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    #1

    leaking intake valve BUT...

    pulled the head and springs, pushrod, piston, and valve all look good! I just dont get it, but i know that that intake valve leaked really bad.

    The only thing i could think of it being is a lifter plunger stuck all the way out not allowing the valve to close all the way during operation.

    Your ideas would be much appreciated because the i took the motor apart down to and including the head today and would like to get it back on the road by the end of the week.

    thanks, andy
    Finally have an on the books porting/custom fab business!
    HO bottom end,GT40Ps,cut/welded/ported upper+lower GT40 intakes,Comp XE258 cam,MS3X megasquirt computer,8 LS2 coils,2 dry systems + a 3rd wet,3 core rad w fans..1100hp Lentech WR AOD,custom 4" aluminum/moly Dshaft,custom rear/back half chassis adjustable 4link,wilwood 4 piston,moser 9" axles,locker, M/T 30x12's,4 staged fuel pumps,100lbs sound insulation,power/remote everything,2000W sound.4480lbs. 4.5s 0-60,12.8 1/4

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    #2
    Take the valve out, and roll the stem across a flat surface. It may not look bent, but it may be.

    Did you look at the lifters? Do they look ok?
    **2012 Ford Mustang Boss 302: 5.0/ 6 spd/ 3.73s, 20K Cruiser
    **2006 MGM,"Ultimate": 4.6/ 2.73/ Dark Tint, Magnaflows, 19s, 115K Daily Driver
    **2012 Harley Davidson Wide Glide (FXDWG):103/ Cobra Speedsters/ Cosmetics, 9K Poseur HD Rider
    **1976 Ford F-150 4WD: 360, 4 spd, 3.50s, factory A/C, 4" lift, Bilsteins, US Indy Mags, 35s Truck Duties

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      #3
      eliminate anything beyond the valve stem in the valvetrain by running the compression test again without the rocker bolted down. Obviously if you still have a leak it's not a lifter.

      85 4 door 351 Civi Crown Victoria - Summer daily driver, sleeper in the making, and wildly inappropriate autocross machine
      160KMs 600cfm holley, shorty headers, 2.5" catted exhaust, 255/295 tires, cop shocks, cop swaybars, underdrive pulley, 2.73L gears.
      waiting for install: 3.27's, Poly bushings, boxed rear arms, 2500 stall converter, ported e7's, etc

      06 Mazda 3 hatch 2.3L 5AT (winter beater that cost more than my summer car)

      Comment

        #4
        the old trick was to position the head so the gasket surface is facing up. Put trans fluid in the combustion chamber and let it sit. If you see it leak into the intake or exhaust port, then the valve is not sealing for whatever reason. Could put some machinists blue on it and push it into the seat. If its not making a good seal, you'll see spots where the blue doesn't transfer to the seat. If things are right, you'll have an even line of blue marking all the way around.
        86 Lincoln Town Car (Galactica).
        5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

        91 Lincoln Mark VII LSC grandpa spec white and cranberry

        1984 Lincoln Continental TurboDiesel - rolls coal

        Originally posted by phayzer5
        I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

        Comment

          #5
          did that with carb cleaner filled up in the combustion chamber and no leaks. It all looks fine on the head wise, so it must have to be my lifter plunger is stuck all the way open... that is all that i can think of. Because 150psi on all cylinders then like 3psi on that one, and the leakdown was pushing air out that valve as fast as it could supply air, so the leak is huge.

          I don't know, it doesn't seem to likely that the plunger would stick all the way open, but its the only thing i can think of.
          Finally have an on the books porting/custom fab business!
          HO bottom end,GT40Ps,cut/welded/ported upper+lower GT40 intakes,Comp XE258 cam,MS3X megasquirt computer,8 LS2 coils,2 dry systems + a 3rd wet,3 core rad w fans..1100hp Lentech WR AOD,custom 4" aluminum/moly Dshaft,custom rear/back half chassis adjustable 4link,wilwood 4 piston,moser 9" axles,locker, M/T 30x12's,4 staged fuel pumps,100lbs sound insulation,power/remote everything,2000W sound.4480lbs. 4.5s 0-60,12.8 1/4

          Comment

            #6
            Did you do the compression test more than once? Could a valve have been sticking open? Are your valve seats recessed any? With the head assembled lay a straight edge across the tips or measure and make sure they are all uniform height.

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