Click Click Boom!!!!!

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Goodysnap, May 14, 2020.

  1. daf105paccar

    daf105paccar Road Train Member

    Apr 15, 2012
    Does the ECM register all rpm's?
    Cattleman84 and tommymonza Thank this.
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  3. Goodysnap

    Goodysnap Road Train Member

    Jul 12, 2017
    I have gone through all reports and found nothing stored in fault codes or data that recorded such an event.

    In my 8 plus years with Paccar this is a first for me with this engine, from EPA 10 to current. I have seen 1 tube bent maybe 2, 1 rocker broke. Never all 6. Plus all valves are bent and no compression.

    It screamed for sure. Maybe even north of the 3k @spsauerland mentioned.

    Wish I had a number, but I don't. ECM was sleeping? Key off?
  4. FoolsErrand

    FoolsErrand Road Train Member

    Sep 15, 2017
    I have spit two pushrods in my life. Both were exhaust side. One on a p-pumped 6bt and one on a mechanical dt466. Both run pretty hard.

    The 6bt i just hammered it straight on a curb stone, relashed it and kept going. Engine is still together in a parked truck 900 miles away.

    The 466 was a fresh rebuild, like 4k miles on it. The assembler put valve seals on instead of oil deflector shims. The old 466 was a low flow top end and the newer NGD series is higher but theres an inbetween model with 3/8 stem diameter and high flow so every kit has seals and shields. He chose wrong. The exhaust valves are hotter so they are the first to overthin the oil and gall the shaft in the guide. The guides were almost worn into the head casting whe it spit the pushrod, chunked a corner of the rocker and i tore it down. The valves walked so much they had eating into the bores badly. I put in new guides and valves, did another valvejob and put it back together.

    A dropped exhaust pushrod will always sound like a basketball being dribbled on concrete inside the engine. Youll feel pops of air coming back out the intake. Its the compression being stuck in the bore until the intake stroke opens it and vents.

    Look at your valve stems for scoring and guides to be shot. Low oil pressure in the head will do it. MAYBE being way overheated too. But it starts with galled valves sticking in the open position. The rocker arm moves away, the pushrod falls down and the rocker crushes them. Then its stuck in the tube and holds the valve open for the piston to eat it.
    BoxCarKidd and speedyk Thank this.
  5. lilillill

    lilillill Sarcasm... it's not just for breakfast

    Nov 7, 2007
    Possum Booger, Alabama
    "Crap!!! It's running away down this hill! I better shut the engine off. Yeah, that'll make it stop."
    SL3406, Itsbrokeagain, baha and 5 others Thank this.
  6. 062

    062 Road Train Member

    Oct 20, 2013
    If you remember the rumor about the first electronic Detroit’s that you could push the clutch in,turn the key off, then back on and pop the clutch to override the speed governor.
    little cat 500 and lilillill Thank this.
  7. pushbroom

    pushbroom Road Train Member

    Sep 1, 2012

    Autoshift or standard?
  8. Goodysnap

    Goodysnap Road Train Member

    Jul 12, 2017
    Tis a manual.
    pushbroom Thanks this.
  9. AModelCat

    AModelCat Road Train Member

    Jul 7, 2015
    Key off? Wonder if she was sucking in an external fuel like H2S or propane? Driver shut the key off but she just kept spinning, running on vapours?
    Isafarmboy and Shawn2130 Thank this.
  10. jamespmack

    jamespmack Road Train Member

    Mar 25, 2014
    Could it have been towed with shaft in and in a lower gear? Key off?
  11. Ridgeline

    Ridgeline Road Train Member

    Dec 18, 2011
    Somebody used ether with glow plugs?
    Cattleman84 Thanks this.
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