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  1. #1

    Default Seized 7.4L engine story and Question

    1995 GMC Sierra, Bucket Truck, 55,656 miles

    Story: 35 MPH #1 piston came apart and the connecting rod (which was still going up & down) beat the big pieces into little pieces; this smashing process bent the connecting rod until it punched a hole in the cylinder wall at which point the wrist pin lodged in the hole and stopped all movement.

    Purchased a Re manufactured engine (Mexico) with a flat tappet camshaft that needs to be broken-in properly, which leads to my question:
    When this engine starts for the very first time, would a new oxygen sensor be damaged by the burning of oil in the cylinders; I'm thinking of leaving the old sensor in until after camshaft break-in ? ? ?

    My History, I was born in 1946 and stopped working for an employer in 2010. I served aboard the USS INTREPID CVA11 in the 1960s. The Intrepid is now a museum in NYC. As a former crew-member I did volunteer duty on board 2009 & 2010.
    Last Year I volunteered at a water powered mill in Wilmington, DE.

    In 1993 I replaced a (4.3L) 267 SB with a (5.7L) 350 SB in a 1979 Chevrolet Malibu wagon (everyone called it a sleeper). That was the extent of my engine swapping until now.
    My SON just bought an electrical business from his employer who was getting out of the trade; the bucket truck was part of the deal. Less than a year later the engine seized and he wasn't getting the work he was hoping for (no money for the bucket truck). Enter volunteer DAD with the money for the engine and the tools to do the work.
    Thanks for any advice !Click image for larger version. 

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    Last edited by 7.4L.....volunteer; 05-05-2013 at 10:16 AM.

  2. #2
    Sr. Engineer
    Join Date
    Oct 2010
    Indianapolis, In


    Good story and I hope buisness picks up for your son. I do not believe the extra oil would damage the sensors but since you are replacing them and have the option to fire and run on the old ones, I would and swap them out after it is running ok.
    2000 GMC YUKON SLT, 5.3L tow pkg, G80 rear/w 3.73 gear

  3. #3


    Thank God for dads (I think that's what my kids say)

    Welcome aboard.

    '09 Avalanche LTZ - Black
    '05 Envoy XL (sold)

  4. #4


    I would run it with the old O2 sensors in, I don't think that the oil will damage the new one, but why risk it.

    1995 Silverado 4x4
    6" BDS Suspension Lift-3" Body Lift-Add A Leaf in rear -Trailmaster SSV Shocks-Duel Steering Stabilizer Kit -AirAid Cold air intake-
    4.56 Gears with Detroit Auburn Locker-Pro-Comp Traction Bars with duel shocks-Aluminum Skid Plate Kit-38.5" x 16.5" Mickey Thompson Baja Claws-Constant Dropping fuel gauge

    2005 Yukon XL Jet Power Programmer, Bilstein Shocks, Bilstein rear springs, Helwig Anti-sway bars, EGR Window Visors, EGR Hood Shield, Denali Headlights, Headlight harness upgrade, GE NightHawk Bulbs, White Night Rear lighting system, Russell Braided SS brake lines, PowerStop Brake pads, PowerStop cross drilled and Slotted Rotors,
    2002 Silverado ext cab 2wd (Sold)
    2003 Yukon XL (Totaled)

  5. #5


    I have to say, the part that interested me the most about this post was the picture of the shattered piston. "Wife's Fry Pan" Lol If I did that, I'd be sleeping on the couch for awhile.
    94 Chevrolet K1500 4x4. 5.7L 350, 5-speed (AKA Betty) Or Rust Bucket...depends on if I'm mad at her.

  6. #6

    Join Date
    Jun 2006
    River Ridge Louisiana-4 miles W of New Orleans-didn't flood-water stopped 800 yards away.


    Gotta agree with James.
    BEFORE I was married-1980 maybe
    I read something about lubing a motorcycle chain by putting it in motor oil-then heating the oil

    Yeah-put it in a BIG frying pan-on stove-electric.
    Horrible odor in apt-but it gets worse
    It caught fire-duh oil burns-especially hot oil.
    Didn't have a lid to smother it
    so I tossed a few lbs of laundry detergent on it
    Freakin mess
    My girlfriend-now wife- saw my not great clean up job-
    Hmmm married me anyway-but in 1984!!

    In any case-yeah leave those sensors in there-and being machinery oriented-and old-(I'm only 62 you are an older duffer than me!) you will be concerned with oil supply
    The break in usually has something about pumping the oil around the engine BEFORE starting it
    Most folks don't have a way of doing this
    So I just crank the engine with the plugs out-so not much load on anything-use engine oil pump to pump oil around
    Gotta pump it quite a bit-many hits of starter(charge that battery up-or have a second one ready)-1 minute or more of "run time"

    Bet someone here has a better "shade tree way to do it"
    Think I also would pull valve covers smear assembly lube on stems etc"-maybe spray lube from under engine-oil pan off-smear spray assembly lube everywhere.

    Last edited by phoebeisis; 05-12-2013 at 09:27 AM.
    1998 suburban-
    1/2 ton

    199500 miles

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