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I have a 2015 Silverado 5.3 that had a misfire on 7th cylinder. Ended up taking it to the dealer and they said I had four bad lifters. Truck has 88k they ended up warranting the work. Has anyone else have this issue in here seems like a known issue now that’s I’m researching..

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It's a very well known issue. This stuff dates all the way back to vehicles made since 2005 when this system first started.

 

2014+ trucks is either the lifters or injector issue for bad misfire problems.

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2 hours ago, CamGTP said:

It's a very well known issue. This stuff dates all the way back to vehicles made since 2005 when this system first started.

 

2014+ trucks is either the lifters or injector issue for bad misfire problems.

Cameron:

 

Question. AFM Lifter failures fall into three groups. Defects in lifter materials/craftsmanship OR oil related. That is lack of oil maintenance in that the screen plugs partially and mistimes a switch physically breaking the lifter pins OR oil aeration. Any idea on the percentage of failures to each condition? 

 

Secondly, is it not also true that AFM motor type lifter failures also happen to NON-AFM cylinders? Primary failure in the check ball/spring and yet are attributed as AFM lifter failures? 

 

You seem to have more unbias knowledge on this topic than most. Your thoughts please? 

 

Thank you in advance. 

 

Grumpy

Edited by Grumpy Bear
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I think the idea and craftsmanship of the AFM system is good, I mean they had to come up with something for the CAFE deal. The materials and for some, poor care was a downfall. Just the way the AFM lifter is activated was just asking for an issue to happen at one point. Solenoid failures, poor oil conditions that hurt parts and plug filters. Having a spring system on a lifter that is constantly working on and off in city driving and so on.

 

I couldn't even guess the percentage of each type of failure but I've always seen the same type of problem. The lifter itself is almost always collapsed and the VLOM is second in line for issues.

 

The regular lifters can for sure have the ball/spring be an issue. Could make them really noisy as well but yet they will still run making noise forever it seems. Camshaft damage will take out the rollers too. Not sure how you'd ever be able to prevent that when it's a metal quality issue.

 

I dunno if that helped answer much, it's past my bed time lol.

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I had 1,3,5 and 7 replaced. CEL and Stability Control lit up, rough running truck, straightened up and ran fine on the way to the dealer. Codes pulled, cyl. 7 had 6,900 misfires, could not duplicate and sent me on my way. One week later, happened again, made it to the dealer and left it running for 45 minutes waiting for them to open their doors, stunk up the entire lot running like poop. Same codes, this time replaced the Lifters. Funny thing is, the tech on the first trip told me he was going to replace all the lifters, but then I got the call saying the GM refused being the truck was running fine despite the codes.

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11 hours ago, CamGTP said:

I think the idea and craftsmanship of the AFM system is good, I mean they had to come up with something for the CAFE deal. The materials and for some, poor care was a downfall. Just the way the AFM lifter is activated was just asking for an issue to happen at one point. Solenoid failures, poor oil conditions that hurt parts and plug filters. Having a spring system on a lifter that is constantly working on and off in city driving and so on.

 

I couldn't even guess the percentage of each type of failure but I've always seen the same type of problem. The lifter itself is almost always collapsed and the VLOM is second in line for issues.

 

The regular lifters can for sure have the ball/spring be an issue. Could make them really noisy as well but yet they will still run making noise forever it seems. Camshaft damage will take out the rollers too. Not sure how you'd ever be able to prevent that when it's a metal quality issue.

 

I dunno if that helped answer much, it's past my bed time lol.

Always helpful. Could have answered anytime so thanks for the extra and sorry you missed some sleep. Not intended but apricated. Lot's to sift through here. 

 

I've been thinking about the cam lobe damage after reading a article in another thread some months back that was talking about these timing failures. How the system is designed to collapse AND EXTEND the lifter on the base circle. When a timing error occurs wherein the lifter extended on the open ramp the forces are HUGE. I have a picture similar to piston assisted valve closing type failures. Often the pushrod is bend as well, yes? Wouldn't make much difference what the metallurgy was in that case. Pretty much what would happen with aeration or screen plugging. In that case what looks like a metals issue is really a lubrication/lubrication maintenance issue.

 

I've read reports of bad batches of lifter but mostly pre 2014 although it can happen anytime, granted. I've even seen some liters, which are a centerless ground product, that looked like they should have never made it in a motor. A QC issue, agreed?

 

My guess would be that the clock in the PCM and solenoid system doesn't get 'confused' as to where it is in it's cycle, unless of course there is a cam/crank position sensor failure. Miss timed events then would have to be hydraulic issues. That is, while oil is incompressible, thus the reason for it's use, entrained air, aeration, or cavitation voids, as when oil is forced through a screen at a rate faster than it can pass, as would be the case if say 75% of the screen were plugged (debris/varnish) delay the lifter EXTENTION ONLY as the screens on the inlet side. Whew, long sentence, sorry. Hope it made sense. Does in my mind but  you know well the trouble I have getting thought on paper in a way others understand.

 

I suppose it could also happen in the event of a solenoid sticking? That is it gets its signal on time but 'varnish' delays application a nanosecond? Possible I guess. A solenoid is not direct acting as a gear would be. 

 

That same article suggested shorter OCI's. I've seen this before with the 2.4L motor ring issues where in those motors had the OLM reprogramed for shorter OCI's. Terrain? Verano? I'm starting to ramble...….

 

It would seem then that a good number of failures are oil maintenance related. Even when then look materials related. And yes some design, metals, QC issues, enough to keep the waters muddy.

 

One issue confuses me however and that is aeration. I normally think of this as a windage issue in high RPM motors (towing?) but there is allot of windage control designed into these motors. Oils have antifoam agents. Still those can be overwhelmed with fuel/water/antifreeze contamination. Perhaps less confused that I thought now I see in on paper. :) Again oil maintenance.  Hummm.

 

On 3/22/2020 at 10:44 AM, Sean D said:

I have a 2015 Silverado 5.3 that had a misfire on 7th cylinder. Ended up taking it to the dealer and they said I had four bad lifters. Truck has 88k they ended up warranting the work. Has anyone else have this issue in here seems like a known issue now that’s I’m researching..

Yes the issue is real. What's in question is how much control do you have over it? Perhaps I should say how much you HAD over it. Nothing is more hotly debated than oil maintenance. I'm not about to question you about this. I will share with you that I'm know as an 'over maintenance' sort. I replaced the screen to the VLOM somewhere between 50 and 75K and still found debris in it. I've added it to my list of regular replacement items. The ones under the solenoids on the VLOM are not serviceable. 

 

All that said. It isn't as common as it looks if you look at the entire population of motors produced. 

 

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