Renault Megane II crankcase ventilation system maintenance

General structure of the crankcase ventilation system

The location of the elements of the crankcase ventilation system (K4J engine) is shown in Fig. 1.

Operating principle:

At low loads, oil vapours are drawn in in small quantities through a calibrated orifice.
At medium and high loads, oil vapours are drawn in in large quantities through the throttle body.

Diagram of the location of the elements of the crankcase ventilation system of the K4J engine — **Fig. 1. Location of the elements of the crankcase ventilation system of the K4J engine:**
1 — inlet opening of the crankcase ventilation system;
2 — oil deflector of the ventilation system on the cylinder head cover;
3 — calibrated orifice

Diagram of the location of the elements of the crankcase ventilation system of the K4M engine — **Fig. 2. Location of the elements of the crankcase ventilation system (K4M engine):**
1 — crankcase ventilation pipeline;
2 — calibrated orifice;
3 — oil separator of the crankcase ventilation system on the cylinder head cover;
4 — inlet opening of the crankcase ventilation system

Important! To ensure the normal operation of the exhaust gas emission reduction system, the crankcase ventilation system must be kept clean and in good condition.

Cleaning the ventilation system

Preparation for removing the receiver — We remove the receiver to gain access to the crankcase ventilation system

Unscrewing the oil separator securing bolts — We unscrew nine bolts securing the oil separator to the cylinder head cover

Removing the oil separator — We remove the oil separator

Cleaning the oil separator — We clean the oil separator of deposits from the crankcase gases

Removing the old sealant from the oil separator — We remove the remnants of the old sealant from the mating surface of the oil separator

Cleaning the cylinder head cover — We clean the remnants of the old sealant from the cylinder head cover

Refitting: we apply a special sealant to the mating surfaces of the cylinder head cover and the oil separator.

Applying the sealant — We apply the sealant to the mating surfaces

We refit all parts in the reverse order.

Tightening sequence of the oil separator bolts — **Fig. 10. Tightening sequence of the oil separator securing bolts**

Tightening torque: we tighten the oil separator securing bolts to a torque of 13 N·m in the sequence shown in Fig. 10.

Recommendation: after cleaning the crankcase ventilation system, it is recommended to check the engine operation at idling and under various loads to make sure there is no air leak and that the ventilation is normal.