Finally taking the Denali to the mechanic...I give

[Bullochdawg]

Ran transmission fluid through the engine. Took the valve covers off this weekend. Took the rockers off and cleaned the rods and everything I could get to.
Put it up on the rack to drop the pan. That's when I gave up. What a pain in the rear to try to get that thing off! Didn't even try it. Out of my wheelhouse. Plus, have had a bad cold since Friday. Did not feel up to trying to get all that stuff off.
Drained the oil and ran a little telescoping magnet in the drain hole. Got a little sludge out and a few small bits of metal flakes.
Friend said that could be normal for an engine with 152K on it. I'm not so sure.
Replaced the filter and oil.
That's it for my skill level!
Did notice that the oil pressure is at 40+ whether at idle or driving it down the road. Before, it would be around 20-25 at idle and then get up to 40 when driving. I had read this was 'normal'. Not so sure now.

Anyway, towing it to a mechanic that was recommended. Best case, it will be lifters. Worst case, I'm thinking rod bearings...aka replacing the engine.

Saw some videos where a bad injector caused the tapping. I'm not that lucky.

 

[PG01]

Good luck bud, hopefully you'll get some good news.

 

[Brian Wilson]

Could you explain the symptoms? A magnet will not pull out shavings from rod bearings. And gm says 10 psi oil per 1000 rpm. So only 6psi at idle is ok (600 rpm). While I don't agree, they seem to think it is fine. I only run 20 psi at 650 rpm idle when hot. I have no problems.

If you have a knock, I would at least rebuilt the top end. I think the GM piston slap BS is just an excuse for a ****** top end. If you have AFM, definitely change your lifters, because they are bad. Period. And if you had low oil pressure (due to a bad o ring or worn lifters or whatever, pay close attention to the area where the pushrods meet the rocker arms. Low oil will cause an irregular football shaped pattern on the pushrods. Which will grind the rods down and cause a knocking sound. Also, check the rollers in the lifters, best way is to use a magnetic base and a dial indicated on the lifter roller. Slowly rotate the roller. If the needle moves, it is bad. Replace it. Mine were all smooth to root but they were not true for whatever reason. I replaced my lifters, pushrods and a few rockers and I don't have 'piston slap' anymore.

 

[Bullochdawg]

Hey Brian, just got my Denali back from the mechanic. #4 lifter was bad. Had them change all passenger-side lifters. They inspected the cam and they said it looked good.
Also had them turn off the AFM. They said they do this mod more than anything else on these engines.

$1300 for new right-side lifters. Probably should've spent the money to do all, but....

$220 for AFM mod off.

$1615 total.

Have a 'normal' sounding engine again.

 

[TheAutumnWind]

Hey Brian, just got my Denali back from the mechanic. #4 lifter was bad. Had them change all passenger-side lifters. They inspected the cam and they said it looked good.
Also had them turn off the AFM. They said they do this mod more than anything else on these engines.

$1300 for new right-side lifters. Probably should've spent the money to do all, but....

$220 for AFM mod off.

$1615 total.

Have a 'normal' sounding engine again.

Thats great news! Could have been a whole lot more expensive.

 

[Bullochdawg]

Thats great news! Could have been a whole lot more expensive.

Yep. Guess the $7k engine replacement quote makes $1600 sound really good!!

I'm happy

 

[Brian Wilson]

I'm glad you got it running right again. However, I would think about a rebuild for next time. If you intend to keep the truck or engine for another few years at least. You still have AFM lifters, cam, and valley cover on the truck. Turned off in programming is great but you had a mechanical failure and you still have the mechanical components that failed. A complete DoD delete is not a scary as it sounds. And if another lifter fails, you will have access to every dod component so it will be a good time to change. All you need is intake gaskets, exhaust gaskets, head gaskets, head bolts (can't reuse the old ones) a valley cover, valve cover gaskets, lifters. And I would suggest a non dod/afm cam too but it seems like it's not essential. And changing the cam adds alot more money to the build. Just food for thought.

 

[08grey]

Hey Brian, just got my Denali back from the mechanic. #4 lifter was bad. Had them change all passenger-side lifters. They inspected the cam and they said it looked good.
Also had them turn off the AFM. They said they do this mod more than anything else on these engines.

$1300 for new right-side lifters. Probably should've spent the money to do all, but....

$220 for AFM mod off.

$1615 total.

Have a 'normal' sounding engine again.

What Denali has afm? I thought afm was only the 5.3 motor?

Sent from my SM-G930VL using Tapatalk

 

[Brian Wilson]

No. There were 2 different 6.2 in the denali starting in 2007. The first version did not have AFM or any AFM internals. The second version had AFM lifters, cam, and valley cover but did not have AFM turned on in the tune. The second version is the one to avoid or if you have it, install an AFM delete kit. So while you may not have AFM on your 2007+ 6.2, it is very likely you have AFM components which are extremely unreliable

 

[Brian Wilson]

The fastest way to check is with a flashlight and maybe a mirror. Check to see if you have a smooth valley cover under your intake. A smooth valley cover means you have the first version and don't have AFM crap in your engine.