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Thread: Lifter Failure and Bent Pushrod

  1. #1
    Tuner Trucker82's Avatar
    Join Date
    Aug 2017
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    Bangor, WI
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    105

    Lifter Failure and Bent Pushrod

    I have a client that I performed a DOD disable for, come to me 3 weeks later and said a lifter collapsed on the number 6 cylinder. Another 2 weeks later the pushrod in the number 4 cylinder got bent somehow and is currently being fixed at the local dealership. This was done on a 2014 Silverado. I have attached the stock tune and my Delete tune. Is there anyone that could take a look at the tunes and see if I overlooked something that could cause the described type failures?

    I know the lifter collapse is pretty common. Bent Pushrod, WTF? Any Insight is greatly appreciated.

    Thank you Sincerely, StockOEM.hptAFM Delete.hpt

  2. #2
    Senior Tuner mbray01's Avatar
    Join Date
    Dec 2013
    Location
    Slidell, La.
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    1,015
    generally speaking the only time i see bent pushrods, its because the valve hit the piston. i would be looking for a broken, or improperly installed spring
    Michael Bray
    Rusty Knuckle Garage
    Slidell, Louisiana
    20yr Master Tech.
    Advanced Level Specialist
    Custom Car Fabrication, Customization, High Performance.
    GM World Class Technician
    Shop Owner

  3. #3
    Advanced Tuner
    Join Date
    Apr 2017
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    On my personal truck. I had the DOD turned off in the tune and only that changed. And my L86 broke a valve spring as I was pulling into a parking lot. No hard pull, no racing, just cruised down the highway and when I pull off the highway and it just started running really rough and would start back up. Broke on number 5

  4. #4
    need to replace the dod valley cover. had same issue on my 2014 5.3 with only 3k miles

  5. #5
    Advanced Tuner
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    Apr 2017
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    Why would that cause a bent push rod???

  6. #6
    Advanced Tuner IARLLC's Avatar
    Join Date
    Aug 2016
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    942
    Yeah, the valley covers had TSBs for poor oil control. The lifters had TSBs coming apart... BUT

    I think that the real issue was the weak springs they installed until half way through 2015. They were running the yellow springs until then and we have had a number of them break...ALWAYS on the heavy intake valve. There is usually light valve to piston contact if it was at RPM when it happened. The valves are usually not bent by this. The plastic intake warps pretty bad if they don't shut it down right away. For whatever reason, I have seen it on cylinder #7 more than any other...x3. About half way through 2015 they started coming with the blue springs which I am pretty sure are Vette parts. I have not had any of those break yet.

  7. #7
    Tuner in Training
    Join Date
    Jan 2020
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    15
    I have a 2015. While passing someone on the way to work one day it dropped #7 and I had to abort while passing and get back behind them. When the dealer called me they said I had 0 compression in that cylinder! Pushrod bent and hung the valve open. No other changes except DOD turned off. So yes, it can happen!
    New to tuning, but not to cars. Just here to learn!