Leak Down Procedure (Pic Heavy)

  1. seabee
    Did a leak down test on the 273 today and took some pics on how I did it for the next guy that searches it. Please add any , corrections, advice, or tips.

    1. Find Top Dead Center on Piston #1. I used a piston stop to make sure the balancer hadn't shifted.


    Using a small level I made horizontal and vertical marks:


    Each 1/4 turn of the crank will put the next cylinder in the firing order at top dead center. Firing Order: 1 8 4 3 6 5 7 2


    Next I checked the gap (solid, non hydraulic lifters) to make sure the valves were fully closed. I could also just remove the rocker arms completely.

    Then I used the piston stop on the cylinder opposite the firing order to prevent the crank from turning under the air pressure. Opposite pistons: 1:6, 2:3, 4:7, 5:8

    Then Applied 100PSI to get the first reading. Number 8 cylinder is losing 20%.

    Then I put the spark plugs into the neighboring cylinders to help rule out a head gasket breach between cylinders.

    Next I use a piece of hose to my ear and listen to locate where the 20% of air is going to.
    Carb: Intake Valve
    Exhaust:Exhaust Valve
    Dip Stick (Crankcase): Past the piston rings (Normal)
    Radiator: Cracked head or cylinder wall.

    I wrote down all the results:

    Might be time for a rebuild, what do you think?

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