 20seconds.
(Once made an exception driving Mom to hospital. Despite her condition, she reminded me to start up the engine in advance next time.)