Replaced afm lifters

[TX_TahoeMama21]

Not too many people here repair the AFM system. Viewed as a ticking time bomb, moving forward with a delete after an AFM lifter collapse is the norm.

I do recall that GM says that anytime the VLOM is removed, it should be replaced.

Considering nothing else was touched, the most likely culprit is a leak under the VLOM plate. This posting reads like the gasket around the perimeter of the plate was replaced.... I don't think that's a real option. The integral gasket involves some disassembly to replace, also covers the oil towers in the middle of the valley. If you somehow just replace the perimeter, the new gasket will increase the height of the plate slightly.... And the existing seals over the towers won't be compressed enough.

I think a new VLOM plate is necessary, torque down properly. (With new OEM GM oil pressure sending unit with new screen underneath)

If you still have an oil pressure issue after that, then I would pull the pan, replace the pickup tube o-ring and the pressure relief valve mounted inside the oil pan on the driver side. While you're there you can remove the oil pump pressure relief spring and valve, make sure it's clean and not gummed up and sticking.

The best all around fix, however, is simply do the AFM delete for long-term reliability.

I live in Texas have a 2021 Tahoe 5.3 haven’t had issues yet but would like to know about how much does a delete cost? I’ve got 70.9k miles on it.

 

[pronstar]

I live in Texas have a 2021 Tahoe 5.3 haven’t had issues yet but would like to know about how much does a delete cost? I’ve got 70.9k miles on it.

I paid 30 hours shop labor ($125/hour) at a shop in Fort Worth, I supplied the parts.

They pulled the motor to do the work, and I had a bunch of other parts replaced “while you’re in there” since I didn’t have to pay to get to them.

 

[rdezs]

I live in Texas have a 2021 Tahoe 5.3 haven’t had issues yet but would like to know about how much does a delete cost? I’ve got 70.9k miles on it.

You're kind of in the wrong subform to be asking, this particular section is for a 2007 to 2014 models. You'll probably get more pertinent info in the correct forum.....

 

[Marky Dissod]

You're kind of in the wrong subform to be asking, this particular section is for a 2007 to 2014 models. You'll probably get more pertinent info in the correct forum ...

Based on the vehicle he's asking about, true, but how much less does deleting AFM cost for a Gen4 V8 vs a Gen5 V8?
Guessing that deleting DFM on a Gen5 V8 would cost more due to the price of the tune?

 

[j91z28d1]

in general LT is more expensive to work on than ls.

what cam would you even use? unless you went aftermarket. which I wouldn't really want to do

 

[Marky Dissod]

in general LT is more expensive to work on than LS.
what cam would you even use? unless you went aftermarket. which I wouldn't really want to do

If it's an Engine Half@$$ cam, you need a non-Half@$$ cam.
If it's a Cylinder Confusion cam, you can just keep that cam, provided your tuner can disable Cylinder Confusion.

 

[rdezs]

With the Gen 5, the way I look at it.... GM took a bad idea, which is a bit of a pain to delete in the LS engine but very doable, and they doubled down on their idea and made things more complicated. (And created new issues that didn't exist on the LS engine) I'm afraid they chased off a lot of customers.... I for one won't buy a GM newer than a 2014.

The thing that's even more troubling, is that all the manufacturers are being very quiet about the upcoming addition to the emission system, that I think goes into effect for all models in 2027. I know that some 2026 is already have it. It's a gasoline particulate filter in your exhaust. I suspect they've been quiet about it because they know people don't want it. There's no DEF fluid like the diesel has.... About all I've heard about it is about once a week you have to maintain something like 3,000 RPM for 30 minutes for it to regenerate/clean itself.... And if the light comes on, it's too late, the engine will derate and off to the dealer.

Look it up online, gasoline particulate filter. It seems even the media hasn't been talking about it, it feels like even the automotive magazines have had a total block out on the subject, probably in collusion with the manufacturers as no doubt it would affect sales.

That's my two cents....

 

[j91z28d1]

from this bob the oil guy thread. it seems like it's nothing new in other countries.

https://share.google/xjslXpdpVZjIs5O8W

mainly a direct injection turbo issue. probably won't be on all cars. but that they say the Porsche 911 has them. I guess it doesn't hurt exhaust flow much. atleast when new. something else to replace when fouled out I guess.

I also don't feel like. owning anything newer lol.

 

[rdezs]

Yeah, it's been in use the past couple years around the world. Major maintenance issues. Unfortunately Bob the oil guy is a pure environmentalist and focuses on the benefits of clean Air. Even the statistics from Ford on their 5.0 coyote motor so that for 2027 when they start using the gasoline particulate filter, the torque and horsepower ratings are reduced. Same goes for the EPA rating on fuel economy.

With the Chinese building multiple new coal burning power plants every month, with no emissions regulations.... We could all stop using all gas and Diesel engines here in the US... And thanks to the Chinese the air quality would continue to decline. Sort of makes all the emission equipment we pay for totally pointless.

