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855 cummins jake brake swap

Discussion in 'Trucks [ Eighteen Wheelers ]' started by Leadfoot758, Dec 9, 2015.

  1. Dec 9, 2015 #1
    Leadfoot758

    Leadfoot758 Bobtail Member

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    Dec 9, 2015
    0
    I have two old freightliners, one of which i use for a month out of the year during harvest season, and the other i use for parts. Both have the cummins 855 big cam 4 engines. the parts truck has the jake brake, the truck I use does not. I've been playing around with the idea of swapping the jake to the truck I use. Although I'm fairly handy when it comes to wrenching, I have really no idea how the jake brake works, other than it has to do with the heads and valves. So, to you trucking veterans out there, is this something I can do in my dirt floor pole shed using my basic tools without causing it to go KABOOM? (she's all I have to get my corn to the elevator). And if I can, will I need anything like new gaskets, O-rings etc..? Thanks for your input!
     
    Leadfoot758, Dec 9, 2015
    Leadfoot758, Dec 9, 2015
    #1
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  3. Dec 9, 2015 #2
    Inland-Pilot

    Inland-Pilot Light Load Member

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    Jun 23, 2010
    Jackson, Ms
    0
    You can do this in the barn. You'll need the wiring harnesses, switches, the rocker boxes, the rocker box studs, the wider exhaust valve cross heads and jakes off the donor. New rocker box and jake gaskets. That's about it. The plastic valve cover gaskets are reusable. If you have cork valve cover gaskets, replace those. That's basically it for NTC, if you have STC, it's a little more involved. You can google how to reset/adjust the overhead. It's a pretty simple job, just takes a little time.
     
    Inland-Pilot, Dec 9, 2015
    Inland-Pilot, Dec 9, 2015
    #2
  4. Dec 9, 2015 #3
    BoxCarKidd

    BoxCarKidd Road Train Member

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    Aug 26, 2014
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    I have put heads on a 8V92 in a pole barn like that so it is possible but I do not know if you can do that. I suggest replacing the rocker box, valve cover gaskets, and rocker shaft o-rings. You do not have to know how it works but use the rocker boxes from the jake brake engine. The BC4 could have jake, C, or tec brakes and the gaskets are not all the same, watch for that. It is not a bad idea to set the engine up on timing marks, know where it is at, and everything is OK before you take it apart. I back all the injector set screws off 1 turn before disasembly so I do not have to worry about damaging injectors or cam. Requires a double deep 5/8 socket.
    Pilots correct: Jakes and tec's also have 3 o-rings for the oil.
     
    Last edited: Dec 9, 2015
    BoxCarKidd, Dec 9, 2015
    BoxCarKidd, Dec 9, 2015
    #3
  5. Dec 9, 2015 #4
    Leadfoot758

    Leadfoot758 Bobtail Member

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    Dec 9, 2015
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    Sounds fairly simple, starting to think I may be able to tackle this. I'm guessing once I get them both apart I'll notice what's different and it'll make more sense to me. My one concern now is how to I know if it's ntc or stc? This is the first time I've heard of this. And also, pilot, you mentioned I can use the rocker boxes off the donor, but then also added that I should put on a new rocker box? Please be patient with me, I know just the basics, I'm just guessing the rocker box is the rocker arms?
     
    Leadfoot758, Dec 9, 2015
    Leadfoot758, Dec 9, 2015
    #4
  7. Dec 9, 2015 #5
    BoxCarKidd

    BoxCarKidd Road Train Member

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    Rocker boxes are the same except the allen set screw in the middle has a hole in it to supply oil to the jakes.
     
    BoxCarKidd, Dec 9, 2015
    BoxCarKidd, Dec 9, 2015
    #5
  8. Apr 29, 2023 #6
    nightcrawler1

    nightcrawler1 Bobtail Member

    1
    0
    May 16, 2020
    0
    how did the swap go....im about to put jakes on my ntc-350
     
    nightcrawler1, Apr 29, 2023
    nightcrawler1, Apr 29, 2023
    #6
  9. Apr 29, 2023 #7
    BoxCarKidd

    BoxCarKidd Road Train Member

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    Aug 26, 2014
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    I suppose that question is for Leadfoot758 but he has never been back since 2015.
    The Tech brake worked fine for me.
     
    BoxCarKidd, Apr 29, 2023
    BoxCarKidd, Apr 29, 2023
    #7
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