14 Questions
What is the purpose of crankcase ventilation systems?
To decrease the chance of sulphuric acid forming in the oil
Why are combustion gases often referred to as 'blow-by'?
Because they escape past the piston rings into the crankcase
What would happen if blow-by gases remained in the crankcase?
Increased chance of oil leaks
How do water vapours enter the crankcase?
As air enters the crankcase
Why is it important to remove combustion gases from the crankcase?
To reduce the chances of forming an emulsion with water and oil
What happens when exhaust gases containing water vapour enter the crankcase?
An emulsion or sludge is formed when mixed with oil
What is a potential consequence of the engine operating at low temperature and load?
Oil foaming
What is the purpose of the crankcase ventilation system?
Remove water and oil vapors from the engine
Why might oil not reach the crankcase ventilation system in a low operating temperature scenario?
Defective thermostatically controlled devices
What can cause increased crankcase pressure and turbocharger seal leakage?
Plugged outlet tube
What problem is associated with venting the crankcase back into the intake post-2007?
Contamination of turbocharger and intercooler
What is a possible consequence of a plugged fresh air inlet vent/filter?
Inoperative ventilation system
How does the crankcase ventilation system contribute to extending the service life of engine oil?
By removing harmful contaminants regularly
What issue is associated with a bent outlet tube in the crankcase ventilation system?
Crankshaft seal leakage
Study Notes
Crankcase Ventilation System
- Removes combustion gases and water vapours from the crankcase.
- Maintained by the Heavy Equipment Technician.
System Function
- Combustion gases escape past piston rings and enter the crankcase during normal engine operation.
- These gases are pressurized, especially in turbo-charged engines.
- Oil leaks can occur if crankcase pressure becomes excessive.
- Removes combustion gases, water vapours, oil vapours, and fuel vapours from the crankcase.
- Prevents formation of sulphuric acid in the oil and oil foaming.
System Operation
- Diesel engine crankcase ventilation system is a modified road draft system.
- Consists of an outlet tube and an inlet filter on the valve cover.
- Creates a low-pressure area at the outlet tube, drawing vapours from the crankcase and dispersing them into the atmosphere.
- Fresh air enters the engine through the filter on the valve cover.
System Service
- Condition and operation of the crankcase ventilation system are crucial.
- Excessive crankcase pressure can cause oil leaks, contamination, and sludge buildup.
- Outlet tube can become plugged with dirt and road debris, or bent during vehicle operation.
- Fresh air inlet vent/filter can become plugged with dirt, oil, or sludge.
Positive Crankcase Ventilation (PCV)
- Venting the crankcase back into the intake allows vapours to be burned in the engine.
- Venting unfiltered into the atmosphere is no longer allowed after 2007.
- Can be vented back into the intake on a turbocharged engine, but with contamination issues.
- Solutions include using a pleated depth type filter or a centrifugal action system to separate oil from vapours.
Learn about the purpose of crankcase ventilation systems and the importance of maintaining them in heavy equipment. Explore the removal process of combustion gases and water vapors from the crankcase.
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