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Leak down test results suspicious....need input.

Discussion in 'Road Side Pub' started by Need 04 Wine, Feb 21, 2015.

  1. Need 04 Wine

    Need 04 Wine Meanest CDN on SVTP Established Member

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    So I just did a leak down test on a motor I was going to swap into my car.
    I followed the directions of a Haynes manual to do it.
    #1 at TDC on the compression stroke
    And started test.
    Began at 50psi
    Moved to each different cylinder within firing order and placing each cylinder at TDC

    The results. EVERY single cylinder the intake valve is leaking.
    I can feel the air coming out of the intake port on every single cylinder tested.

    I tried rotating the #8 cylinder only a full cycle and there was no change intake leaked all the way threw.

    What is going on here?
    Iam I missing a crucial step?
    Is it even possible that every single intake valve has a leak?

    Help is much appreciated gentleman.

    Thx
     
  2. ibleedblue65

    ibleedblue65 Active Member Established Member

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    Depends on how big of a leak. If its huge, as in the cylinders are holding no pressure you either don't have the cylinder at tdc on compression or it bent every intake valve.
     
  3. tallfreak

    tallfreak Just a newb Established Member

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    Where did the engine come from? Was the intake manifold already off of it? Were you using a leak down tester or just a compressor and hose? Can you post pics of the back of the valves/in the ports?
     
  4. Need 04 Wine

    Need 04 Wine Meanest CDN on SVTP Established Member

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    Cant get any pressure to hold in cylinder it is immediate bleed off.

    I figure I have it at TDC as 360* turn from this, both lobes on the cams are semi-pointing in towards cylinder

    How would the motor bend every intake valve? cams and chains are hooked up and original
     
  5. Need 04 Wine

    Need 04 Wine Meanest CDN on SVTP Established Member

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    Junkyard

    No I just took manifold off today

    I have modified my compression tester to allow air to go into the cylinder while having a regulator on compressor set @ 50psi, and the compression testers gauge in place.

    As far as pics go, Im not capable of that on this site.
     
  6. Torch10th

    Torch10th I make hits Established Member

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    Have you checked cam timing? To have every cylinder bleed off the intake immediately you've got a cam timing event in the wrong place, or you're not at tdc on the compression stroke.

    How are you locating tdc?

    You didn't specifically say, but I'm assuming this is a mod motor?
     
  7. 03cobra#694

    03cobra#694 I Have LL’s Hammer Staff Member Super Moderator

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    What engine OP?
     
  8. tallfreak

    tallfreak Just a newb Established Member

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    Your test isn't telling you much. Go to autozone and rent a real leakdown tester. It will tell you how much leakdown you have in percentage. No engine holds air 100%. It shouldn't be coming out of the valves though. I would suspect the back of the valves are a little dirty or even have some surface rust. See if autozone has a bore scope so you can look down in the cylinders and you should be able to get a good look at the valve seat. A single grain of sand will cause a massive valve leak.

    Junkyard engines in my experience aren't out of time. It's usually a running engine that was totaled. Have you seen the car it came out of?
     
  9. Need 04 Wine

    Need 04 Wine Meanest CDN on SVTP Established Member

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    I don't have a degree wheel.

    Locating TDC as follows. Working on #1 cylinder, turn crank pulley to align TDC mark with notch on pulley. Made sure cam lobes were "pointed" away from cylinder head( to me this would be the most closed on both valves)
    Then follow firing order and rotate crank 90* to move to next cylinder in firing order
    Yes 5.4L 2V 2003 Modular

    thx
     
    Last edited: Feb 22, 2015
  10. Need 04 Wine

    Need 04 Wine Meanest CDN on SVTP Established Member

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    5.4 L 2V 2003

    thx
     
  11. Need 04 Wine

    Need 04 Wine Meanest CDN on SVTP Established Member

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    This actual makes a lot of sense as when I would put air to it some of the ports had debris lift out of them.

    Negative didn't get to lay eyes on the donor vehicle.

    So I suppose my next course of action would be....Pull cams, heads, and remove valves for inspection of seat and valve?

    Im trying to do this threw forums and my ambition for expanding my hobby knowledge.... so if I have to keep pulling it apart it will only further my understanding.

    Thx guys good info here
     
  12. RonMexico

    RonMexico New Member

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  13. Need 04 Wine

    Need 04 Wine Meanest CDN on SVTP Established Member

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    Yes that would be very nice, However it costs 1/3 of what the motor did.

    So the way I have my set-up I do have three gauges. One for bottle pressure, one for regulated input pressure, and one at the cylinder for actual pressure in chamber.

    Im curious how the percentage works. I know Im putting in 50 psi, some cylinders hold no pressure at all and a few hold the cylinder gauge at around 10psi.

    Apparently my thoughts on Leak down test were way off, kinda thought of it like a balloon, fill it with air if it holds perfect, if it slowly leaks out not perfect.
     
  14. tallfreak

    tallfreak Just a newb Established Member

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    I have a matco leakdown tester. It tells you the percentage of leak. It has one gauge for pressure and one for percentage. I think the percentage gauge is just the pressure in the cylinder.

    You have to pull the heads to remove the valves. Since you have the valve covers off, verify the engine is still in time. Go get a real leakdown tester and bore scope. It sounds like your test is similar to a real tester but you don't know what your results mean. If you can't read the results the test is invalid.

    Cylinders are not like a balloon at all. The rings will leak a little no matter how new or old or clean the engine is. The valves should have no leaks. A general rule of thumb is 20% leakage or less. Preferably 10% or less. When I am testing an engine I know hasn't been run in a while I will accept a little higher number than an engine that drove into the shop. The cylinders on a engine that hasn't been running will have no oil.

    Spray some brake clean on the back of the intake valves when they are closed then again open. Blow the ports out with air. Try to get all the trash out you can.

    Do you know how many miles are on it?
     
    Last edited: Feb 22, 2015
  15. Need 04 Wine

    Need 04 Wine Meanest CDN on SVTP Established Member

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    Ya ill definitely work at getting the back side of those valves cleaned up and blown down best I can.
    Trying to avoid spending additional money on a tool honestly probably use once, but may have too yet

    Sold as a 75000km engine.
     
  16. tallfreak

    tallfreak Just a newb Established Member

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    I don't know about stores around you, but all the auto parts stores rent tools. No need to buy it.
     
  17. Need 04 Wine

    Need 04 Wine Meanest CDN on SVTP Established Member

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    Ill have to check in City reasonably sure it is not a thing around here.
    Will be next week by the time I get around to it though

    Ill post back when I have some more info
     
  18. pur octane

    pur octane Member Established Member

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    don t know where in Canada you are,but part source has blow down gauge and bore scope also
     

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