On top of all that is already happening inside an engine, there needs to be a constant vacuum source. For naturally aspirated cars, vacuum isn't hard to come by as they produce their own at all times. Turbocharged engines, on the other hand, can use all of the help they can get. The boost pressure a turbocharger produces is the exact opposite of a vacuum, its positive boost pressure. All modern turbocharged engines are equipped with a vacuum pump to combat the positive boost pressure.
What is a vacuum pump?
The vacuum pump is as described; it's a pump that provides a vacuum. In modern European vehicles, you'll find either a mechanical vacuum pump or an electric pump. Each type of pump has its advantages and disadvantages. The pumps are put into vehicles to combat the positive boost pressures put out by turbocharged engines.
Mechanical vacuum pumps, such as those used by BMW on their N20 engine, are driven directly from the engine. In BMW's case, the pump operates off the back of one of the camshafts. These mechanical pumps are lubricated directly by the engine's oil and feature a spinning rotor inside the pump housing to generate its vacuum. So long as the engine runs and the pump is well lubricated, it will continue to provide a vacuum.
The mechanical pumps are quiet and can last a long time, but their placement on the engines can make for a hard time during a replacement. Additionally, a vacuum pump will break the engine's camshaft or timing components if it seizes from a lack of oil. Other oiling issues include worn seals in the pump leading to oil in the vacuum system.
Electric vacuum pumps have quickly become the go-to choice for European manufacturers. These pumps are just as reliable as the mechanical units and have a larger range of benefits over a mechanical pump.
For starters, the pumps use electricity rather than being driven off of the engine. Because the pumps only require electricity, engineers can find the perfect spot in the engine bay to put the pump to move around weight and make the pump more accessible. The pumps can be noisier than their mechanical counterparts, but they are cheaper to replace and won't cause catastrophic engine failure if they break.
What does a vacuum pump do?
The vacuum pump aims to provide a vacuum to several different places in the engine bay. The booster on power brake systems is one of the critical components that require a vacuum. The vacuum pump makes sure that the booster stays under constant vacuum to provide adequate braking force. Emissions solenoids and turbocharger wastegate actuators also require a vacuum to perform as intended. If these parts don't receive a vacuum, they won't function properly and trip a corresponding check engine light.
If you have a modern car, you should ensure that your car's vacuum pump is functioning optimally. As an example, here's how to diagnose and replace the vacuum pump on the popular BMW N20 engine. Depending on the car you own, replacing the vacuum pump isn't a complicated task, and can done at home with basic hand tools.
So there you have it. You'll never wonder why you need a vacuum source again. If you're interested in more Tech Tips for your European vehicle, you can visit blog.fcpeuro.com and subscribe to our YouTube channel.
Owner of a flat-six swapped 1998 Impreza 2.5RS and a 1973 Porsche 914. Horizontally opposed views, only.