Bent valves?how can I tell

Posted by 90tsiawdturbo, May 25, 2010

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  1. 90tsiawdturbo

    90tsiawdturbo Proven Member

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    Is there a way I can tell if my valves are bent with out taking my head off...I kno one piston and/or rings are bad but I still gotta be able to possibly drive it 15 miles to the shop so I don't want to take the head off... Any suggestions?
     

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  2. Derock2gspyder

    Derock2gspyder Proven Member

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    compression test! check the compression and see a bent valve will leave the compression very low or at 0!
     
  3. 90tsiawdturbo

    90tsiawdturbo Proven Member

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    Like I said I have a bad piston so I know there's bad compression in that cylinder....is there any other way?
     
  4. woomer

    woomer Proven Member

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    just about every time you bend a valve - even if your saying your pistons are bad - it still should have compression even if its low ------ with a bent valve you will have zero compression --------a compression check is basicly the only way of telling short of pulling the head and getting a shop to check it - zero compression is a sure tell sign of a bent valve :nono:also if you have a very severe miss ....even at idle --and loss of power --- but run a compression check sure fire way
     
    Last edited: May 26, 2010
  5. DeadsEvolution1

    DeadsEvolution1 Proven Member

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    I agree, you need to run a compression test. If you do infact have a bent valve the cylinder should be at 0 compression when testing. Read the Vfaq if you do not know how to do the test.
     
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  6. donniekak

    donniekak DSM Wiseman

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    Pull the valve cover and look for loose rocker arms. Do a leakdown test.
     
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  7. 90tsiawdturbo

    90tsiawdturbo Proven Member

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    Ok thank you guys very much for the help I appreciate it a lot!!
     
  8. spoolin ddub

    spoolin ddub Proven Member

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    A compression test is good but it just shows that a problem exists. Do a leak down test so you can pinpoint the exact source of the compression loss. You say one piston and/or ring is bad. You may have more than one problem. You could have 0 compression from a bent intake and/or exhaust valve and then on top of that have a bad ring in that same cylinder. A compression test won't pinpoint that. It's best to do both test.
     
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  9. 90tsiawdturbo

    90tsiawdturbo Proven Member

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    Well I'm showing low compression in that cylinder not zero compression
     
  10. BogusSVO

    BogusSVO Proven Member

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  11. spoolin ddub

    spoolin ddub Proven Member

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    The only way to know for certain what it wrong is to do a leak down test.
     
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    1990 Eagle Talon TSi AWD

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  12. JusMX141

    JusMX141 Moderator

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    Pull the valve cover. If any of the lifters seem to be out further than normal, or if any of the rockers are loose you have bent valves on that cylinder.

    100_0986.jpg


    But again, if you have obscenely low compression on any cylinder chances are you have at least one bent valve. If even one valve is not sealing properly, it will result in "0" compression for that cylinder. While rebuilding a buddy's 1G a while ago, he had two cracked exhaust valve guides on cylinder 1 which resulted in "0" compression....the valves were not even bent.
     
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  13. 90tsiawdturbo

    90tsiawdturbo Proven Member

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    Ok thanks guys!! Don't know what i'd do without you all!!
     

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