What Blowby is acceptable?
The leakage of any combustion gases, air, or pressure into the engine’s crankcase is considered blowby. When measured in cubic feet per minute (cfm), a 12-liter engine in good mechanical condition can experience at idle 1.5 cfm of blowby at normal operating temperature but 3.5 cfm when cold.
What to do if your diesel engine is blowing oil?
Disable the engine from starting (fuel shut-off valve if diesel or coil wire if gas) but still be able to crank the starter. Open the output air service valve and crank the engine over. If air is coming out the air valve while the engine is just cranking then the valve is suspect.
What should I do if my engine oil keeps blowing into the air filter?
Purchase an engine flush formula from your local parts store and follow the directions. In general you will pour the formula into the oil and run the engine for a period of time. Once the engine has been flushed drain the oil and fill it with fresh engine oil. Replace the filter and see if the problem persists.
Why does my Sullair blow oil after getting hot?
If it starts after getting hot it usually is the oil. Many revert to ATF when in doubt. If the air coming out of the service valve is hot it may well be as Moonlite pointed out, the pick-up tube from the receiver to the cooler may be restricted and not permitting proper lubrication to the rotary screws.
Why is the oil blowing out of the rotary screw?
If air is blowing out of the air intake then the issue is more than likely in the check valve at the discharge end of the rotary screw. The check valve is used just for that purpose. They get hot as hell when the oil gets low and have been know to melt, stick in an open position or even catch on fire.
Disable the engine from starting (fuel shut-off valve if diesel or coil wire if gas) but still be able to crank the starter. Open the output air service valve and crank the engine over. If air is coming out the air valve while the engine is just cranking then the valve is suspect.
How to avoid common causes of blow by and oil consumption?
Here are some common causes of blow-by and excessive oil consumption and how you can avoid them on your next engine build. The combustion process is never perfect. Even the best street engine never seals all that combustion pressure. A certain amount of cylinder pressure will always find its way into the oil pan.
Purchase an engine flush formula from your local parts store and follow the directions. In general you will pour the formula into the oil and run the engine for a period of time. Once the engine has been flushed drain the oil and fill it with fresh engine oil. Replace the filter and see if the problem persists.
If air is blowing out of the air intake then the issue is more than likely in the check valve at the discharge end of the rotary screw. The check valve is used just for that purpose. They get hot as hell when the oil gets low and have been know to melt, stick in an open position or even catch on fire.