Mack Jake brake

Discussion in 'Trucks [ Eighteen Wheelers ]' started by freebirdrfd, Nov 10, 2011.

  1. freebirdrfd

    freebirdrfd Light Load Member

    Thanks Received:
    Oct 8, 2011
    Raynham Ma
    I drive a 2000 vision, the Jake seems to only work when the truck is NOT up to operating temperature. When I first start the truck it seems to work fine, but as the temperature gets up to around 180 it doesn't work. I can hear a clicking noise when the Jake should be coming on. If I touch the clutch or shut the Jake switch off the clicking stops. Both wires going to the engine seem to have a good connection. One other thing that I knoticed is that when it is working, it works the same in both low stage and high stage. Does anybody know what the problem could be?
  2. power freak

    power freak Light Load Member

    Thanks Received:
    Apr 23, 2009
    I would say the problem with your Jake brake is insufficient oil pressure to the Jake heads caused by worn cam bearings. Your jakes will work when the engine is cold because of the thicker oil when cold but as the engine warms up the oil thins out and escapes around the worn cam bearings and does not supply enough pressure to the Jake heads for them to function correctly. There are two ways to remedy your problem one is to pull the cam and replace the bearings two is to buy the updated Jake heads with the external oil feed to them that runs through the Jake spacer and tees into the turbo feed port on the oil cooler. Also make sure you have the latest update in the Jake heads they had many design changes over the first years of the e-tech but I would imagine by now they would have all been done.
    freebirdrfd Thanks this.