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How to Deal with a Vacuum Hose Leak in a BMW

by Dutch Silverstein November 4, 2021

Being held to a higher standard than most, BMWs are sent through rigorous testing throughout the manufacturing process. While each part is thoroughly inspected, BMWs can experience problems with the vacuum hose resulting in a vacuum hose leak.

BMWs are manufactured with a vacuum hose which is a flexible rubber connection that holds a manifold vacuum to various other parts that require vacuum power. The amount of vacuum hoses on your vehicle depends on the vehicle’s age, make, and model. You may have one or more hoses on your BMW.

Vacuum hoses are used to power the PCV valve, HVAC controls, brake booster, and the heater control valve. The intake manifold is one of the main sources of power to other components that require vacuum power to function. It is responsible for distributing the combusted fuel and air mixture that is required for the full, proper function.

Warning Signs of a Vacuum Hose Leak

There are several warning signs associated with a vacuum hose leak. The first and most common sign is an illuminated check-engine light. There are many sensors surrounding the vacuum hose, and any type of leak from the hose would easily be detected through the vehicle’s onboard system. It will alert you through the signals on your dashboard, so you can bring your BMW in right away for service.

Secondly, drivers may notice improper engine function. When parts that are connected to the vacuum hose are not getting enough power from the intake manifold, the engine is unable to run as smoothly as expected. Drivers report their BMW exhibits a rough engine idle as a result of a vacuum hose leak. This will be easy for you to detect, since you’re used to how your BMW feels in idle.

Last, as a result of a large vacuum leak or a leak that has occurred for an extended period of time without being fixed, the engine may not function at all. A vacuum hose leak leads to high amounts of pressure within the hose. In turn, this pushes out the head gasket leading to a broken cylinder head. With the broken cylinder head, combustion occurs within the engine instead of the combustion chamber, which is extremely dangerous. This can result in a dangerous accident, so please bring your car in for a diagnostic check if you suspect an engine problem.

BMW drivers that have experienced a vacuum hose leak often report their vehicle producing strange noises such as hissing or sucking noises. In addition, drivers have reported engine stalling as a result, so beware of the symptoms and seek help if needed.

What causes a vacuum hose leak?

There are a number of reasons for BMWs to experience a vacuum hose leak including the below:

  • A damaged hose: The hoses are made of pretty durable plastic. However, with exposure to extreme heat, the hose experiences general wear and begins to break or crack resulting in a leak.
  • A disconnected hose: Over time, fittings around the hose break due to normal wear or cracking from the heat. As a result, the vacuum hose becomes disconnected.
  • Worn seals and gaskets: The seals and gaskets attached to vacuum hoses are often made of a rubber material. The heat that is radiated from the engine compartment dries out the rubber leaving them damaged and cracked. This is hard to detect.
  • Broken or damaged parts: A vacuum hose is connected to several other parts. When the connection fails due to damage to other parts, the hose is no longer able to hold a proper connection to the part itself resulting in a leak.

BMW Vacuum Hose Leak Repair

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A&M Auto Service has been helping drivers of Pineville and the surrounding areas including Charlotte and Greensboro, NC for more than 23 years. Rob “Dutch” Silverstein opened a shop that quickly became Charlotte’s #1 European, Important, and Domestic automotive repair shop.

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