BMW E39 M52 oil separator and oil in the intake manifold
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E39 M52: oil in the intake manifold, does the separator need replacing?
The separator diaphragm or the hose leading to the dipstick tube can crack and let oil into the intake manifold. This increases oil consumption and causes an intake leak. Replacing the separator and hoses usually fixes the fault.
Does the intake manifold have to be removed to replace the separator?
No. The separator comes out through the oil filter housing cover or over the alternator. First remove the air filter housing and a few screws. The old separator may not fit out until the power steering reservoir is removed.
The car jerks and has no low-end torque even though the separator has been replaced?
Check for other intake leaks. The rubber plug of the intake manifold can be cracked, and replacing it fixed the low-end torque and idle. Also check the thin hose of the fuel vacuum regulator. Replace the broken parts and reset the engine adaptations.
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