Crankcase ventilation (CCV) valve on the M52TU / M54

Engine / equipment

M52TU and M54 six-cylinder petrol (320i–330i E46, 520i–530i E39, 520i–530i E60 up to 2005, X3 2.5i/3.0i, X5 3.0i, six-cylinder Z3 and Z4)

Period mentioned

1998–2006

Symptoms

High oil consumption, bluish smoke, rough idle, whistling from a vacuum leak, engine light with lean-mixture codes and very strong suction when trying to remove the oil filler cap at idle.

Possible cause described

The system has a regulating valve and four plastic and rubber hoses under the intake manifold. The valve membrane tears and the hoses crack; on short trips in cold weather, condensation mixes with the oil, blocks the return through the dipstick tube and can freeze. Several forum owners cut oil consumption sharply by renewing the system, though others also blame piston ring wear.

Check for the garage

At a garage: smoke-test the intake to find leaks (CCV hoses, intake boots, DISA valve seal, valve cover gasket) and check whether the dipstick tube return is blocked. A cold-climate version of the system exists for cold regions.

Cost cited in the source

No verifiable estimate in the sources; ask for a quote. It is labour-intensive because the intake has to be removed.A rough figure from the original database, not an up-to-date quote.

Sources from the original database