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Old Jan 9, 2025 | 09:17 AM
  #41  
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From: Oshawa
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You are correct that the most common failure is the spring loaded pin fails on Active Fuel Management lifters. The spring holds the lifter in the open position during heavy loads on #1, #7 and #4 and #6 cylinders (both intake and exhaust) along with the normal lifters on #3, #5, #2 and #8.

When the algorithm detects low load, the Eaton hydraulic system comes on and puts pressure on #1, #7, #4 and #6 cylinders to collapse them and save fuel. Now the crank is turning with connecting rods, pistons, valves all dead. None are participating, instead of suck, squeeze, bang and blow, it is like a geriatric patient in Florida looking for his crayons. Lifeless. They are a drag on the system.

The failure occurs when the spring inside the lifter fails, the hydraulic system shuts off and the spring is now engaged to fully pump up the lifter except it doesn't. The spring has failed. Not dirty oil clogging the hydraulic system, not bad timing for turning on or off the system while the lifter is on the base circle of the camshaft. The spring has failed.

Having a range disabler will not get rid of the spring inside the AFM lifter. It gets rid of the cycling. Only way to get rid of the failure-replace the lifters with normal lifters along with new trays and a new camshaft.
How to Disable Active Fuel Management on a GM Vehicle — Ricks Free Auto ...In Ground Hydraulic Lift Diagram
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Old Jan 9, 2025 | 02:27 PM
  #42  
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Originally Posted by Sam Z
I just joined corvette forum and I can’t figure out how to private message someone.
I sent you a PM, see if you can reply.
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Old Jan 11, 2025 | 05:47 PM
  #43  
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I just got my cat back yesterday from the dealership. They installed a new cam due to failed lifter in #8. They showed me the cam and the lifter. The issue they say has to do with that little wheel not rolling initially but rather skidding and the Rockwell or hardness of the metal not up to par. Basically they were saying crappy steel is the issue and the issue is more pronounced in cars that sit for long periods of time without running being up to temperature regularly.

im just relaying what I was told so please don’t flame me if you disagree. Basically they say it’s not the design but the materials used to build it are subpar. Idk 🤷🏻‍♂️ what to believe but I have a two year warranty and plan to drive it more frequently and not just track days. Hopefully if another torque tube or lifter fails it will be during this warranty period.

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Old Jan 11, 2025 | 06:01 PM
  #44  
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So they are suggesting that your lifter did not collapse but the roller skidded on the cam and caused your issue
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Old Jan 11, 2025 | 06:48 PM
  #45  
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Originally Posted by emfollin
So they are suggesting that your lifter did not collapse but the roller skidded on the cam and caused your issue
well they didn’t specifically say that it didn’t collapse but showed me the wear marks on the roller and the cam shaft. Honestly it didn’t look too bad, kind of like a chrome surface that lost its shine. I should have took pictures I guess, and inquired further. Instead I was asking about if the motor was removed and how to minimize the chances of this happening again. Motor did not come out to change the cam and nothing I can do other than drive it more….basically it’s a crap shoot and I have a warranty so go drive it was what I got out of the conversation. I was also told parts are getting harder to get so hopefully this was my last visit for a while. I’m sorry I don’t have more information for you guys. I didn’t want to repeatedly question them as I felt they were dong me a solid on the repair. I only had to pay for parts and I was just more appreciative then questioning.
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