2012 Yukon 6.2 Engine Noise

[Dustin Jackson]

When I had a lifter failure everything looked great and I wasn't able to find any sign of a problem until I got the lifters out and then I found the problem. I was starting to get nervous up to that point.

 

[12XLYukon]

I went out and got a mechanics stethoscope and I’ve narrowed down where the noise is coming from I think. I can hear it best on the front of the oil pan and on a the block right where the head is bolted on on the driver side. It’s clearer on the block where it meets the head. I took a picture of where I had the stethoscope for everyone to see where I’m talking about.

 

[j91z28d1]

you could try cutting the oil filter open and looking for some metal from the cam lobe if it gets to that point. I don't think a stuck litter would show up, but next from stuck is usually cam lobe wear.

if you do, once cut open, wrap the element in pig mat for a few hours and it will suck all the oil out and leave the filter media clean to pull flat and see any metal specks.

 

[Doubeleive]

it doesn't sound that bad to me, I would try some cleaning and see if it clears up. if not it's not going to make any difference at this point.

 

[gooffeyguy]

I don't remember, but did you run the engine with the serpentine belt removed to eliminate any pulleys or accessory bearings

 

[iamdub]

I use 5w30 Mobil One synthetic with an ACDelco filter. Here are some pictures of the driver side. I didn’t stop to take pictures of the passenger but everything looked the same as far as color and buildup.

It could be cleaner, but I see nothing alarming for 212K miles. Unless it was more gunked up and your Mobil1 has cleaned it up a lot. I was wanting to see if there was any buildup that might suggest something broke loose and is clogging an oil passage in a lifter or sticking an AFM lifter. I'm not much a fan of diluting the oil or using harsh detergents in the oil. But, by the way it looks, I'd feel safe trying a light dose of a strong detergent, such as Berryman B-12 (#0116). If you do this, take note of you oil color before and after. Seafoam is the classic default, but Berryman is much stronger and cheaper. According to Berryman: "If you would like to try B-12 as an engine flush, simply pour into your cold crankcase approximately 1½-2 oz. of #0116 per quart of oil capacity. For instance, if your vehicle holds 6 quarts of oil, then you would use 9-12 oz. of or about two-thirds to three-quarters of one can. After you’ve added it to your cold oil, start the car and run it at idle 10-15 minutes until the oil is warmed up. Then change the spent oil and replace the oil filter."

I went out and got a mechanics stethoscope and I’ve narrowed down where the noise is coming from I think. I can hear it best on the front of the oil pan and on a the block right where the head is bolted on on the driver side. It’s clearer on the block where it meets the head. I took a picture of where I had the stethoscope for everyone to see where I’m talking about.

Well, cylinder #1 is an AFM cylinder, so that's still a lifter possibility. I know you just had it opened. But, if you find nothing else, you at least have it narrowed down to that general area. I say "general area" cuz sound can travel through a block, misleading you from the source. You could remove the rockers and pull the push rods to inspect. Could also us the push rods to "feel" the lifters.

But, first, have you checked the spark plugs, particularly the one in that cylinder? Perhaps it's just slightly loose.

 

[12XLYukon]

It could be cleaner, but I see nothing alarming for 212K miles. Unless it was more gunked up and your Mobil1 has cleaned it up a lot. I was wanting to see if there was any buildup that might suggest something broke loose and is clogging an oil passage in a lifter or sticking an AFM lifter. I'm not much a fan of diluting the oil or using harsh detergents in the oil. But, by the way it looks, I'd feel safe trying a light dose of a strong detergent, such as Berryman B-12 (#0116). If you do this, take note of you oil color before and after. Seafoam is the classic default, but Berryman is much stronger and cheaper. According to Berryman: "If you would like to try B-12 as an engine flush, simply pour into your cold crankcase approximately 1½-2 oz. of #0116 per quart of oil capacity. For instance, if your vehicle holds 6 quarts of oil, then you would use 9-12 oz. of or about two-thirds to three-quarters of one can. After you’ve added it to your cold oil, start the car and run it at idle 10-15 minutes until the oil is warmed up. Then change the spent oil and replace the oil filter."




Well, cylinder #1 is an AFM cylinder, so that's still a lifter possibility. I know you just had it opened. But, if you find nothing else, you at least have it narrowed down to that general area. I say "general area" cuz sound can travel through a block, misleading you from the source. You could remove the rockers and pull the push rods to inspect. Could also us the push rods to "feel" the lifters.

But, first, have you checked the spark plugs, particularly the one in that cylinder? Perhaps it's just slightly loose.

I pulled the spark plug from that cylinder today actually. It was in pretty tight.

 

[iamdub]

I pulled the spark plug from that cylinder today actually. It was in pretty tight.

Dammit. It just can't be easy, huh?!

 

[12XLYukon]

Dammit. It just can't be easy, huh?!

Also the AFM system isn’t active. I should have mentioned that. I noticed when I bought it that it stays in V8 mode all the time.

 

[Geotrash]

Having AFM turned off in a tune won't rule out lifter failure. Even non-AFM lifters will fail, as will AFM lifters - even if not switching between modes. But it does also raise the possibility that yours has had more than a tune done, possibly including aftermarket lifters and/or cam.

All I can offer are the steps I would take if I were in your shoes. I should mention that I'm a survivor of 2 cam and lifter failures on my 2012 XL Denali due to bad lifter trays received from a questionable supplier, installed by me during a cam swap. Many of the others advising you here have considerable valvetrain experience on these trucks.

What I would do next:
1/ Take the main accessory belt off and run the engine without it (briefly) to determine if the noise is still there. This will rule out the water pump, PS pump, alternator and tensioners on the accessory drive. Put the belt back on.

2/ Take the stethoscope to the rear of the drivers side cylinder head to rule out any exhaust leak from the (possibly) missing exhaust manifold bolt I mentioned earlier.

3/ Check all 4 spark plugs on the drivers side for tightness.

4/ Follow the procedure outlined in the service manual to safely remove the rocker arms, springs and pushrods on the driver's side without damaging the threads on the towers. You have to rotate the crankshaft in increments, starting with top dead center on cylinder #1 to make sure there is no pressure on the rocker arms as you move sequentially, or you risk stripping out the last 2-3 (aluminum) threads on each tower. Carefully lay them out on a clean towel on the workbench, in order. Inspect each spring for cracks, foreign objects or other damage. Roll the pushrods across a clean, flat surface to look for any bowing. Check the trunnion bearing on each rocker arm, looking for excessive radial or lateral play. A tiny amount is normal.

5/ If everything checks out, move on to the passenger side and repeat steps 3-4.

6/ If everything still checks out, then I would try the Berryman B12 + oil change suggested by Chris. You can also do this step before any of the others because it's easy.

7/ If still no joy, it will be time for the drivers side head to come off, followed by the lifters on that bank. Then the pax side head and lifters if still no joy. It's not a difficult job, but it is time consuming.