Small Engines that are Smoking

Posted: July 29th, 2011 | Author: | Filed under: Uncategorized | No Comments »


Many small engines are in good repair, but they start smoking when you start them up. In many cases, you may be able to fix this on your own. Here are some quick tips on what to look for to try to solve your smoking small engine.

  1. You may have a dirty or plugged air filter. Replace or clean it.
  2. Worn Damaged Rings. Rings and cylinder may be worn past their tolerances due to age and lack of maintenance. In this case it, bring the engine in to be evaluated for repair options.
  3. Loss of crankcase vacuum. Make sure the dipstick or fill plug is secured tightly. You may also have bad O-rings, gaskets and washers. 
  4. Scored cylinder. This is caused by ingesting dirt. Either a very dirty air filter or a missing air filter will cause this.
  5. You may be using the wrong grade/viscosity of oil. It is very important to use the proper viscosity recommended by the manufacture. It is also important to use oil designed for Air-Cooled Engines, most oils in stores are designed for automobiles with water cooled engines.
  6. Some engine failures are due to Gasoline. Either  gas sitting stagnant and clogging the carburetor, or the Ethanol in the gasoline has caused some kind of failure to the components.  The float no longer shuts off the gas and causes it to leak into the oil. This will also cause the engine to smoke and will required repair. 
  7. Leaking head gaskets. A head gasket typically leaks due to the engine overheating . Nesting or grass build up in your engines cooling fins prevent the proper amount of air circulation to cool itself and the engine overheats, warping the cylinder head causing the gasket to no longer seal properly. Low oil, Running the engine for a long period of time with low oil will also cause the engine to overheat, when the oil is then filled to the proper level it leaks by the head gasket. This situation would have to be diagnosed and repaired.
  8. The choke is still on. Open the choke as soon as the engine fires and continues to run without stoppping.
  9. There may be too much oil in the engine. Correct the amount of oil in the crankcase. Fill it only to the "Full" mark.



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