How to check if the brake booster is airtight on BMW 325i?

Check the brake pedal reserve distance with the engine off. Start the engine with the pedal depressed; if it lowers slightly, it's normal. allow the engine to warm up and then turn the key to "OFF". Gently press the brake and if the pedal lowers initially but rises after two or three presses, the booster is airtight.

Genuine BMW 325i Brake Booster

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6 Brake Boosters found

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BMW 325i Brake Booster Servo Unit
Part Number: 34331162963
$847.47 MSRP: $1076.24
You Save: $228.77 (22%)
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Product Specifications
- Other Name: Brake Servo Unit; Booster Assembly, Brake Booster
- Warranty: This genuine part is guaranteed by BMW's factory warranty.
Fits the following Vehicles:
- 1992-1995 BMW 325i | Convertible(E36), Sedan(E36)
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BMW 325i Power Brake Booster
Part Number: 34336779721
$463.46 MSRP: $640.00
You Save: $176.54 (28%)
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Product Specifications
- Other Name: Brake Servo Unit; Booster Assembly, Brake Booster
- Replaces: 34-33-6-764-130
- Warranty: This genuine part is guaranteed by BMW's factory warranty.
Fits the following Vehicles:
- 2006 BMW 325i | Sedan(E90)
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BMW 325i Power Brake Booster
Part Number: 34336779682
$550.70 MSRP: $699.35
You Save: $148.65 (22%)
Ships in 1-3 Business Days
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Product Specifications
- Other Name: Brake Servo Unit; Booster Assembly, Brake Booster
- Replaces: 34-33-1-164-076, 34-33-6-756-851
- Warranty: This genuine part is guaranteed by BMW's factory warranty.
Fits the following Vehicles:
- 2001-2005 BMW 325i | Sedan M54 Engine(E46), Sedan M56 Engine(E46), Sedan(E46), Wagon M54 Engine(E46), Wagon M56 Engine(E46), Wagon(E46)
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BMW 325i Power Brake Booster
Part Number: 34331157416
Product Specifications
- Other Name: Brake Servo Unit; Brake Booster
- Replaces: 34-33-1-157-217, 34-33-1-157-199, 34-33-1-150-231, 34-33-1-154-024
- Warranty: This genuine part is guaranteed by BMW's factory warranty.
Fits the following Vehicles:
- 1987-1991 BMW 325i | Coupe(E30), Sedan(E30)
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BMW 325i Power Brake Booster
Part Number: 34331157908
Product Specifications
- Other Name: Brake Servo Unit; Brake Booster
- Replaces: 34-33-1-160-167
- Warranty: This genuine part is guaranteed by BMW's factory warranty.
Fits the following Vehicles:
- 1987-1992 BMW 325i | Convertible(E30), Coupe(E30), Sedan(E30)
View related parts
BMW 325i Power Brake Booster
Part Number: 34331162965
Product Specifications
- Other Name: Brake Servo Unit; Brake Booster
- Warranty: This genuine part is guaranteed by BMW's factory warranty.
Fits the following Vehicles:
- 1992-1995 BMW 325i | Convertible(E36), Sedan(E36)

BMW 325i Brake Booster

The BMW 325i Brake Booster provides more powerful stopping power by multiplying the pedal force. This allows drivers to slow down with less leg work. Inside many 325i models sits a vacuum-operated Brake Booster, located between the pedal and master cylinder. Its sealed chamber, valve, and diaphragm convert the pressure difference between engine vacuum and outside air into amplified push on the hydraulic circuit. When the pedal is moved, air enters at the back half of the shell. The vacuum at the front pulls the diaphragm forward, and the master cylinder reacts with a firmer clamp on the rotors. All the while, the driver feels a light pedal. Some 325i editions, particularly those sharing high-output steering pumps, use a hydraulic Brake Booster which stores pump pressure in an accumulator to produce the same assist even during low engine vacuum such as wide open throttle. Compared to the vacuum style, the hydraulic design provides steady boost under heavy loads, with the trade-off of hoses and fluid complexity. Whichever Brake Booster system is fitted, a healthy Brake Booster ensures that BMW braking is smooth, balanced, and full of signature BMW feel, as has been proven by BMW's recall of certain 325i cars to fix their potential booster issues.

If you are looking for OEM BMW 325i Brake Booster, we highly recommend to shop with us. Not only do we offer budget friendly prices, but we also provide fast delivery. In addition, we have a hassle-free return policy on all genuine BMW 325i Brake Booster that come backed by the manufacturer's warranty.

BMW 325i Brake Booster Parts Questions & Experts Answers

Power Brake Booster
34336779721
Q:
How to check if the brake booster is airtight on BMW 325i?
Posted by Cyndi H.
A:
Check the brake pedal reserve distance with the engine off. Start the engine with the pedal depressed; if it lowers slightly, it's normal. allow the engine to warm up and then turn the key to "OFF". Gently press the brake and if the pedal lowers initially but rises after two or three presses, the booster is airtight.
Answered by BMW Parts Specialist Chaz / Sep 19, 2024