Automotive Troubleshooting Oil Loss Via the Piston Ring/the Valve Guides Inspection
Purpose of inspection
When burning oil causes white smoke to be seen in the exhaust gas, changing the engine rpm to change the volume of white smoke allows you to judge whether oil loss via the piston rings or oil loss via the valve guides exists. As well, disassemble the engine and judge the condition of the accumulated carbon.
Exhaust gas inspection
• Judge if there is oil loss via the piston rings
After warming up the engine, race it at approximately 2000 to 3000 rpm to check the state of the exhaust gas
• White smoke increases when the engine is raced
• White smoke increases when rpm rises
• Judge if there is oil loss via the valve guides
After warming up the engine, let it idle for approximately 5 minutes then race it to check the state of the exhaust gas.
White smoke will discharge for approximately 30 to 60 seconds at the start of
racing, but the amount will gradually reduce.
Why the cause of white smoke can be determined by oil loss via the piston rings
(1) The temperature in the combustion chamber is low when the engine is idle, therefore even if oil loss from the piston rings occurs, the oil does not burn. Therefore, the volume of white smoke is small.
(2) When engine speed increases, the temperature in the combustion chamber rises as does the amount of oil supplied to the cylinders. As a result, the amount of white smoke discharged increases.