Tell Tale Signs that Piston Rings are Bad?

Posted by neghsmoke, Apr 21, 2005
Newbie Forum - Beginner/newbie/general DSM modification questions. First mods, how to run 10's when you haven't run 12's yet, any tech question that doesn't fit in another tech forum.

  1. neghsmoke

    neghsmoke Proven Member

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    Olney, Illinois
    I've already got the head off and am unable to do a leakdown test, so are there any tell tale signs that the piston rings are or could be going bad?
    #1
  2. FunkMasterChipZ

    FunkMasterChipZ Proven Member

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    rochester, New_York
    just replace 'em best idea ever...... :thumb:
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  3. Game Over

    Game Over Proven Member

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    Was the car smoking when it was running?

    If you already have it torn apart, just replace them, it's worth the extra cash.
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  4. neghsmoke

    neghsmoke Proven Member

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    Olney, Illinois
    I've got the head off already. I'm only starting to get into internal engine work, so i'm not sure exactly what the process for replacing rings is. Does the block need to be bored or honed? I really didn't want to pull the engine entirely from this car.

    Also, the car was never running. It had about 30psi in each cylinder (give or take 10-20PSI) cranked fine but of course it wouldn't start.

    I've got the head at a machine shop right now to see if it's warped and get it resurfaced (if it's not warped) Hopefully he will check the valves while he's at it.
    #4
  5. WadexTSi

    WadexTSi Proven Member

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    Detroit, Michigan
    It might be worth just replacing them now. If I was rebuilding a dead engine thatb I didnt know the history behine, Id definitely check out those rings.
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  6. neghsmoke

    neghsmoke Proven Member

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    Olney, Illinois
    So the rings can be replaced without doing any machining work on the block?
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  7. psychlow

    psychlow Proven Member

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    Colorado Springs, Colorado
    It depends.

    The bores have to be measured. If they are too far out of round, you'll have to overbore them and get new rings and pistons to fit the larger bore.

    If they're not out of round, you can just rehone the cylinders and slap on a new set of rings.

    The cylinder bores must be rehoned to put a crosshatch pattern on the walls. If this step is skipped, your engine will smoke like a chimney until the rings seat, assuming that they ever do.
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  8. neghsmoke

    neghsmoke Proven Member

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    Olney, Illinois
    I don't have the time or knowledge to remove the entire block, strip it, and take it to a machine shop right now. I'd rather just install a remanufcatured head and hope I can get it running reliably with low boost.
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  9. sonicnofadz

    sonicnofadz Proven Member

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    Baltimore, Maryland
    Despite what some of these people might suggest to you, you *SHOULD NOT* remove the pistons from the block and just replace the rings. If you pull the pistons your going to have to at least remove the crank and all the bearings associated with that, so you might as well replace all the crank bearings, but new ones cannot be fitted without precise measurement by a machine shop (plastigauge in my opinion does not cut it). Also, as mentioned above, you don't know how worn down your cylinder walls are, so the size of the new rings cannot be determined (usually) without taking the block to a machine shop. I am assuming you do not have the cash for a REAL rebuild, so your best bet is to slap everything back together like you were planning on doing and do a compression test (and hope everything is OK). If it isn't ok, then you just wasted a whole lot a time (and maybe some money on the gaskets) instead of a whole lot of money wasted on a improper rebuild (an improper rebuild defined as replacing JUST the rings).
    #9
  10. armandovivoni

    armandovivoni Proven Member

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    sanjuan, South_America
    what I did. i bought the piston rings from mopar. and replaced the rod bearings. and everything is fine. you dont have to remove the engine. just remove the crank. the rods. and pull the pistons from the top. the bearings have the size marked on them. just go buy the same size bearings and put them on.
    #10

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