Wow, I got a lesson in LS lifter failures!

[alrock]

Well, my 2020 Silverado with the 6.2 (L87) had a big failure on Sunday while driving to a nice dinner. A lifter failed in the #8 cylinder and likely bent the pushrod, damaged the cam, etc. Reading online, it appears that many attribute this issue to oil starvation from the AFM (cylinder deactivation) system on this engine. This is a bit different than the last gen engines that would cut off 4 cylinders as the L87 can go as few as two.

So my goal was to delete AFM and maybe upgrade the cam a wee bit since it was going to torn apart anyway. I started with AFM delete kits for this engine and there only appear to be two good vendors out there (Texas Speed and Brian Tooley Racing), and Texas Speed is sold out. Before I pulled the trigger, I contacted Kelly at PCMofNC for some advice. She said that these computers (E90) are specially controlled by GM, at least in the Silverados. The computer has to be sent to HP Tuners just to be unlocked, and that's about $1000. Then programming at PCMofNC could range from $100-$600 depending on what options I chose. Nope, not going to go that route. This would likely put the repair and build close to $4000.

Reloader has a good transmission and engine shop. They rebuilt my transmission and one or two for him as well. He quoted only ~$2400 for the cam, lifters, push rods etc. I'll be adding in a few wear and tear parts to be replaced like the water pump, timing chain parts. The Silverado is on its way there now and will probably hang out for a week or so.

I appreciate the AAA shop that initially received the truck. With a AAA tow, the first hour of diagnostic is included and he only charged me one more hour at $91. They did a lot of work, including taking off the valve cover and seeing that the #8 exhaust valve was not moving. I'll be sending them some Crumbl cookies in appreciation.

 

[06 H3]

I’m so sorry to hear that. I have heard of these issues with the later model AFM unfortunately. I reached out to one of my mechanic friends and he said he’s seen many in 10-15k mile range.

 

[3Hummers]

I also have heard many horror stories. A friend of mine works at a chevy dealer and said get the extended warranty or trade in when the warranty expires.

 

[08H3]

Sorry about your luck. I know the AFM on these can cause issues, but the overall failure rate is still really low. Someone has to be the guy that gets the bad luck, and I really hate that it happened to be you this time. For all that’s involved, I think you got a fair deal on the repair.

 

[cgalpha08]

Sorry to hear that Alex, ive got the predecessor engine, the 6.2 L86 in mine and luckily only goes down to 4 cylinders, i am considering getting one of those cheap AFM disablers since i already have 104k on it

 

[06 H3]

My first 5.3 had AFM and disabled to 4 cylinders. I had left the AFM lifters, but electronically disabled it with good luck. The 5.3 failure I had had nothing to do with AFM

 

[Alpha X]

Are you over 60k miles? The powertrain warranty on a 2020 Silverado is 5 years/60,000 miles.

 

[deserth3]

Damn that sucks.
My 2017 Silverado is at 116,000. I'm waiting for it to go.
You should ask reloader if he can put an 8.1 L18 engine in for you.

I was reading there is a Tahoe option for a 6.2L without AFM. So a non AFM engine should exist.

 

[alrock]

Sorry to hear that Alex, ive got the predecessor engine, the 6.2 L86 in mine and luckily only goes down to 4 cylinders, i am considering getting one of those cheap AFM disablers since i already have 104k on it

I was going to go with the Range disabler but my mechanic said he can disable AFM in the computer for about $370, which is labor/overhead and 4 HP Tuners credits. I trust that approach more than the Range, reading how many customers have varying results with Range. AFM disabling always works, but other weird things happen to some too. He mentioned it's not expensive to turn off AFM on this computer, but seconded that programming is a whole different story. I'll be just under $3000 for all of this work which I'm okay with consider the scope of it.

Are you over 60k miles? The powertrain warranty on a 2020 Silverado is 5 years/60,000 miles.

69,000 miles. I don't feel like fighting GM for a goodwill gesture, plus I'd rather fix it right. They usually only repair the affected bank, and do the absolute minimum, I'm replacing both banks, installing a new cam, but also new water pump and timing set. The mechanic doesn't like GM's water pumps or timing sets, so we're going with Melling.

 

[alrock]

Update: the engine was torn down on Wednesday (he's been really short staffed, but I trust the guy so I'm fine with the wait.) Actually, I think it was #7 that failed. Anyway, there was one bent rod, and both lifters had failed in that cylinder. The bent rod one obviously had an oiling and compression issue with the DFM lifter. On the other one the roller failed and rolled like the bearings were gravel. It was flat-spotted in multiple places. One valve will need to be replaced.

I found out Texas Speed does (or should) have the parts in stock and he's ordering those today. I asked him to use his judgment on LS7 lifters or those from Comp Cams or Morel, which are modest cost upgrades. So I should be getting 16 new non-DFM lifters, new cam, new valley plate, new bolts, gaskets, etc. New Melling water pump and timing chain assembly. DFM delete in the computer.

Paul (the guy) added: "I really f***** myself on the quote. I figured these were pretty much the same as an 2017, and that is 21 hours. This one is listed as 32 hours and does require that much more work". I'm going to work with him on the bill as that's not fair to him. Yesterday they could not get the crank bolt loose using an impact with a 1400 ft. lb. rating. I don't know if that's a tired gun or what, but they'll git er done today. Unless they break the bolt and have to pull the engine.

