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Leakdown and compression results

Posted by bpk1337, May 16, 2017

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  1. bpk1337

    bpk1337 Proven Member

    106
    5
    Joined Oct 28, 2008
    Phoenix, Arizona
    While doing some street tuning near where I live, a T-fitting for my turbo oil feed/oil pressure gauge cracked. The oil dummy light turned on so I drove it home (stupid move I know, but I was only a few blocks away). Sent my 68hta to Justin after finding some in and out shaft play. His findings were, "It's 100% fixable...honestly it doesn't even look like it had any oil starvation as there's no bearing transfer at all on the shaft or housing, just appears the thrust plate failed because they're not using upgraded thrust hardware on these turbos when they're built."

    Installed everything back on and did a leakdown and compression test last night after driving the car around to warm it up. The photos below show my numbers along with my piston info. I rebuilt the motor (6 bolt in a 2g) less than a thousand miles ago.

    What do you guys think? Do I need to pull the motor, rehone, and install new rings or is there something else going on? From what I've read those leakdown numbers are really bad, but the compression looks good. One thing to note though, when I did the compression test is it took many cranks (around 30/ea. cylinder) for the needle to finally stop at 170psi.

    Leakdown_Compression.jpg
    Ross Piston Spec.jpg
     
  2. jakk220

    jakk220 Proven Member

    1,161
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    Joined Nov 13, 2010
    Akron, Ohio
    Did you try to find out where it was leaking to during the leak down test? Like opening the rad cap and seeing if there were bubbles in the coolant or opening the oil cap, dipstick tube, or PCV valve and listening for air?
     

    323  1

    1991 Mitsubishi Eclipse GSX
    awd · manual · 1G DSM

    1K  3

    1997 Mitsubishi Eclipse GSX
    awd · manual · 2G DSM

    Street Build 1K  1

    1993 Mitsubishi Eclipse GSX
    awd · manual · 1G DSM
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  3. bpk1337

    bpk1337 Proven Member

    106
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    Joined Oct 28, 2008
    Phoenix, Arizona
    Yeah, prior to installing the turbo I did a cold leakdown test and some air was coming from the oil cap so I took the valve cover off and it seemed to be coming from the crankcase, but it was hard to tell exactly. Pretty sure it wasn't from the valves seats though.

    When I did the test last night I forgot to check the oil cap :ohdamn:, but I did hear hissing from the dipstick. Just wanted to get a quick run down of the numbers.
     
  4. jakk220

    jakk220 Proven Member

    1,161
    251
    Joined Nov 13, 2010
    Akron, Ohio
    Are you sure the leakdown tester is functioning properly?
     

    323  1

    1991 Mitsubishi Eclipse GSX
    awd · manual · 1G DSM

    1K  3

    1997 Mitsubishi Eclipse GSX
    awd · manual · 2G DSM

    Street Build 1K  1

    1993 Mitsubishi Eclipse GSX
    awd · manual · 1G DSM
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  5. bpk1337

    bpk1337 Proven Member

    106
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    Joined Oct 28, 2008
    Phoenix, Arizona
    Is there a way to confirm that it is operating correctly? It's a Harbor Freight unit.
     
  6. 1990TSIAWDTALON

    1990TSIAWDTALON Moderator

    4,591
    2,020
    Joined Nov 14, 2013
    Independence, Kansas
    I like the compression numbers. Pretty sure the leakdown is best performed warm tho.
     

    Street Build 3K  27

    1992 Eagle Talon TSi AWD
    awd · automatic · 1G DSM

    548  14

    1990 Mitsubishi Eclipse GSX
    awd · manual · 1G DSM

    450  18

    1967 Chevrolet Camaro RS
    rwd · automatic · Misc Vehicles

    Street Build 654  7

    1998 Eagle Talon TSi
    fwd · manual · 2G DSM

    Street Build 5K  11  25

    1990 Eagle Talon TSi AWD
    13.620 @ 108.460 · 1G DSM
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  7. bpk1337

    bpk1337 Proven Member

    106
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    Joined Oct 28, 2008
    Phoenix, Arizona
    The numbers posted the photo were from a warm leakdown test. Sorry if I caused any confusion...
     
  8. SOADweskey

    SOADweskey Proven Member

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    Joined Dec 11, 2006
    Jacksonville, Florida
    My standard number of revolutions for a compression test is 6. If you had to crank it 30 times to get a solid number then I wouldn't trust those compression numbers.
     
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  9. bpk1337

    bpk1337 Proven Member

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    Phoenix, Arizona
    Any ideas as to why it would still give me a consistant 170 all across though?
     
  10. SOADweskey

    SOADweskey Proven Member

    762
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    Joined Dec 11, 2006
    Jacksonville, Florida
    That I'm not sure of, have you ever seen that tester show higher than 170? Total shot in the dark but that could be the highest your gauge will read. If yours is from harbor freight like mine then it wouldn't be unheard of for it to act strange.

    I mean that shouldn't matter because a properly functioning tester won't keep going up the longer you crank it. But it does seem really weird to me that it took that long to stabilize.
     
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  11. bpk1337

    bpk1337 Proven Member

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  12. diambo4life

    diambo4life Proven Member

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    Edmond, Oklahoma
    No way those leakdown numbers are real if it was done correctly. I recommend removing the cams and repeating the leakdown.
     

    Drag Race Build 623  1

    1990 Mitsubishi Eclipse GSX
    manual · 1G DSM

    Street Build 4K  25

    1991 Mitsubishi Galant VR-4
    710 whp · 501 lb/ft · Galant VR-4
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    gsxeclipse102 likes this.
  13. bpk1337

    bpk1337 Proven Member

    106
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    Joined Oct 28, 2008
    Phoenix, Arizona
    Noticed that the car is burning some oil on WOT drives.
     

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