pressure gauges under the hood of a car

Vacuum pressure plays a critical role in keeping your engine running smooth, and performing it’s best. From Dennis Road Automotive in Dallas, TX, here’s some info on vacuum pressure, why you need it, and how to tell if you’ve got a vacuum leak.

What is vacuum pressure? You probably already understand the concept of vacuum - it’s a negative pressure difference relative to the atmosphere. But what place does vacuum have in the way a vehicle’s engine operates? Vacuum is created while the engine is running. As the engine draws air into the cylinders and burns it off, it creates a negative pressure difference in the intake manifold. At some point, somebody figured out that vacuum was useful for other things, and now multiple systems and the running condition of the engine rely on vacuum.

Why do you need it? Vacuum pressure is important for a variety of reasons. First and foremost, Your engine is tuned to the amount of vacuum it’s supposed to have, and it allows for an even draw of air into the engine. Depending on the model vehicle you drive, vacuum also regulates transmission shift points, the climate control system, emissions components, braking, and sometimes even parts like door locking mechanisms. On diesel engines, it’s particularly important; many diesel engines even rely on vacuum to shut the engine off.

What happens when there’s a leak? Some vehicles seemingly have miles of vacuum lines that run throughout the engine bay and the inside of the car. All these lines are attached to modules and diaphragms, any of which can fail and develop a leak. The gaskets that seal your intake manifold to the engine can also develop a leak. Whenever there’s a vacuum leak somewhere in the system, a variety of symptoms may arise; it depends on where and how severe the leak is. At its most benign, a vacuum leak will cause the engine light to illuminate, or the vent controls in your dash to operate erratically. At its most severe, it can affect transmission shifting to the point of damage, or the vehicle may fail to start at all. Typically, a vacuum leak will cause situations like hard starting, rough idle, excessive fuel consumption, and engine codes. You might even be able to hear a leak - sometimes a whooshing or whistling sound can be heard with the engine running.

What do you do about it? If you have a vacuum leak, no matter the size, your car isn’t operating optimally. Getting a vacuum leak fixed can range from removing the entire intake manifold to replace the gaskets, to tracking down a hose that’s come unplugged. They are notoriously hard to track down sometimes; but with the right diagnostic equipment and knowledge, professional technicians can have a vacuum leak found and fixed in no time.

If you think you may have a vacuum pressure problem, let us take a look. It’s typically a simple fix that’ll leave you glad you stopped by. For the best fleet and diesel service shop in Dallas, TX, call or stop by Dennis Road Automotive today.


Thank you for visiting Dennis Road Automotive in Dallas, TX. Count on our automotive repair technicians to keep your car, truck, suv, or van on the roads longer and safer.

Schedule your appointment today (972) 241-1901 or REQUEST APPOINTMENT HERE.

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11155 Dennis Rd | Dallas, TX
(972) 241-1901
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