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oil burn at startup

Discussion in 'Mechanic and Repair' started by BRIAN GALLO, May 28, 2003.


    BRIAN GALLO LawnSite Senior Member
    Posts: 282

    I would like to get some more opinions on this phenomenon. Every now and again upon startup my engines will smoke and burn oil. This has happened to all my engines (kaw 14, kohler 14 & 15) at some point. It usually only happens once or twice a season, but still freaks me out when all that smoke comes billowing out for a minute. There seems to be no rhyme or reason to it. Is this caused by a speck of carbon or something getting under a valve seal and allowing a few drops of oil to drain into the cylinder?
  2. atwoodsz

    atwoodsz LawnSite Member
    Posts: 17

    Usually it is from a long run and a fast shut down. Creates a condesation of sorts of oil. Its just the engine clearing its throat. Should generally happen close to a scheduled oil cange or when 1 is past due. As the oil breaks down its easier for it to do this.
  3. Hud

    Hud LawnSite Member
    Posts: 63

    Could be. A lot of my four cycle equipment does the same thing.

    Let's say the oil gets past a valve when the valve is in a certain position when you shut the engine down. Obviously, the valves and piston are not in the same position every time you turn off the engine. But every once in a while, when you shut it down, the valves's in the magic position, and a little oil gets through the guide and/or seal into the cylinder. This would account for it happening every so often. And it only takes a miniscule amount of engine oil to make alot of smoke.

    The valve guides on my 89 HR214 are almost shot. It pours smoke every time I start it when it's cold; after the startup, no smoke. When I shut it down, and let it sit for awhile, oil seeps past the guides so I'll get smoke on the next startup.

    Maybe we could call this the BMW motorcycle syndrome or the Honda Valkyrie/Gold Wing syndrome: Horizontal engine cylinders. Park the bike on its sidestand. Oil in the crankcase is trying to migrate past the valves into the cylinders. Valves occasionally get in the magic position. A little oil migrates into the cylinders. You get the occasional oil smoke on startup.
  4. Robert Doubrava

    Robert Doubrava LawnSite Senior Member
    Posts: 342

    The reason why it smokes at startup is because your valve guides are worn. I have lots of old engines that do the same thing. When you shut them down oil gets in the combustion chamber and when you go to start it again, it smokes due to the oil in the cylinder.

  5. Happens mostly on horazantal engines, for exactly what was posted above "valvle guides and seals".

    Won't get much of that on a vert engine.

    It is comman and nothing to worrie about, your engine settels out and you get a white puff of smoke on start up.

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