Bad knock out of nowhere! Please help

[swathdiver]

It’s a little above 30 until you start driving then it goes up.

Ok, well that rules out a pickup tube or pump problem probably. Do you have something to use as stethoscope?

 

[wjburken]

He did. To my eyes, this is the first account we have of someone driving around for an extended period of time with 8 quarts and did not report any damage in doing so. Good to know!

Wow. It did not register with me that he had been running long term with 8qts. I mean the words were there but .....

That’s also the first I’ve heard of anyone doing that intentionally and not having issues.

 

[Basshead21]

Ok, well that rules out a pickup tube or pump problem probably. Do you have something to use as stethoscope?

No I don’t. I did notice drive at a Constant speed It sounded more like a spring rattling.

 

[swathdiver]

No I don’t. I did notice drive at a Constant speed It sounded more like a spring rattling.

Well, if you have a tool set, put some extensions together or use a long screwdriver, stick one end in your ear and the other to touch various places under the hood. You can run on over to your local Harbor Freight anf get this for four yankee dollars:

https://www.harborfreight.com/mechanics-stethoscope-63691.html

 

[pwtr02ss]

Wow. It did not register with me that he had been running long term with 8qts. I mean the words were there but .....

That’s also the first I’ve heard of anyone doing that intentionally and not having issues.

I put it off for over a year because I was afraid to do it (lifter rattle at start up), even though I witnessed it first hand on our shop truck. Like I said, I've put over 1k miles on it since doing it and 99% of those miles have been on the interstate. I'm not saying I recommend doing it but at the same time, it seems to have fixed the issue. I'm sure something else will break eventually (190k miles) and I'll fix it all at the same time (transmission failure, lifter failure, etc).

 

[Kraig]

As a side note, I can assure you the motor will run with 17+ quarts of oil in it—it will smoke like crazy, but it’ll run. I’d be willing to bet 8 quarts isn’t in danger of even getting close to the crank whilst running.

 

[kbuskill]

As a side note, I can assure you the motor will run with 17+ quarts of oil in it—it will smoke like crazy, but it’ll run.

Now you have our curiosity peaked so I'll bite....

How do you know???... lol

 

[Kraig]

Now you have our curiosity peaked so I'll bite....

How do you know???... lol

I bought a 4.8 Tahoe at auction. When I got it home, I pulled the dipstick and thought “nah... couldn’t be that full. The tube must be full of sludge or something.” Fired it up and there was LOTS of smoke. Then I drained the pan into my 5 quart pan. And again. And again. And some more... It smoked a lot less after that and then stopped and it’s still going at over 310k miles.

 

[Derick]

Check the torque converter too.

I was sick thinking I'd have to replace the 6.0. Turns out the Tc was crapped out. It sounded like hell too, all gears, and changed with revs. Easy enough to check out too with the inspection place coming off.

 

[iAmKendrickRay]

So My 09 Yukon just started knocking last week. I was hoping for lifters or something lesser but the more I'm reading, the less confidence I'm having. The knock is consistent with rpms and acceleration. Check Engine and Stabilitrak flash at 2500 rpms, then rough idles for about a minute or two. I've changed the oil and added Marvel Mystery. It's quieted the noise slightly, but I'm still concerned.

 

[wjburken]

So My 09 Yukon just started knocking last week. I was hoping for lifters or something lesser but the more I'm reading, the less confidence I'm having. The knock is consistent with rpms and acceleration. Check Engine and Stabilitrak flash at 2500 rpms, then rough idles for about a minute or two. I've changed the oil and added Marvel Mystery. It's quieted the noise slightly, but I'm still concerned.

Does your Yukon have the 5.3 or 6.2?
How many miles on your vehicle?
Have you been able to read the DTC codes with a scanner?
What did your oil look like when you changed it?

If you can post a video so we can hear the knocking, that might help folks here help you.

 

[iAmKendrickRay]

Does your Yukon have the 5.3 or 6.2?
How many miles on your vehicle?
Have you been able to read the DTC codes with a scanner?
What did your oil look like when you changed it?

If you can post a video so we can hear the knocking, that might help folks here help you.

5.3l v8
130k
I don't remember the exact readings but there were several.
The oil was super dark, didn't notice any sludge or metal.

I also noticed oil leaking near #7, but when we pulled the plug it was dry.

 

[wjburken]

5.3l v8
130k
I don't remember the exact readings but there were several.
The oil was super dark, didn't notice any sludge or metal.

I also noticed oil leaking near #7, but when we pulled the plug it was dry.

I would not rule out a lifter, or lifters, being collapsed. I believe your vehicle has AFM. Getting the codes would be helpful.

When you say oil is leaking near #7, what do you mean?

 

[iAmKendrickRay]

I would not rule out a lifter, or lifters, being collapsed. I believe your vehicle has AFM. Getting the codes would be helpful.

When you say oil is leaking near #7, what do you mean?

I'll post the codes tomorrow when I can run them again.
After I changed the oil and whipped away the residue, I started her up and I noticed leakage just below where #7 is but could not pin point exactly where it was coming from.

 

[wjburken]

I'll post the codes tomorrow when I can run them again.
After I changed the oil and whipped away the residue, I started her up and I noticed leakage just below where #7 is but could not pin point exactly where it was coming from.

Sounds good.

I noticed that it looks like you have a conversation on this topic going on two different threads. Might be good to keep both threads updated with your codes when you get them.

 

[iAmKendrickRay]

Sounds good.

I noticed that it looks like you have a conversation on this topic going on two different threads. Might be good to keep both threads updated with your codes when you get them.

I will... going to try and upload the video now.

 

[iAmKendrickRay]

Here's the video of the knocking with revs

 

[kbuskill]

Here's the video of the knocking with revs

Sounds too slow to be a rod knocking to me... sounds like half speed, so top end (cam, lifters, etc.)... IMO

 

[donjetman]

Sounds like its in the valve train to me too. Lifter, valve spring, rocker arm, push rod/

Not good

Don't drive it

Pull one valve cover at a time and look for the problem

 

[iAmKendrickRay]

Sounds like its in the valve train to me too. Lifter, valve spring, rocker arm, push rod/

Not good

Don't drive it

Pull one valve cover at a time and look for the problem

Unfortunately, we don't have a choice but to drive it. We're limping it when we do. Gratefully we don't have to go far.