Cat 3406e Weak Engine Brake

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Rangler102000, Mar 29, 2022.

  1. Rangler102000

    Rangler102000 Bobtail Member

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    I have a Cat 3406e (Serial# 5EK61336) that has a weak engine brake. I just had an overhead done, installed 3 new solenoids, installed new wiring harness for injectors and engine brakes. The truck makes the noise in all 3 switch positions, but engine brake is still very weak. The manifold pressure while engaged going down a hill doesn’t go over 15 psi. Any help would be much appreciated.
     
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  3. kranky1

    kranky1 Road Train Member

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    I think they may have mis-set the brake lashes. Those engines had 2 different brakes. Jacobs and Pac Brake, there are a couple of different models of each, and the lashes are different.
     
  4. Mike250rs

    Mike250rs Heavy Load Member

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    I've had set screws back out of some of the Jacobs in the past.
    That should have been checked during overhead though.
     
  5. kranky1

    kranky1 Road Train Member

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    He may have mis-set them. Just on the Jake’s there’s 3 different models with about .005” difference in lash between them. That’s enough to affect brake performance. Pac Brakes are all .028 I think, mine are, but I’m pretty sure all 3 Jacobs models are different. Might be the problem. I’ve had expectation problems with brakes on Cats too. Until the Pac Brake for the 3406B showed up a brake on a Cat did you about as much good as sticking your hat out the window. Pac Brakes are a bit better, but If you’re expecting that brake to dig in and hold like a Detroit or Cummins would you’re going to be disappointed.
     
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  6. Big Road Skateboard

    Big Road Skateboard Road Train Member

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    Are you comparing the efficiency of the brake to a newer truck? Or have you driven other E models that did better?
     
  7. lester

    lester Midwest's #1 Feed Hauler

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    15 psi is about all I get out of my slightly larger than stock single turbo cat.

    Check for boost leaks
     
  8. Coffey

    Coffey Heavy Load Member

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    Screenshot_20220329-211742_Drive.jpg
    I just looked it up on jacob website it says for 410 and under hp is .027 and 435 and over is .030
     
  9. Last Call

    Last Call Road Train Member

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    Cat Jake's are just like a couple women I've dated ..
    They make alot of noise like their doing something
    But when it's all said & done their performance leaves you disappointed
    That's the reason I run a Brake Saver
     
  10. kranky1

    kranky1 Road Train Member

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    When I ordered my ‘89 I was living in B.C. I ordered a Brakesaver engine and put a Pac Brake on it when I got it. That ####er will put you right against the windshield.
     
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  11. kranky1

    kranky1 Road Train Member

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    Well that’s all good. What are the ones under your valve covers? All I was saying was they could have been set to the wrong spec, or just wrong. It happens. Those kids you see running around in shops now with their surgical gloves and earphones on couldn’t find their own ### with both hands and a flashlight.
     
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