05 Envoy lifter issues

[richard2717]

My wife drives an 05 GMC Envoy Denali with the 5.3 engine. Roughly 145k miles on clock. It is apparently the 1st year of dod afm. She has been complaining of a loud tapping coming from the engine occasionally. When it is tapping it is down on power as well. When not tapping runs fine.

Reading up on it it says half the lifters have springs on the bottom of them for the afm and over time get stuck. I am deaf so I don't hear it obviously but she says it is getting to be more often now. I just changed the oil the other day and half expected to see metal in the old oil, but there was none that I could see.

I had a local shop look at it and the only offer they had was a new Jasper reman to the tune of 12K installed. Not happening. They would not even entertain opening the motor. Still driving the car 300 miles per week at this time.

I guess my question is would new lifters be an ok choice if I decide to fix and would it require changing the cam as well or could new lifters be used on the existing cam? I have no experience with the ls platform. This thing is AWD so I would rather do it in frame vs pulling the motor.

What would you do, fix the engine or get another vehicle for her? Car is in great shape other than this. Just replaced front hubs & axle shafts a month ago.

Thanks
Richard

[geezer#99]

I looked into that afm system a couple years ago on the wife’s 07 Tahoe.
Big chunk of change just to replace lifters. Seems top end of motor needs to be removed. I was quoted at least a couple grand.
You can get module replacements for a hundred bucks instead.
Have you looked into these?

https://www.amazon.ca/AFM-Silverado-...0&gad_source=1

[richard2717]

that looks interesting. For the price it is worth a shot and can keep it around if the motor is too far gone for it to help now. Thanks for the link.

[richard2717]

should be here tomorrow. I did not realize the heads have to come off in order to change lifters in the LS platform. I assumed it was like gen I and just pulling the intake.

[geezer#99]

Hope it works for you.
At least you’re only out less than a sawbuck if it doesn’t.

[richard2717]

Originally Posted by geezer#99

Hope it works for you.
At least you’re only out less than a sawbuck if it doesn’t.

That's for sure. Its way better than throwing a couple thousand blind.

I talked with my son down in FL this morning and come to find out he had one on his 2015 sierra with the 5.3 until he traded in for a Duramax dually. He said killing the AFM did not make any measurable difference in his fuel mileage.

I will report back in as soon as I see if it makes a difference.

Richard

[leegreen]

I'm not an expert on DOD, but I did read up on how to delete it in consideration for using a DOD era engine in a swap. I suggest reading up on what that device does with regards to the lifter oil management solenoid and the PWM torque converter before running it long term or you could be looking at other problems down the road.

Since your noise is intermittent, can probably rule out rockers and wiped out lifter/cam lobe. Those should also show up inside your oil filter, did you cut one open?

What does your oil pressure do when the clacking is heard?
If it drops there may be pressure regulator issue, if pressure is constant there might be air in oil via failing pickup tube o ring which may only show up when oil is hot. Overfilling with oil to the point that o-ring is submerged is a test, but you don't want to drive it that way, so if your noise is intermittent that is not much help

Do you know the history of oil changes?
Gunky engines more prone to AFM lifter failure. At 145k miles your engine should be at midlife unless it has been abused.

Heads need to come off to do lifters, if you are doing lifters you might as well do DOD delete, but you need to do cam as well. Doing cam with radiator and in may or may not be possible, depends how hard on things you are willing to be. Once the timing cover is off the oil pump is right there, but the bolt for pickup tube is hard to get to and you don't want to drop it in the pan. By this point you are looking at a short block in a stripped engine bay and pulling the engine is not that much work.

[LS short box]

A few more things to consider.
1. New head bolts if you pull the heads since they are TTY.
2. If you try unbolt the exhaust manifolds from the heads there is a better than even chance some will bolts will snap off in the cylinder head.
3. If you go forward no Ebay or Amazon parts.
4. GM lifters and lifter sleeves only.
5. Drain the oil and see if there is any "glitter" which means metal has been spread thru the engine. Really not good. That is the first thing I would do.
6. R&R the cam/oil pump and timing chain. Make sure you get the correct o-ring for the pump.
You need to center the oil pump gear. Cheap plastic tools are available.
7. I could be wrong but I don't believe you can get the cam out without R&R the following:
Rad. AC condenser. Maybe the grille?
Don't know what have for shop but this project would be no fun from ground level.
Sorry to be such a Debby Downer.
Good luck.

