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N-Trouble's avatar
N-Trouble
Explorer
Jun 16, 2015

Duramax boost leak?

I believe I have a boost leak on my truck and pressure tested the system recently up to 30PSI. Looking for any feedback on whether this looks like a boost leak or is normal engine leakdown? Seems excessive to me to be normal leakdown on a non-overlap motor such as the Duramax. I can hear what sounds like air rushing out of the system in the area around the EGR cooler or Y-bridge. No leaks found on any of the intercooler up/down pipes.

Truck is a 2012 and gets pretty poor mileage, regens every ~200mi and feels gutless at high altitude 7-8k ft. Have to floor it just to hold 50-55MPH pulling hills with an 10-11k lb 5er.

https://www.youtube.com/watch?v=ycfQ4IzFJxk
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9 Replies

  • N-Trouble's avatar
    N-Trouble
    Explorer
    Jun 18, 2015
    Exactly, an open or leaking EGR IS a source of a possible boost leak. I'm not trying to perform an "engine" leak down.
  • Turtle_n_Peeps's avatar
    Turtle_n_Peeps
    Explorer
    Jun 17, 2015
    N-Trouble wrote:
    rhagfo wrote:
    Turtle n Peeps wrote:
    I'm still trying to figure out what you're doing?

    How did you block off the turbo and intake manifold to check for the leak because that's the only way I know of to check for a boost leak? :h


    X2


    This: https://www.youtube.com/watch?v=x5XoOe3Zjuo

    There is nothing to block off. Test is done post turbo. YOur just simulating the turbo with compressed air.


    Got ya.
    I see what you're doing now. Kind of a weird and crude way to leak down an engine but I guess it works.

    Only problem is if the EGR valve is open or leaks it will give you a false reading. It will just run from the intake through the EGR valve and out the exhaust.

    Anyway, to answer your question: I don't like a new broken in engine to leak down more than 2%. A well used engine I don't like to see more than 7%.
  • christopherglen's avatar
    christopherglen
    Explorer
    Jun 17, 2015
    You are disconnecting the silicone coupler from the turbo, putting a plug with an air supply in its place, and charging to 10-20 psi. This will test all but the turbo to coupler connection.
  • N-Trouble's avatar
    N-Trouble
    Explorer
    Jun 17, 2015
    rhagfo wrote:
    Turtle n Peeps wrote:
    I'm still trying to figure out what you're doing?

    How did you block off the turbo and intake manifold to check for the leak because that's the only way I know of to check for a boost leak? :h


    X2


    This: https://www.youtube.com/watch?v=x5XoOe3Zjuo

    There is nothing to block off. Test is done post turbo. YOur just simulating the turbo with compressed air.
  • ACZL's avatar
    ACZL
    Explorer
    Jun 17, 2015
    Wooshing sound is most likely a intercooler leak. Had this happen on my '03 Powerstroke. Where it was leaking, dunno, dealer found/fixed it. From what the OP is saying about being gutless, then the turbo has lost it's boost and effectiveness. If it is the intercooler, look into aftermarket ones (ie: Banks Power for example). May cost a tad more, but probly better performance over stock.
  • rhagfo's avatar
    rhagfo
    Explorer III
    Jun 17, 2015
    Turtle n Peeps wrote:
    I'm still trying to figure out what you're doing?

    How did you block off the turbo and intake manifold to check for the leak because that's the only way I know of to check for a boost leak? :h


    X2
  • Turtle_n_Peeps's avatar
    Turtle_n_Peeps
    Explorer
    Jun 17, 2015
    I'm still trying to figure out what you're doing?

    How did you block off the turbo and intake manifold to check for the leak because that's the only way I know of to check for a boost leak? :h
  • Sport45's avatar
    Sport45
    Explorer II
    Jun 17, 2015
    I'd try a couple of things.

    1. Set the air regulator at 20 psi, open the valve and let it hold the manifold pressure there. Go back to the exhaust and see if you can hear any air escaping. Maybe hold some cling wrap over the exhaust to see if it tries to inflate.
    2. Set the regulator at 2-3 psi. Put a healthy squirt of dish soap in a half gallon of water and mix in a pump sprayer. Hose everything down with the soap solution and look for bubbles. If no bubbles are seen hose it down again and slowly raise the pressure until you know it's not holding. Hose it down again.


    The first test will let you know if you're losing air through the engine. Could be a burnt/leaking valve or leaking EGR valve. The second test helps find external leaks. Hose the soap off with fresh water when you're done.
  • ScottG's avatar
    ScottG
    Nomad
    Jun 16, 2015
    It's a really good question.. How much, if any leakage is acceptable? My thought is any leakage is bad but I don't know for sure.
    Looking forward to hearing what people in the know say.

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