2009 6.2L Engine knocking.

Shaun Toole · May 24, 2023

My apologies for the selection on year but I’m hoping someone has experienced the noise I’m hearing. I bought a 2009 Yukon Denali with the 6.2L and it has a knock that seems harmonic with cylinder 6 and also audible through the water pump. When the rpm’s are increased above idle it sounds like marbles in a can. The only code (and no light) is a p0011. Engine oil pressure at idle is just below 20 and at 25 when rpm’s are brought up (seems low).

Immediately after purchase I have done the following;

1. Oil change with sea foam detergent.

2. Oil pressure sensor.

3. Full swap and inspection of lifters. There was no obvious damage.

4. Cleaned push rods.

5. New plugs and wires.

5.b Changed oil again after 10 minutes of idle.

6. Clean and inspect Oil timing valve.

7. Replace VVT solenoid.

8. Replace Camshaft positioning sensor.

The engine idles well at 550 but knocks loudly. At any increase it sounds like marbles. Any thoughts on what I should be looking for?

CamGTP · May 24, 2023

If all you get is 25psi of oil pressure at like 1500-2000+ rpm I'd say something in the lower end is going bad. With the knocking sound you hear it could be a bad bearing.

Without me there in person to hear the sound, it's tough to guess at it.

swathdiver · May 25, 2023

Yeah, can you take a video, post to youtube and link it here?

Marbles is usually a bad cat or a heavy marbles sound is the flex plate or torque converter bolts.

Now you said that you installed new lifters or moved them from one side of the engine to the other?

What brand, weight and amount of oil have you been using? Which oil filter? These are questions for the post-mortem.

elcamino · May 25, 2023

Quote

1. Oil change with sea foam detergent.

Snake oil.

Shaun Toole · May 26, 2023

Here’s a video of the knock.

A couple of updates since the post. All check engine lights are clear, the OBD code is p0011. Just incase it was advanced, I checked resistance and output of the knock sensors and replaced them.

The oil pressure has increased at idle to ~32-35 at cold start. The flush oil and the current new oil is Castrol Full synthetic with a STP filter 5w30.

All of the lifters are new, all of the push rods cleaned straight, all of the rockers and springs appeared to be in good condition.

newdude · May 26, 2023

That sounds like a broken valve spring or a shot cam.

Or its a rod about ready to depart the block.

Either way, time to open it up.

Shaun Toole · May 26, 2023

On 5/25/2023 at 12:40 PM, elcamino said:

Snake oil.

What is snake oil? I’m am certain all of the issues when I bought it were tied to poor maintenance with the oil.

Shaun Toole · May 26, 2023

59 minutes ago, newdude said:

That sounds like a broken valve spring or a shot cam.

Or its a rod about ready to depart the block.

Either way, time to open it up.

Then that is what I shall do! Is it possible to get to the rod bearings without pulling the engine? Or is it best to do a full exploratory inspection?

CamGTP · May 27, 2023

You can remove the front diff and the front crossmember under the oil pan, then remove the oil pan to check all the rod bearings.

newdude · May 27, 2023

16 hours ago, Shaun Toole said:

What is snake oil? I’m am certain all of the issues when I bought it were tied to poor maintenance with the oil.

Products in a can or bottle that "claim to fix" certain problems. STP, Motor Honey, Bars Leak, etc.

Olden day term that's still used today for sleazy con salesman back in the day who went around selling elixirs that would cure all sorts of ailments and diseases.

Edited May 27, 2023 by newdude

KARNUT · May 27, 2023

7 minutes ago, newdude said:

Products in a can or bottle that "claim to fix" certain problems. STP, Motor Honey, Bars Leak, etc.

Olden day term that's still used today for sleazy con salesman back in the day who went around selling elixirs that would cure all sorts of ailments and diseases.

I’ve used all those products. I’ve used stp in heavy equipment gear boxes. As far as bars leak it’s keeping me from having to fix cracks in my heads going past a year now. A common problem in some 5.3s. On the road bars leak has gotten me home. I had an experience drag racing against my brothers little red express truck years ago at raceway park in Baytown TX. I was driving a 69 GTS dart with a 340. Shifting into 4th edging my brother at the line I heard it knocking. Two cans of STP went in and I drove 70 miles home. I gently drove it on Saturdays for 6 months around the block until I got bored and sold it. Did STP help? I wouldn’t bet against it.

Grumpy Bear · May 27, 2023

GM sells a motor flush and a top end soak to free rings. They also sell a radiator pellet to seal leaks. Similar products to Bars leak, KREEN and GUNK Motor Flush. Crutches if you will.

Then we have products that actually cure issues. Red Line MTL was developed to cure the lack of a useful first gear synchromesh in 80/90's Honda 5 speed manual gearboxes. A transmission with a synchromesh first that would not go into low gear above 2-3 mph would do so from any speed you felt comfortable shifting into. Handy in a gymkhana event or winding mountain road. Rain-X original..... Cerakote..... Red Line Shockproof Heavy....... HPL SAE30/40 EC....... All products that fix things....and do it well. Techron and product like it. Red Line S-1, AMSOIL P.I.

Then we have some real losers. Z-Max and Slick 50 come to mind. It's not that they don't work. It's that they don't work for long and in the case of the chlorinated solvent, can cause damage. Snake oil.

Snake oil makes claims it cannot produce or produce for as long as stated.

Edited May 27, 2023 by Grumpy Bear

diyer2 · May 27, 2023

What you need is a whim wham for a water wheel.

Grumpy Bear · May 27, 2023

2 hours ago, diyer2 said:

What you need is a whim wham for a water wheel.

Na, a bucket of steam will fix it.

swathdiver · May 27, 2023

On 5/26/2023 at 3:22 PM, Shaun Toole said:

Here’s a video of the knock.

That's not normal nor normal here. Shut it down and start by taking off the rocker covers and inspecting the valve train for bend pushrods, broken springs, etc. I have a bad feeling that the problem lies deeper though, like a connecting rod or piston.

Fellas, should he do a compression test first? Inspect the plugs first and do a compression test.