Q: Brake booster heat questions again...

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So I'm having issues with the brakes having a slight drag with heat. Master is a new German replacement. (Second time it's replaced to verify good) booster is new aftermarket. VW added a brake booster heat shield in years after mine and I'm wondering what a brake booster would do if it's getting hot from exhaust and turbo heat. It's not extremely close but my injectors are very worn so I suspect my egt is higher than normal due to overfueling. Pulling the pedal up (unnoticeable amount) causes them to release smooth as glass but it happens again soon. Any ideas would be great. It's all 4 brakes dragging, new soft lines all around, new calipers too. My car has 255000 miles.

My last answer from someone said that it could be caliper debris. When the car is cool the brakes work fine. Cold outside, fine. Brakes drag evenly on all 4 wheels, lifting the pedal releases it. Is there something in a booster that heat can make it slightly engage? Still cant find this out.

My car has 253000 miles.
My car has a manual transmission.

Hi and thanks for your question. The brake booster is vacuum operated and only aids in the stopping force to the driver’s foot pedal. If vacuum pressure drops, then the foot pedal feels very firm, just like stepping on the brakes with the engine off. If you are having to pick up on the pedal and the brakes are fully disengaging, then check the return spring on the brake pedal. It may need to be replaced because it is causing the brake pedal to slightly apply itself with the engine running. The other thing is the brake master cylinder could be defective and causing the pressures to be applied at all times. I recommend checking the return spring on the brake pedal and replacing it if necessary. If you need further assistance, a technician from Your Mechanic can come to your location to inspect and repair your brake issues.

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