Concerned exhaust valve clearance zero

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

  1. ericg

    ericg LawnSite Silver Member
    Messages: 2,792

    Here is a thread from Garage Journal that deals with a B&S engine that had similar issues and valve growth is discussed.
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  2. Tcartwri

    Tcartwri LawnSite Member
    Messages: 30

    Are you running propane specific oil? Propane can produce allot of deposits on the valves and lead to overheated valves if they are held off the seat.
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  3. ed2hess

    ed2hess LawnSite Fanatic
    Messages: 14,588

    ok I will have to get fitting for that size plug. Think I will let unit set until I can run test and use backup.

    now that makes sense.I remember grinding valves on FB460 and then would have to remove the valve and grind the tip to get clearance. Kinda makes me wonder about how running propane affects engine. I thought I was doing a good thing that would increase life.
  4. jkilov

    jkilov LawnSite Bronze Member
    from MS
    Messages: 1,415

    A local guy does LPG conversions and said valve problems are quite common on converted engines.

    Intake valves rely on gasoline for cleaning. When converting to LPG some sort of auxiliary valve lubrication system is added.

    Unlike gasoline, propane burns hotter and slower on richer fuel/air ratios which can cause exhaust valve/seat wear. I believe most OEM propane engines come with hardened valves and seats.

    What Ed2Hess need to do is have his regulator checked. Next take a compression reading and if low a valve job needs to be done.
  5. Tcartwri

    Tcartwri LawnSite Member
    Messages: 30

  6. ed2hess

    ed2hess LawnSite Fanatic
    Messages: 14,588

    Well they don't match......120 and 165. The 120 is on the side where I apparently had valve wear. Sure would like to run until winter before I pull that head. Sure hope the seat is not damaged.
  7. tigerepairdotcom

    tigerepairdotcom LawnSite Senior Member
    Messages: 330

    Not exactly but close!
  8. ed2hess

    ed2hess LawnSite Fanatic
    Messages: 14,588

    Not that it matters but I think it was the exhaust that was tight. Having the valve seats replaced would be costly and new heads probably cost
    An arm and leg. As long as compression holds I am going to run it.
  9. Bashby

    Bashby LawnSite Senior Member
    Messages: 445

    I found some used heads on ebay a while back for my ch25. Might be worthwhile to try to find something cheap to have in inventory. Go ahead and get some head gaskets too... that should guarantee your old one will last forever.
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  10. ed2hess

    ed2hess LawnSite Fanatic
    Messages: 14,588

    Thanks for help.

    Thanks for help....lesson learned on doing aftermarket propane install.

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