Post by gen1pat on Apr 24, 2013 20:37:25 GMT -6
Many people freak out when their engine smokes. There are 3 types of "smoke", but, only one that is worth worrying about. And that is blue smoke...
Blue smoke, is the result of the engine burning oil. There are two reasons for an engine to burn oil. (1) a valve seal, or both seals, are weak. When they are weak, they allow oil to pass between them and the valve stem, which them enters the combustion chamber. Once in the combustion chamber, the engine will smoke on start up. That start up smoke, is only really prevelant on cold starts (first start of the day or after completely cooling down). The reason for this is because when the engine cools, so do the valve seals, which are made of various types of rubber (depending on MFG). Rubber gets hard and shrinks when cold, and becomes softer and expands when it gets hot. So, when the valve seal(s) are shrunk (cold) oil can get past them and into the combustion chamber, if they are worn enough.
(2)Blue smoke while the engine is continuesly running, is due to worn oil control rings, and the top end needs to be rebuilt. Until the cylinder can be inspected and measured, you do not know if you can get away with a re-hone and only need to install new rings. But, for the price of rings VS the Ebay prices of Wisecos, it doesn't pay to re-use an old/worn piston.
The lesser concerning smokes are black, and white. Black, is the product of excessive fuel being burned in the cumbustion chamber, a condition known as "rich". Reasons for this are; improperly jetted carb, filthy air filter, restricted exhaust, faulty carb parts (worn o-rings/fuel valve/float/etc...), or even a fouled spark plug. While running "rich" won't cause engine damage, it will foul spark plugs and reduce engine performance. If the engine is running "rich" due to a filthy air filter, the air filter itself can cause engine damage; from allowing dirt and debris to enter the engine.
White smoke, generally happens when the engine and/or outside temp is extremely low. Many people confuse this white smoke with blue smoke, and think that the engine is buring oil. White smoke is the outcome of the cold weather/engine. In cold climates/weather the air is not only more dense, but, the fuel has a difficult time atomizing (becoming an EXTREMELY fine mist when mixted with air). This difficult time atomizing results in actual droplets of fuel entering the engine. An engine cannot completely burn these droplets (although the engine generally runs well regardless) and thus they become suspended in the exhaust gasses, forming the dreaded white smoke people freak over. To give an example, ever start up a car on a winter morning? Everyone has, and EVERYONE has seen the white smoke practically billowing out of the tailpipe! That IS the suspended fuel particals. Once the engine reaches operating temperature that white smoke is nearly completely gone. Am I right? Or, am I right? Lol. The opposite is true in hot weather, start up a car on a summer morning, and you never see any white smoke. That is because the outside temp is at a level that the fuel is able to atomize and not become droplets. The engine istelf is also warmer before start up due to the hotter outside temp.
So, if anyone has a concern about "smokes", read this!
Blue smoke, is the result of the engine burning oil. There are two reasons for an engine to burn oil. (1) a valve seal, or both seals, are weak. When they are weak, they allow oil to pass between them and the valve stem, which them enters the combustion chamber. Once in the combustion chamber, the engine will smoke on start up. That start up smoke, is only really prevelant on cold starts (first start of the day or after completely cooling down). The reason for this is because when the engine cools, so do the valve seals, which are made of various types of rubber (depending on MFG). Rubber gets hard and shrinks when cold, and becomes softer and expands when it gets hot. So, when the valve seal(s) are shrunk (cold) oil can get past them and into the combustion chamber, if they are worn enough.
(2)Blue smoke while the engine is continuesly running, is due to worn oil control rings, and the top end needs to be rebuilt. Until the cylinder can be inspected and measured, you do not know if you can get away with a re-hone and only need to install new rings. But, for the price of rings VS the Ebay prices of Wisecos, it doesn't pay to re-use an old/worn piston.
The lesser concerning smokes are black, and white. Black, is the product of excessive fuel being burned in the cumbustion chamber, a condition known as "rich". Reasons for this are; improperly jetted carb, filthy air filter, restricted exhaust, faulty carb parts (worn o-rings/fuel valve/float/etc...), or even a fouled spark plug. While running "rich" won't cause engine damage, it will foul spark plugs and reduce engine performance. If the engine is running "rich" due to a filthy air filter, the air filter itself can cause engine damage; from allowing dirt and debris to enter the engine.
White smoke, generally happens when the engine and/or outside temp is extremely low. Many people confuse this white smoke with blue smoke, and think that the engine is buring oil. White smoke is the outcome of the cold weather/engine. In cold climates/weather the air is not only more dense, but, the fuel has a difficult time atomizing (becoming an EXTREMELY fine mist when mixted with air). This difficult time atomizing results in actual droplets of fuel entering the engine. An engine cannot completely burn these droplets (although the engine generally runs well regardless) and thus they become suspended in the exhaust gasses, forming the dreaded white smoke people freak over. To give an example, ever start up a car on a winter morning? Everyone has, and EVERYONE has seen the white smoke practically billowing out of the tailpipe! That IS the suspended fuel particals. Once the engine reaches operating temperature that white smoke is nearly completely gone. Am I right? Or, am I right? Lol. The opposite is true in hot weather, start up a car on a summer morning, and you never see any white smoke. That is because the outside temp is at a level that the fuel is able to atomize and not become droplets. The engine istelf is also warmer before start up due to the hotter outside temp.
So, if anyone has a concern about "smokes", read this!