Do jake brakes damage the engine?

Discussion in 'Questions From New Drivers' started by John Bertucci, Nov 29, 2020.

  1. John Bertucci

    John Bertucci Light Load Member

    Jul 5, 2019
    I just bought a used truck, both the Jake brakes and the cruise control were disabled in the computer settings. I asked the salesman why in the hell would you disable the jake brakes and he tells me that they are actually bad for the engine and cause a lot of wear and should only be used in downhill application when its absolutely necessary and the damage you're causing to the engine by using it to brake is more expensive than brake pads. Can anyone verify or debunk this?

    Thank you
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  3. D.Tibbitt

    D.Tibbitt Road Train Member

    Apr 26, 2013
    Gettin' down westbound
    Tell him to pass the crack pipe
  4. spindrift

    spindrift Road Train Member

    Dec 2, 2014
    That salesman suffers from a whole lotta' WOW.
  5. Michael 247

    Michael 247 Medium Load Member

    Nov 20, 2017
    0 wont hurt the Engine..But I dont leave the Jake Switch on all day...Just use the Jake as needed..I think using the Jake Excessively is a little rough on the Drive Train..Especially in lower gears ...
  6. Moosetek13

    Moosetek13 Road Train Member

    Nov 1, 2010
    Burnsville, MN
    It's that cruise control that really messes things up.
  7. okiedokie

    okiedokie Road Train Member

    Jun 13, 2011
    I've heard that Jake shifting is detrimental to the engine. But in certain off road applications I did it.
  8. LoboSolo

    LoboSolo Medium Load Member

    Jun 21, 2013
    Highway 20
    Truck salesmen are more full of #### than dispatchers.

    I heard a truck salesman telling a prospective buyer that automatic trannies are the bomb, and you'll save fuel. If your drivers don't like them, then just #### can them and find some new ones. No problem.

    If I'm in the upper range, my jakes on unless conditions say "don't do that".
  9. supersnackbar

    supersnackbar Road Train Member

    Aug 19, 2007
    Your Town, USA
    My 2021 Freightliner with an auto transmission burps the jake to shift quicker. All a jake is, is a compression release. If a salesman said that to me, I'd laugh in his face, then walk out and find a reputable dealer to do business with, because he obviously doesn't know his ### from a hole in the ground.
  10. AModelCat

    AModelCat Road Train Member

    Jul 7, 2015
    Lmfao definitely on something.

    All the jake does is open the exhaust valve when the piston is approaching TDC. The old Series 60's used the injector lobe on the cam to run the jake, newer engines (like the ISX I believe) have a dedicated jake lobe on the cam.

    Basically when the jake is on, the pistons compress the air in the cylinders during the compression stroke. Right now the compressed air is acting against the piston travel. Now instead of injecting fuel to make an explosion, the slave piston opens the exhaust valve dumping the compressed air. Now there is no compressed air left in the cylinder to help force the piston down after TDC.

    In a nutshell, the basic operation of the engine has not changed other than compressed air being released from the cylinder.

    As for damage, it ain't gone happen. I've been on hills where literally its a 3rd gear, 3rd stage jake for 20 minutes straight. Nothing blew up or wore out.
  11. Milr72

    Milr72 Medium Load Member

    Dec 16, 2011
    S W Missouri
    I read several years ago where one of the execs from one of the fifth wheel manufacturers said that using a Jake brake will wear out the jaws of a fifth wheel faster than a non Jake equipped truck. I think he was smoking some of the same stuff the salesman was!
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