 

[rdezs]

Be cautioned about any of these new vehicles if your commute is shorter than 20 or 25 miles across town. When that check engine light comes on for the GPF, and it's too plugged up to clean itself..... You're at the mercy of the dealer who will have to remove it to clean it and potentially replace it. Driving the car not as it's intended is not covered by warranty. This is the big issue the rest of the world has lived with, and now it's going to be dumped on us.

 

[rdezs]

Just imagine.... Your engine has been derated because that light came on. And first they want you to take it on a 50 to 100 Mile drive maintaining 3200 RPM to see if it will clean itself. So what, after work take a 100 mile trip in third gear on the freeway? And this saves emissions? No way in hell I would ever purchase one of these vehicles.

 

[tooleyondeck]

I for one won't buy a GM newer than a 2014.

For what it's worth they knocked the 6.6 L8T out of the park. I'm surprised after the few members on here have successfully swapped them into K2X SUVs, this hasn't become a more popular option for those who want a "forever" vehicle.

 

[West 1]

I bet I repaired a dozen GM AFM lifter failure trucks over the past 6 years. Never had one issue. I always installed a new improved design AFM lifter VLOM along with all new lifters both standard and AFM lifters, the lifter retainers, oil pressure sending unit and pulled the oil pan to repalce the Oring on the oil pump pick up, Fel Pro Head Gaskets Intake Gasekts and Head bolts. New by pass valve in the oil pan installed. Usually a new Water Pump thermostat and all new hoses while in there. If there was an oil cooler the lines got replaced because they were always leaking. Do the job complete and you will have success.

You never know if the VLOM has failed causing your bad lifter or if the lifter has failed. The new VLOM's on Rockauto were only $170 and you had to remove it to repalce lifters. Can't see not replacing that part with new also. I usually used the GM improved design but a couple times the GM part was not available so I used the Dorman part and it worked also.

You did a lot of work. Sorry it was not good on the first try. At least on this second repair the head and lifters will stay on.

 

[Mlstammerjr]

Ok update. I replaced the vlom and the oil pressure sensor. I now have a code p300 for a random misfire and the engine no longer sounds like it’s starving for oil but the pressure guage drops to 0 randomly. I had my buddy hook up his obd scanner and it had two faults, the p300 and a fault on the oil pressure sensor. I bought a cheap amazon sensor so I wouldn’t be surprised if it just came bad. Plus I took it off the old vlom and put it on the new (the new sensor) so I wouldn’t be surprised if that somehow messed it up. I’m not sure where to go from here. Maybe I messed the intake gaskets up when I put the intake back on? It fought me getting back into place but all the bolts threaded it and from what I could tell the gaskets were seated right. Any advice would be appreciated. I’m so tired of working on this thing just to find new issues

 

[rdezs]

1. Did you replace the VLOM with a new unit?
2. Cheap sending units are a waste of time and money.....rarely reliable.
3. Random misfire...depends on which cylinders, means different things. (AFM vs non-afm cylinders, or both?)
4. Verify oil pressure with mechanical gauge. Either off a T fitting at the sending unit, or off the oil port on the drivers side of engine, towards the front, just above the oil pan behind the power steering pump.
5. It can easily be a vacuum leak causing the random misfire....did you use a new intake gasket? Intake tube properly connected? MAF?
6. If it's oil pressure related, pull the pan...replace oil pickup tube O-ring, replace relief valve in the pan, and remove and clean the relief valve in the bottom of the oil pump. If that doesn't fix a low oil pressure issue, most likely one of the front 2 cam bearings. (That's assuming you installed a new VLOM plate that comes with the gasket attached to it)

 

[j91z28d1]

definitely do a mechanical oil pressure gauge test. they are pretty cheap on Amazon. most likely oil pressure sensor is bad. I went thru a few so called oem ones off Amazon, but after inspection, I'm pretty sure they were fake.

I replaced 3 of them between 2 cars over a few months before realizing. then went to rock auto and paid more for their oem one, and the other I just stopped at a dealership parts department and asked if then would match the price. they got close enough. Haven't had either of those fail yet. but that said I have a friend with a c5, same sensor. Amazon failed. rock auto failed twice and he gave up and got a autozone one and oddly it's been good for a year. the others failed within months. bottom line is no one makes a known great sensor for these things. all replacement parts are suspect

the miss fire. after you make sure it has oil. pressure, have your guy with the scanner pull up the live misfire data. it should show which cyl to check. I've seen everything from a bad plug wire, to a loose spark plug cause misfires. it can be a bit of a process to find.

also, I don't recall. but where did you buy the afm lifters from? I've seen a few threads over the years of cheap ebay/Amazon afm lifters being a fail out of the box and have to go back in with milling or gm lifters.

 

[Foggy]

Random P0300 misfires could also be: fake spark plugs and/or wires
make sure to get them from a reliable source : NOT Amazon is what this means.
Fake parts are everywhere. Your local parts store will be more expensive than
mail order, but will be the actual parts. Use AC Delco plugs. Wires: just use a name brand