BMW X5 E53 4.4 Crankcase Ventilation Fault and Freezing
Why does the X5 E53 4.4 crankcase ventilation freeze and how do I recognise it?
The crankcase ventilation system freezes or clogs in frost, and oil is forced into the intake manifold and combustion chamber. Symptoms are the engine light, smoking and an oil leak. Freezing is common on the X5, and the cause is often the separator. Also read the fault codes, because the warning light can be caused by something else.
What needs to be replaced in the crankcase ventilation system?
Usually the separator (oil separator), the CCV part and the breather hoses are replaced. The separator is at the back of the engine on the right, and its rubber hose can be brittle. The diaphragm at the end of the intake manifold can also break and let oil into the intake.
How do I keep the crankcase ventilation from freezing in frost?
The breather hoses can be insulated and heated, for example with a heating mat. Covering the openings at the front also helps. Many short trips build up sludge in the hoses, which freezes more easily.