How to Deal With PCV Valve Failure in Your BMW

The PCV valve is an innovation which has been around for decades, and all modern vehicles have one. However, many drivers know little about this essential part and much less about how to tell if it is failing or how to deal with failure when it occurs. In this article, we’re going to get you clued up on the PCV valve, learn what it is, what it does, why it fails, and what you should do about it.

The PCV Valve

The Positive Crankcase Ventilation Valve or PCV valve was created in the 1960’s. It is a valve that was created as a solution to a problem which had plagued motor cars since their creation: blow-by gases. Blow-by gases are released by the engine and are comprised of the vapors of unburnt fuel. These vapours are heavily toxic, and if left to swirl inside your engine, they will literally eat away at components inside your vehicle. The PCV valve was created as a way to ventilate these vapors.

Found under the hood of your BMW, the PCV valve is black and has a red handle. It sucks the blow-by gases away from the crankcase via the intake manifold. It then returns them to the engine where they can be properly burned. On a basic level, the PCV valve is a fuel recycler.

When the PCV valve fails, it allows the highly-toxic blow-by gases to remain in the crankcase, where it can systematically eat away at your BMW’s essential components.

When to Replace the PCV Valve

Of course, now that you know what can happen when the PCV valve fails, you’ll want to know how to tell when failure has occurred or is about to occur. The valve itself rarely fails. Instead, it is the PCV valve’s filter that tends to impede the function of the valve. The filter is an essential part of the PCV valve, as it catches the majority of the toxins in the blow-by gases. Over time, however, the filter can become clogged.

The PCV valve filter should be replaced after every 60,000 miles or as needed. It should also be regularly serviced. The PCV valve does not have a specific time span for replacement and will only need to be switched out if it develops a fault.

Filter Failure Symptoms

If your PCV valve filter is reaching the end of its lifespan, then you should be on the lookout for the following symptoms and warning signs:

• An increase in internal engine pressure
• Seal/gasket failure
• Leaking engine oil
• Black smoke emissions
• Buildup of sludge under the hood
• Wetness under the hood
• Engine surges
• Frequent lean misfire
• Oil found in the MAF sensor
• Increased rate of oil consumption

How to Tell if the Valve is Stuck

If you suspect your PCV valve may be stuck open or closed, you should first rule out MAF sensor failure. This is because MAF sensor failure has very similar symptoms to PCV valve problems and is a far more common and simple fix. You should investigate the likelihood of either issue if you notice:

• When idling, your engine misfires
• Running lean or rich
• Increased rate of oil consumption
• Ignition problems
• General rough idling

Seeking Replacement

You should never try to replace or repair the PCV valve at home. It is a vital part of your BMW that safeguards the rest of its parts from expensive damage. Put simply, it just isn’t worth the risk. PCV repair and replacement also may require the purchase or rental of specialist tools alongside the replacement part, meaning that it will likely end up more expensive than letting a professional switch it out for you. You also won’t get the peace of mind or the longevity that comes with professional repairs.

The Staff at Bavarian Motor Repairs Are Here for You

BMW owners in the Washington D.C., Largo, North East, Upper Marlboro, College Park, and Capitol Heights, MD areas don’t need to worry about where to go for PCV valve failure. With our specialists caring for your car, you’ll never have to deal with a severe vehicle problem again. We are experts in the repair and maintenance of BMW, MINI, and Rolls Royce models. So if you’re the proud owner of any one of these vehicles, we’ll be happy to help get you back on the road quickly and safely.

* BMW X1 image credit goes to: Ingus Kruklitis.