Automotive Service Excellence (ASE) A8 Engine PerformanceGeneral Engine DiagnosisMedium
During a routine inspection, a technician notices that the engine's crankcase breather hose is collapsed and severely restricted. How might this condition affect engine operation and oil consumption?
- AIt would result in a lean air-fuel mixture and improved fuel economy.
- BIt would cause increased crankcase pressure, potentially leading to oil leaks and increased oil consumption.
- CIt would lead to excessive engine vacuum and reduced oil consumption.
- DIt would have no significant effect on engine operation or oil consumption.
Show answer & explanationAnswer & explanation
Correct answer: B. It would cause increased crankcase pressure, potentially leading to oil leaks and increased oil consumption.
A collapsed or restricted crankcase breather hose prevents proper ventilation of the crankcase. This leads to increased pressure, which can force oil past seals and gaskets, causing leaks, and can also push oil into the combustion chamber, leading to increased oil consumption.
Why the other options are wrong
- A. While a severe restriction could potentially affect the PCV system's contribution to intake vacuum, its primary impact is on crankcase pressure, not directly causing a lean mixture or improved fuel economy.
- C. A restricted breather hose would cause *increased* crankcase pressure, not excessive engine vacuum, and would likely *increase* oil consumption.
- D. A restricted crankcase breather hose can have significant negative effects, including oil leaks, increased oil consumption, and potential damage to seals.
Crankcase Breather Restriction
A blockage in the crankcase ventilation system that prevents the escape of blow-by gases and pressure.
- Leads to increased crankcase pressure.
- Can cause oil leaks from seals and gaskets.
- May increase oil consumption by forcing oil into the intake or combustion chamber.
- Affects PCV system operation.
Memory trick: Breather Blocked? Pressure's Knocked! Oil's Forced, Seals are Rocked!