Engine damage with high rpm

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Aqel1982, Oct 19, 2018.

  1. Aqel1982

    Aqel1982 Bobtail Member

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    Jul 6, 2018
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    I was going downhill last week on 5th gear . Rpm was above 36000
    Multiple codes showed up including
    Stop engine light.
    It has been few days in freightliner.
    Could the damage be severe???

    Thanks
     
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  3. aussiejosh

    aussiejosh Road Train Member

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    Airlie Beach QLd
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    Sure its not 3600 rpm not Thirty six thousand even a Formula 1 racing car wouldn't rev that high. When descending a steep hill you've got to put it in a gear that will hold the weight pushing so you don't need to apply the brakes and it should also not allow the truck to do what occurred to you namely building up the revs you were in a bit to high of a gear try going down a few more next time you take that hill/ mountain, also try using your engine brake /jake brake to slow it down if the lights stopped flashing after this happened everything should be ok however when you over rev an engine anything can break the head could drop a valve and do some serious damage.to the pistons. so hopefully you got away with it and can learn from this experience.
     
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  4. wichris

    wichris Road Train Member

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    If it ran 36000 rpm do whatever you can to keep that motor.
     
  5. supersnackbar

    supersnackbar Road Train Member

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    Your Town, USA
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    Most semi engines don't like being rev'd over 22-2400, with 4 valves per cylinder, they tend to float the valves and/or break connecting rods. Smaller diesels like in pickups and passenger cars can handle it, but big displacement diesels tend to come apart...in fact, an over rev like that may have voided the engine warranty.
     
  6. Crude Truckin'

    Crude Truckin' Alien Spacecraft

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    North Dakota, Eh?
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    Let's just say, you definitely didnt do that engine any favors. That's about where things start flying apart in a big engine. 11 years ago, my boss had an MBE4000 make it to 3900 RPM before it blew its guts out on Homestake pass.
     
    bzinger and Rideandrepair Thank this.
  7. AModelCat

    AModelCat Road Train Member

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    Best case scenario you got lucky and the codes were just alerting you to engine abuse. Worst case scenario your engine is toast because the valves kissed the pistons or something to that nature.
     
  8. thelushlarry

    thelushlarry Road Train Member

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    glasgow ky
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    Depending on gearing that should have been about 999 mph.
     
  9. Hulld

    Hulld Road Train Member

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    Upstate NY
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    I hope with a little gearing tweak he can break the 1000 mph mark...
     
  10. stillwurkin

    stillwurkin Road Train Member

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    That engine must've been screaming? Lucky a rod didn't come out the block to shake hands with you.
     
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  11. benjamin260_6

    benjamin260_6 Medium Load Member

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    I'm curious what kind of truck/engine this was?
     
    stillwurkin Thanks this.
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