We took a look inside at the top of the valves to check out the buildup of carbon (actually, a tar like buildup) inside. I was hoping it was modest and a chemical clean like Berryman's GDI cleaner would do the trick. It was more substantial than that so he's going to tear down the heads and fully clean everything. This pic shows an average level of buildup - some were significantly worse, some were a bit better. Paul seems lo love working on heads - he really enjoys the machining work though these won't need much of anything in that regard.

 

[LagunaH1]

I feel your pain. My truck sounds a lot like the dreaded “Hemi Tick” all of a sudden.

 

[alrock]

Ugh, sorry to hear that.

Oh, I should clarify that my engine is an LT. Not that it matters much for this issue.

 

[f5moab]

AFM (A F***ing Mistake)

But own no GM's and most likely never will again.....

(Surprised to see the old guy stop by?)

 

[rascole]

Ouch. could the intake tar be from the 0-20 oil recommended?

 

[alrock]

I believe that tar is in every gas direct injection engine. Valves are no longer getting washed by gasoline since the spray is in the cylinder, not in the head.

And F5, damn glad to see you!

 

[f5moab]

Still kicking around in Idaho....stop in from-time-to-time to see what's happening.

Yes, DI engines do have that problem with the intake valves but AFM made it happen faster and nastier.
There used to be a module you could plug into the DLC under the dash that would cut off AFM; not sure what model years it was good for.
Try silveradosierra.com/ used to have more info on the disabler for the AFM engine.

 

[3Hummers]

Doug, good to see that you are still kicking. Drop in more often.

 

[alrock]

There used to be a module you could plug into the DLC under the dash that would cut off AFM; not sure what model years it was good for.
Try silveradosierra.com/ used to have more info on the disabler for the AFM engine.

Those devices are still around and still work. Range is one brand. I just chose to make it permanent. And for the record, my truck is still at the shop and the engine is still out of the truck.

And yes, Doug, it's great to hear from you!

 

[cgalpha08]

Still kicking around in Idaho....stop in from-time-to-time to see what's happening.

Yes, DI engines do have that problem with the intake valves but AFM made it happen faster and nastier.
There used to be a module you could plug into the DLC under the dash that would cut off AFM; not sure what model years it was good for.
Try silveradosierra.com/ used to have more info on the disabler for the AFM engine.

I have this in mine, drives like a different truck at the lower demand throttle inputs. I'm guessing the previous owner didn't have one, so im hoping I can prolong the inevitable for as long as possible lol If it blew id probably go Alex's route and just permanently delete it.

 

[deserth3]

Interesting. I got the Range AFM disabler when number 4 the vacuum pump failed and was anticipating eliminating that. When I tried the disabler, I didn't notice any difference in power or how the engine runs.

 

[f5moab]

Power increase will primarily be on a roll when the computer has cut off some cylinder to go into AFM mode. Example, cruising down the road at around 40 and it is in AFM than you hit the throttle it takes a second to get all cylinders firing. Off the line acceleration should be about the same, since all cylinders will be firing. Your gauge should show a V8 or V4 mode and believe the V8 was in red, V4 was in green...not sure been a while.

 

[alrock]

FYI, still don't have the truck back. Shop figured out the computer is now strongly encrypted (since 2019) and it require sending it to HP Tuners just to unlock ($500), plus $400 to turn off AFM, plus shipping. I warned him about this but he didn't take heed.

Holley is supposed to be releasing a new i3 tuner in the next couple of weeks for $600 that gets past the encryption, allows you to turn off AFM and also allows the owner to put in tunes, from the Holley pre-configured ones to vehicle-specific ones. Waiting for that device to be released.

 

[06 H3]

FYI, still don't have the truck back. Shop figured out the computer is now strongly encrypted (since 2019) and it require sending it to HP Tuners just to unlock ($500), plus $400 to turn off AFM, plus shipping. I warned him about this but he didn't take heed.

Holley is supposed to be releasing a new i3 tuner in the next couple of weeks for $600 that gets past the encryption, allows you to turn off AFM and also allows the owner to put in tunes, from the Holley pre-configured ones to vehicle-specific ones. Waiting for that device to be released.

Damn it, I wish I knew. I already have HPtuners, it would be $100 for the license directly tied to your vin vs the $500. I could have mailed you my HPTuners setup, they email the file to you, you plug it in and you upload it to the truck.

 

[alrock]

157 days later and the truck is back. Wow, that was a journey. The last delay was waiting for Holley to release their newest product, which is a handheld tuner with the ability to unlock the ECM and TCM on these newer trucks. Before this product, you had to send your ECM to HP Tuners or Holley (and presumably others) and it was hundreds of dollars just to unlock. Programming was on top of that. There were issues updating the tuner and he spent six hours getting it unlocked and tuned, with a lot of that time on the phone with Holley. Even without the challenges it would have probably been at least a two hour process. We got one of the first couple of dozen that were produced so I'm sure there are programming bugs to work out.

Heads were cleaned and rebuilt and all of that buildup from the direct injection engines is gone. Only driven it a bit so far but will drive it more today and change the oil again tomorrow just in case there are any tiny metal bits from the new parts in the engine - lifters, pushrods, camshaft, valves, valve seats.

Chris, the unlock for these ECMS is eight HP credits ($400) plus shop labor when applicable, and you need to have a certain version of HP tuners, and maybe specific equipment as well. Not as easy as older tunes.

 

[LagunaH1]

Wow, what an ordeal!

My olld goat (2016 Ram Power Wagon) has oddly decided that it is NOT needing a new cam / valve lifter repair at the moment. Since that one time where it made a terrible noise for minutes after cold start, it's been running very normal, and made no unusual noises.