Concerned exhaust valve clearance zero

Discussion in 'Mechanic and Repair' started by ed2hess, Aug 29, 2014.

  1. ed2hess

    ed2hess LawnSite Fanatic
    Posts: 13,139

    Engine BS Vanguard 613177 type 0114-e1 code 5122612. This unit has about 1000hours, first time to check valve clearance. How can the clearance be zero or less on the exhaust on one side? I checked and double checked to be sure the valve stem was in the saddle on both ends.

    The other 3 clearances ran .006 - .011. I readjust all to .006" and the
    Unit started and ran but I shut it down thinking I may missed something.
     
  2. Tcartwri

    Tcartwri LawnSite Member
    Posts: 30

    It was likely set that way from day one.
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  3. tigerepairdotcom

    tigerepairdotcom LawnSite Senior Member
    Posts: 324

    Umm.. Did you check the valves while the engine was still hot?

    I know it is a silly question but the engine must be 100% cool.

    the reason there is valve lash to begin with is thermal expansion. If the engine is hot the metal in the valves be expanded and you will not be able to accurately read the clearance.

    Metal expands when it is heated as the particles move further apart.
     
  4. tigerepairdotcom

    tigerepairdotcom LawnSite Senior Member
    Posts: 324


    If it was set that was from day 1 the valve would have likely burned in many fewer than 1000 hours. Also if you set the valve lash to zero on a cold engine it is not likely to run once ti warms up.

    So if you set the lash while the engine was hot. Re set with the lash with engine cold.
     
    Last edited: Aug 29, 2014
  5. ed2hess

    ed2hess LawnSite Fanatic
    Posts: 13,139

    It wasn't hot I pulled it in shop and took awhile to get plugs out and covers off. If it was hot it should have clearance right? The unit got to the point that it would only start cold. It is propane. When really hot I could hear a pop which was probably ignition with the exhaust open a little. It bothers me that it would wear in and get tighter? The adjusting nut was tight.
     
  6. Tcartwri

    Tcartwri LawnSite Member
    Posts: 30


    Not really. Valve would have run a little hot, yes.
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  7. tigerepairdotcom

    tigerepairdotcom LawnSite Senior Member
    Posts: 324

    Ed2hess here is my suggestion. Adjust valves cold and then run a compression test just to make sure they match. And let us know what you find
     
  8. tigerepairdotcom

    tigerepairdotcom LawnSite Senior Member
    Posts: 324

    An exhaust valve can burn if the valve clearance closes up for some reason (improper adjustment, cam or lifter wear, a bent push rod, worn rocker arm or cam follower, etc.). The lack of clearance in the valvetrain prevents the valve from closing fully, which causes it to leak compression and overheat.

    I pool my knowledge from over 5000 hours of cylinder rebuild work over 4 years of being a mechanic in the USMC and having a mechanical engineer as a father... What basis of knowledge do you pool from stating that a valve will not burn if the clearance is set to 0 at cold?
     
  9. Tcartwri

    Tcartwri LawnSite Member
    Posts: 30

    I guess you missed the part where he measured it shortly after running it.
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  10. Bashby

    Bashby LawnSite Senior Member
    Posts: 446

    So your question is about how valvetrain wear can make clearance tighten asopposed to loosen?
    Valve seats can wear causing the valve to recess in the head andthe valve itself can deform. Id adjust it to spec and run it. Maybe check it again in a couple hundred hours to see if ittightens up again.
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