How to Adjust the Vacuum Booster?
4 Answers
Cars' vacuum boosters need adjustment. You can connect the vacuum tube on the vacuum booster, start the engine, and let it run at idle speed. Wait for the vacuum booster to enter normal working conditions, then measure its values. More details are as follows: 1. The vacuum booster uses vacuum to increase the force the driver applies to the pedal. It is generally located between the car's brake pedal and the master cylinder. 2. For ease of installation, it is usually integrated with the car's master cylinder as a single unit, with part of it extending into the vacuum booster's housing. The car's vacuum booster mainly consists of a vacuum servo chamber and a control valve. 3. When the driver presses the brake pedal, the control force from the pedal mechanism pushes the control valve push rod 12 and the control valve plunger 18 to move forward.
I recently checked the vacuum booster in my car myself, mainly because when it fails, the brake pedal becomes very hard, making driving quite strenuous. First, I opened the engine hood and located the vacuum hose connected to the brake master cylinder, feeling for any air leaks by hand; if there's a hissing sound or the hose is aged, it needs to be replaced. Then, I checked whether the engine's vacuum supply was stable, which can be measured with a vacuum gauge—normal readings should be between 20-30 inches of mercury. If all these are normal but the booster still doesn't work, it's likely that the booster itself is faulty and needs to be replaced entirely. Not all cars allow direct adjustment of this component, as most are designed to be fixed. Tampering without proper knowledge could affect the braking system, so it's best to refer to the vehicle's manual or look up information online to ensure safety first. Regular maintenance, such as cleaning the hoses, can extend the booster's lifespan.
Over the years working in the auto repair shop, my common approach to vacuum booster issues starts with diagnosing symptoms: if the owner reports sudden brake pedal stiffness, we first use a vacuum tester to check engine vacuum levels. If the vacuum is low, we inspect rubber hoses and connections one by one for cracks or looseness; any found leaks prompt direct part replacement. For a severely internally leaking booster itself, replacement is the only option as there's no equipment on the market to adjust it. Simultaneously, we check if the brake pedal's free travel is normal, as this relates to the booster. The entire process is straightforward, but don't attempt DIY—beginners often overlook details, and incorrect installation could lead to brake failure. We recommend having a professional technician inspect it every 2 years to prevent minor issues from turning into major repairs.
Last week, my car had an issue with a heavy brake pedal. After searching online, I found it might be a vacuum booster failure. I couldn't adjust it myself because it's a sealed component designed to be non-serviceable. I consulted an experienced mechanic I know, who tested the vacuum system for me. It turned out to be an aging, leaking hose, which was fixed by replacing it for just a few dozen yuan. If the booster makes abnormal noises or has a vacuum leak, it generally needs to be replaced entirely. Driving with faulty brakes is really scary, so it's best to get it checked at a professional shop early. Never skimp on this expense—safety is more important than anything.
