Case Studies

BMW Service Engine Clogged Breather System – Oil Consumption Use

BMW Service Valve Cover
BMW Service Valve Cover –
Note sludge or clogging in ventilation port

BMW Service with N52 Engine – This vehicle came from another shop with an uncorrected engine oil leak and high oil use. Consumption was on the order of 1 quart per 100 miles, yes, you read that right.

We started by finding the incorrect engine oil fill cap had been installed by the previous facility, causing an oil leak on the top of the engine, but that was only one problem. The real culprit was a problem with the crankcase ventilation system. Using our special BMW service diagnostic tool, we confirmed a severely clogged engine breather box, on this engine located in the camshaft cover. Not an easy job as this engine has “Valvetronic”, but one that needed to be handled. In the past, we’ve found these breather failures are much more common in colder weather.

On the earlier BMW service, the ventilation or breather system, sometimes called the oil trap, was replaceable. On the later cars it is now part of the camshaft cover, sometimes called the valve cover, and cleaning a clogged breather is next to impossible, replacement usually being the only proper correction.

In the photos below, you’ll note the large camshaft cover assembly that must be replaced for clogging. Such clogging has become an issue with the later breather systems. The build up of this material prevents the crankcase ventilation system from functioning correctly, and will lead to an increase in crankcase pressure, external oil leakage. In severe cases it can build up enough pressure to damage engine seals, including the rear main seal. Any problem with multiple engine oil leaks must first be dealt with by inspecting and servicing the crankcase ventilation system.

If you car has the symptoms noted above, you might want to give us a call, BEFORE the failure occurs. The update cost is minimal compared to the damage which can result. Our goal at Atlantic Motorcar’s BMW service, to provide the lowest possible cost by preventing problems first, rather than just repairing them.

Here is how you can take some simple precautionary steps:

  1. If you have no choice but to make short trips, try and take your vehicle on the freeway at least once per week, as this will help burn off condensation.
  2. Avoid excessive idling or allowing the car to warm up.
  3. Keep Your vehicle garaged at night, if possible, when the temps are very low.
  4. Change your engine oil every 5,000-7,000 miles, always using full synthetic.
    We strongly advise not to follow BMW’s 12,000-15,000 mile oil change intervals, we have an expression here, “Oil is cheaper than metal”, keep your engine oil clean, and change on a frequent basis and your BMW will serve you well.

    Feel free to call or stop by find out more on how we can help you get your car back to the condition you both deserve! Earning your trust, every time you turn the car…that’s what we do…every day…for the last 30 years.

    Click here see what our happy customers have to say about us and our service at AMC Customer Reviews.
    If you have questions, or if we can be of further assistance, just call us at (207) 882-969, we’d love to meet you, and your car!

    Bruce and the AMC Service Team

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