Monday, 18 March 2013

Crankcase Ventilation Valve (CCV) + DIY Replacement

The CCV takes oily crankcase gases (found in all internal combustion engines), separates the oil, returns the oil down the dipstick tube to the sump, and recycles the gases into the intake to be combusted.

If your daily commute is relatively short, and the engine rarely gets up to full operating temp, you need to worry. Solution: take it for a hot highway drive for about 30 minutes every week or two.

If your daily commute is not short, and the engine gets up to full temp every time you drive, you have no need to worry... for now.


1. Pressure Regulating Valve
2. Vent Pipe
3. Connecting Line
4. Vent Hose
5. Bolt
6. Vacuum Hose
7. Return Pipe
8. Dipstick O-ring 

Determining If Needing Replacement 

1) Cracks in the air hoses leading to and from the CCV.
Symptoms: lean condition, P0171 and P0174.
Diagnosis: Remove oil filler cap while at idle. Leaking CCV system will cause stumbling and a very strong suction on the oil filler cap.

2) Failure to separate oil from vapour
Symptoms: More-than-expected oil consumption - oily crankcase gases are being returned to the intake instead of separated properly.
Diagnosis: Check plugs and DISA for oil contamination.

3) Clogged with oil-ice or sludge
Symptoms: 'splosions in the engine bay
Cause: Short trips in cold weather, allowing moisture (inherent to gasoline combustion) to get in the oil and never burn off. Moisture mixes with oil and makes yellow snot. Yellow snot sticks in CCV, car is left outside in freezing temperature, snot turns to ice-snot, then the crankcase vapours that the CCV is supposed to separate instead just build pressure inside the crankcase... until POW!
Early Diagnosis: yellow goo or black sludge under the valve cover or on the underside of the filler cap
Late diagnosis: oil all over the place, terrible lean conditions, maybe oil fills the cylinders, wallet vanishes.

DIY Replacement