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The brake booster multiplies the force of your foot so a normal push can stop a heavy car. Route 66 Auto Repair in Upland tests boosters when the pedal turns hard, the engine idles oddly when you brake, or you hear a hiss under the dash. We check the booster, its vacuum or hydraulic supply, and the reserve that should carry you through a stall. Then we explain the fix and put it on a written estimate.
What kind of brake booster does your vehicle have?
Most gas cars use a vacuum booster: a round canister between the pedal and the master cylinder that uses engine vacuum to push for you. Many diesels and some gas engines make too little vacuum, so they add a separate vacuum pump.
Some trucks, vans and diesels use a hydraulic booster that borrows pressure from the power steering pump. Newer vehicles, including many hybrids, may use an electric brake booster. Tell us it's a hybrid at intake and we'll explain what we can take on.
Is there a quick booster test you can try?
Yes, with the car parked. With the engine off, press the brake pedal firmly five or six times until it feels hard. Hold steady pressure and start the engine. With a working vacuum booster, the pedal should sink a little as assist arrives. If nothing changes, the booster or its supply is suspect.
This test only tells you to book a proper check. Do not drive a car with a very hard pedal.
Our brake booster service process
Step 1: Confirm the complaint
We feel the pedal, perform the assist test and listen for hissing inside the cabin.
Step 2: Test the supply
Engine vacuum or pump output is measured, and hoses and the check valve are inspected.
Step 3: Test the booster
We check whether the booster holds vacuum and whether it leaks when the pedal is applied.
Step 4: Check related parts
Master cylinder, pedal pushrod and, on hydraulic units, power steering fluid and hoses are checked.
Step 5: Repair and verify
The failed part is replaced after your approval, then we road-test assist and reserve.
What's included in brake booster service
Included on the work order
- 01Pedal assist and reserve test
- 02Vacuum or hydraulic supply measurement
- 03Vacuum hose and check valve inspection
- 04Booster leak test at rest and applied
- 05Pushrod and master cylinder check
- 06Road test
Need-now or need-later?
Need now: call
- A pedal that takes both feet to stop the car
- A hiss under the dash every time you brake
- Loss of assist on a hydraulic booster with a power steering leak
Need later: book
- A slightly firm first stop after the car sits overnight
- A cracked but still sealing vacuum hose
How pricing and timing work
The diagnostic fee is stated at the counter before testing and applies to approved related repair. Sometimes the fix is a hose or a booster check valve. Sometimes the booster itself has failed, which is a larger job because it mounts to the firewall. We explain the difference before any work. AAA members save 10% on parts and labor, up to $75.
Aftercare
A new or repaired booster should give the same light, steady pedal from the first stop of the day. For internal leaks, see our brake booster diaphragm repair page, or call (909) 608-7699.
Frequently asked questions
Can you drive with a bad brake booster?
The brakes still work, but you need far more leg force. In an emergency stop that can be the difference. We recommend not driving until it is checked.
Why is my brake pedal hard only when the engine is off?
That is normal once the vacuum reserve is used up. The booster only helps while the engine makes vacuum or a pump runs. A healthy booster should give you a couple of assisted presses after shutdown.
Do diesels have brake boosters?
Yes. Many use a vacuum booster fed by a separate pump, and others use a hydraulic booster run by the power steering system. We test whichever your diesel uses.