Vacuum Pump

A vacuum pump is a necessary part of many of today’s cars, trucks, and SUVs. It is either a mechanical engine-driven pump, or an electrically powered pump. Whichever type of vacuum pump is used, its primary purpose is to generate supplemental vacuum, over and above what the engine can produce on its own.

This vacuum is then used for important functions like assisting you when you apply the brakes, controlling your heating and air conditioning system, and operating emissions controls like your exhaust gas recirculation system. Because of a vacuum pump’s responsibility for braking, it is considered a safety-related component.

While most gasoline engines of the recent past produced sufficient vacuum on their own, modern engines equipped with turbocharging, direct injection, and variable valve timing do not. Diesel engines in general do not produce any vacuum at all, so all diesel vehicles must have a vacuum pump.

Does your car have a vacuum pump?

If your car is powered by a diesel engine, or has a gasoline engine with variable valve timing, direct fuel injection, a turbocharger, or a start-stop system, you probably have a vacuum pump. Hybrid vehicles, battery electric vehicles, and fuel cell vehicles can also have vacuum pumps, usually of the electric type. Otherwise, you can check your owner’s manual, or contact the service department of your brand’s car dealership, to determine whether your car has a vacuum pump.

What are the signs of a bad vacuum pump?

If you're driving a car that has a vacuum pump, there can be several ways for you to tell whether it's bad:

• Braking becomes difficult: A bad vacuum pump can result in less vacuum output, which means less of a power assist when you step on the brakes. You may notice that you must push much harder to stop your vehicle. The brake pedal will feel very hard, without much “give.” Do not delay — call your mechanic and have this fixed before you are unable to stop.

• Your air conditioning, heating or ventilation systems stop working: If you have a bad vacuum pump, you may lose some or all of your climate control system’s functionality. Contact your mechanic and have your car checked out — if it’s summertime or winter, do it right away, so you can continue riding in a comfortable car whose windows you can see out of.

• Oil leaks on the ground underneath your vehicle: Leakage of oil onto the ground can be a common symptom of a bad vacuum pump of the mechanical type. Your mechanical vacuum pump requires oil flow for lubrication and cooling. If you can identify any oil leaks coming from your mechanical vacuum pump, get your car to your mechanic promptly for repairs. And before you start your car, check the oil first, to be sure that there is an adequate supply of it in the engine.

Should you drive your car with a bad vacuum pump?

No, not really. Your vacuum pump is responsible for the proper operation of many of the key systems in your car, most notably the brakes. A bad vacuum pump can also disable your defroster, heating, and air conditioning systems. This makes the vacuum pump a critical component to your car’s safety, so you should have any problems with a bad vacuum pump fixed, without delay.

How do you fix a bad vacuum pump?

Your mechanic will diagnose the problem by determining whether you have a bad vacuum pump, or if there is some other type of issue causing your problem. If you do have a bad vacuum pump, your mechanic can remove the bad one from under the hood, and then replace it with a new one.

If you simply have a worn out or broken drive belt (with a mechanical vacuum pump), or a vacuum hose that needs replacing, or a power supply problem (with an electric vacuum pump), the faulty components can be swapped out for fresh replacement parts. When repairs are complete, the mechanic will test your brakes, as well as your heating and air conditioning system for proper operation.

Can you replace a bad vacuum pump by yourself?

Unless you're experienced in working with vacuum lines and braking systems, this is a job best left to a professional mechanic. A repair related to a key safety system like your brakes is not appropriate for an inexperienced DIYer.