2000 mack e7 460 jake brake problem

Discussion in 'Trucks [ Eighteen Wheelers ]' started by Ezrider_48501, Oct 31, 2014.

  1. Ezrider_48501

    Ezrider_48501 Road Train Member

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    on the truck i recently purchased has very for jake braking performance. i have found that only the front 3 cyl jakes are functioning.

    i found this by first unplugging the pass threw connector on the rear head witch made no change in the Jake brake performance, i then plug the rear pass threw connector back in and unplugged the front and then had no jake brake. what is the best way to figure out if the problem is before the pass threw connector or under the valve cover?
     
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  3. Pablo-UA

    Pablo-UA Road Train Member

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    what ECM? Bosch M6? Any fault codes?

    Usually bad solenoid, sometimes bad wiring on rear end of engine.
     
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  4. Ezrider_48501

    Ezrider_48501 Road Train Member

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    if i run a jumper wire from the front head to the pass threw on the rear head will it hurt anything. just to see if the problem lies before that point or after.

    im thinking solenoid as well but it could be somthing as simple as a bad switch. never had any jake problems with a truck before let alone messed with a mack so this is new territory for me...lol
     
  5. asavage1576

    asavage1576 Light Load Member

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    Kind of off topic ezrider. From your new pic I'm guessing you bought that mack. Nice truck
     
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  6. Pablo-UA

    Pablo-UA Road Train Member

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    really ECM output has current sensor. not sure, but may get short circuit fault code.

    In 24 v trucks it works, not sure about 12v trucks.

    Ok, before u do it, check wires and solenoids with DVOM. May be electrical parts are ok,and just valve is stuck
     
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  7. Ezrider_48501

    Ezrider_48501 Road Train Member

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    ok so iv done more reading on jake brakes over the last few days than i care to think about (never had a faulty Jake before so never learned much about them) of course that's the upside now i get to learn about them.

    according to a pdf i found online and a cheap ### ###### analog volt meater and a peice of wire (haven't made it home to my shop yet so i was messing with it in a truck stop parking lot and don't have a whole lot of tools with me.

    from reading the pdf (witch i think is actually for 2003+ mack motors)
    i should have a low amp 12v at all times on both jakes and when the jakes activate it is suppose to up the current to energize the solenoid. now i cant actually acitave the jake from under the hood but i found closer to 6 volts on both leads for the pass threw. (front jake works both got the same reading so should be fine and its literally like a 5 dollar analog volt meter) so this would indicate to me that the wireing prior to the pass threw is not suspect)

    so now after that i got a little more gutsy and increased the idle rpm to 1000 unplugged both pass thews and used a peice of wire to jump the pass threw. front activated the jake. the rear did not.

    now we get real technical both pass threw connectors gave off about the same small arch when touching my hot wire too them, (not a dead short arch just a small visible spark like you would expect on a 1-2amp draw. this would indicate to me that the wiring from the pass threw to the solenoid is good.

    obviously im not going to tear the valve cover off in a truck stop parking lot so that is going to have to wait till i get home. but would you think it would be a safe enough bet that the solenoid is the problem to call up mack at home and order up a Jake solenoid and have the wife go pick it up so its there waiting for me when i get home. (might not make it home till next weekend and mack is only open m-f)
     
  8. Pablo-UA

    Pablo-UA Road Train Member

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    sometimes cleaning it with solvent helps. I had this problem yesterday with Volvo D12A engine. I drop valve in jet fuel for a hour, now it works
     
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  9. Ezrider_48501

    Ezrider_48501 Road Train Member

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    mack called me to tell me that some other parts i had ordered had come in, while i was on the phone with them i had them pull a jake break solenoid and put it in with my order it was $181 for the solenoid. hopefully that is my problem.

    if it is the problem ill try cleaning the old one and if that fixes the old one ill keep it as a spare.
     
  10. Ezrider_48501

    Ezrider_48501 Road Train Member

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    well i finnally made it home and got to check things out, i found that one of the freeze plug like plugs in the end of the rocker shaft had come out, found the plug in the bottom of the rocker valley.



    i had no luck finding a new one on sunday and have to get heading back out so i just re-installed the old plug, would have rather not done that but put a little bit of loctite on it and re-installed it, the jake works now, i guess if it stops working again ill have to call mack and get a new plug.
     
  11. Cat sdp

    Cat sdp . .

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    Off topic.......

    Are you running both trucks , or dumping the old one?
     
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