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  1. #1
    ou812's Avatar
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    Too much Piston Slop?

    This is a buddy's 4tec. It's been rebuilt a few yrs ago by someone else and it's been spitting 90% oil mixture in the catch can and it knocks quite a bit louder than it should. I pulled the head and found the the #1 & #2 cyls are scored on the 4 sides. the piston edge actually slaps the cyl wall by hand.. I haven't looked at #3 cyl yet.

    Here's a video of the slop.. Time for 1st over?




  2. #2
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    wow

  3. #3
    formerly Gold06RXP Turbo Nick's Avatar
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    Thats normal to be able to rock the top of the piston back and forth in the bore. The lower part of th skirt is where the clearence is measered. Your just rocking it back and forth as it rides on the rings between the ring lands of the piston which you can do on a brand new engine like you did. The only way to know if theres excesive ware is to measure the bore and then the piston to find the clearence. Should have done a leak down test or compression check befor removing head to determine health of rings and cylinder walls if you have excessive blow by

  4. #4
    ou812's Avatar
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    Leak down was good with the cheesy harbor freight tester, compression was 1-2-3 140-122-136. There cyls are scuffed at each pin side & both intake & exhaust sides.. I've never seen the top edge of the piston be able to touch the wall before. There's no clearance at all when rocking the piston top edge to the wall.. It's hard to see in the video but it butt's up against the wall.. So this is normal?

    Quote Originally Posted by GOLD06RXP View Post
    Thats normal to be able to rock the top of the piston back and forth in the bore. The lower part of th skirt is where the clearence is measered. Your just rocking it back and forth as it rides on the rings between the ring lands of the piston which you can do on a brand new engine like you did. The only way to know if theres excesive ware is to measure the bore and then the piston to find the clearence. Should have done a leak down test or compression check befor removing head to determine health of rings and cylinder walls if you have excessive blow by

  5. #5
    formerly Gold06RXP Turbo Nick's Avatar
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    The movement is normal

  6. #6
    ou812's Avatar
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    So being the compression & leak down what they are, which is good, and the play is normal, what the hell caused the scuffing and the engine knock?

    Hmm.. I don't want to tear it down if I don't have to but i'm leaning towards doing it..

  7. #7
    Olomana's Avatar
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    Detonation!
    What piston are those? FORGE OEM? or Aftermarket one?

  8. #8
    ou812's Avatar
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    edges are sharp, no sign of deto. OEM pistons and look good. #2 piston actually makes a thud sound when I rock it. The others don't. #3 doesn't move as much but it does rock a little which I know is normal. I just think the other 2 are excessive.

  9. #9
    When the engine was rebuilt, was it bored, did you put oversize pistons in it?

  10. #10
    monaroman76's Avatar
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    Jim, I am no expert, but that sure looks excessive to me. I'm sure I remember my pistons rocking much less than that in my bores. My engine had 120 hours last time I had the head off.

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