What are the Causes Behind Air/Oil Separator Failure in Porsches?

Porsche Air Oil Separator Failure Fix

Porsche: the name comes imbued with characteristic German capability, speed, engineering, and looks. Flashy, sophisticated, fast, stylish, luxurious—Porsche can (and does) do it all. The car preferred by sporty celebrities and wealthy parents alike, there is no doubt that Porsche cars are a great purchase. Despite their glitz and glamour, however, Porsches can face the same sorts of maintenance and technical failures as a run of the mill family car. One example is the air/oil separator—with turbo-charged engines and other add-ons, Porsches face problems just like anything else.

What is the air/oil separator in a Porsche?

The air-oil separator is found in all Porsches, and is not unique to a specific style. It’s an emissions device placed in the back corner of the engine, generally on the top right-hand side. Its primary function is to collect lingering gas and vapor remaining in the crankcase, and funnel those gases back into the intake manifold. There, they are burned in the regular combustion chamber. The main job of the air-oil separator is to reduce emissions for the car overall.

What happens when it fails?

When the air-oil separator fails, the results are not catastrophic, but if left untreated for a while, it can result in damage to the engine. If the air-oil separator is not working properly, it cannot separate the oil from the “air” that it is sucking back to be combusted, and oil is pulled into the intake manifold. This is not good for the engine, and can interfere with spark plugs and catalytic converters.

What are the warning signs?

One of the most common—and telling—indicators that the air/oil separator is not functioning correctly is a large quantity of white smoke pouring out of the engine area. While this doesn’t happen every time, it is common enough to indicate air/oil separator failure across the board. Generally, the smoke will be accompanied by check engine light (the oil being drawn into the engine reduces the normal levels), and the oil cap can become very difficult to remove. This is due to the high vacuum levels of the engine.

The engine may also make a high-pitched squealing sound as air is being drawn through the crankcase seal—again, due to the high vacuum on the inside. Other indicating possibilities include oil leaks and dark smoke coming from the exhaust pipe.

If any of these signs occur, it’s absolutely crucial to take your Porsche to a specialized mechanic right away to avoid any long-term or reoccurring damage.

How can you fix or avoid it?

The best way to avoid any sort of problems, especially in a high-end Porsche, is to consistently and regularly follow the maintenance schedule proposed by the manufacturer. This information should be readily available in the owner’s manual that comes with the car, and further (or follow-up) questions can always be directed to a Porsche dealer or your mechanic.

However, it’s possible to do a little diagnosis yourself: measure the engine crankcase vacuum with a slack tube manometer by making a hole in the top of an old filler cap and adhering the gauge. The normal pressure ranges between four to seven inches of water—if the air/oil separator has failed, it will be between nine to twelves inches. If a manometer is not available, a regular vacuum gauge should work fine. If you are not sure—or don’t like to fiddle around under the hood—a mechanic should be able to diagnose the problem easily.

Causes Behind Porsche Air Oil Separator Failure


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* Porsche 911 image credit goes to: Vladimir Mladenovic.

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