[3drburb]

About 5 or 6 years I turned on my Chevy Express work van with a 4.3 only to hear a very loud clanking sound like my lifters had come apart in the engine, so I quickly shut it down and was really worried that it was time to replace it with my spare engine.

DISCLAIMER!!! LOL
After some of research I decided to dump a full can Gumout in the engine oil and let it run.
After a few minutes it was back to normal and quiet, so I let it run for about 7-10 minutes and did a hot oil flush with a new filter then drove the van for a day and did another oil flush and new oil filter.
I am still driving that van and I pour a little Gumout in my oil before an oil change.

It worked for me, but I did it as soon as I heard the noise.
I just wanted to let you know what I did. Disclaimer!!

[richard2717]

Originally Posted by geezer#99

Hope it works for you.
At least you’re only out less than a sawbuck if it doesn’t.

Amazon dropped it off this morning and I put it in before she left for work.
She messaged me when she got to work that car was running a lot better but about 5 miles before arriving at work the lifter tapping was back although it still ran good.

Originally Posted by leegreen

I'm not an expert on DOD, but I did read up on how to delete it in consideration for using a DOD era engine in a swap. I suggest reading up on what that device does with regards to the lifter oil management solenoid and the PWM torque converter before running it long term or you could be looking at other problems down the road.

Since your noise is intermittent, can probably rule out rockers and wiped out lifter/cam lobe. Those should also show up inside your oil filter, did you cut one open?

What does your oil pressure do when the clacking is heard?
If it drops there may be pressure regulator issue, if pressure is constant there might be air in oil via failing pickup tube o ring which may only show up when oil is hot. Overfilling with oil to the point that o-ring is submerged is a test, but you don't want to drive it that way, so if your noise is intermittent that is not much help

Do you know the history of oil changes?
Gunky engines more prone to AFM lifter failure. At 145k miles your engine should be at midlife unless it has been abused.

Heads need to come off to do lifters, if you are doing lifters you might as well do DOD delete, but you need to do cam as well. Doing cam with radiator and in may or may not be possible, depends how hard on things you are willing to be. Once the timing cover is off the oil pump is right there, but the bolt for pickup tube is hard to get to and you don't want to drop it in the pan. By this point you are looking at a short block in a stripped engine bay and pulling the engine is not that much work.

Originally Posted by LS short box

A few more things to consider.
1. New head bolts if you pull the heads since they are TTY.
2. If you try unbolt the exhaust manifolds from the heads there is a better than even chance some will bolts will snap off in the cylinder head.
3. If you go forward no Ebay or Amazon parts.
4. GM lifters and lifter sleeves only.
5. Drain the oil and see if there is any "glitter" which means metal has been spread thru the engine. Really not good. That is the first thing I would do.
6. R&R the cam/oil pump and timing chain. Make sure you get the correct o-ring for the pump.
You need to center the oil pump gear. Cheap plastic tools are available.
7. I could be wrong but I don't believe you can get the cam out without R&R the following:
Rad. AC condenser. Maybe the grille?
Don't know what have for shop but this project would be no fun from ground level.
Sorry to be such a Debby Downer.
Good luck.

If I get to the point of rebuild it will be because I finally found her something else for sure but it would give me an opportunity to dig into one of these motors.

Originally Posted by 3drburb

About 5 or 6 years I turned on my Chevy Express work van with a 4.3 only to hear a very loud clanking sound like my lifters had come apart in the engine, so I quickly shut it down and was really worried that it was time to replace it with my spare engine.

DISCLAIMER!!! LOL
After some of research I decided to dump a full can Gumout in the engine oil and let it run.
After a few minutes it was back to normal and quiet, so I let it run for about 7-10 minutes and did a hot oil flush with a new filter then drove the van for a day and did another oil flush and new oil filter.
I am still driving that van and I pour a little Gumout in my oil before an oil change.

It worked for me, but I did it as soon as I heard the noise.
I just wanted to let you know what I did. Disclaimer!!

Since the tapping is back I might try this. I also picked up a quart of Lucas oil treatment as well. Bummer is I just changed the oil in it trying to see if it had any metal in it. I have plenty of filters here but have to get some more oil since it looks like I will be doing a couple back to back oil changes to see if I can get rid of it tapping.