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Brake Pedal becomes rock hard sometimes.

2010 BMW 320i

Following recent replacement of Rocker Cover and Gasket by BMW, the Brake Pedal sometimes becomes rock hard after the engine is not working for a number of hours. What is the problem?

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Hi,

Check if the vacuum brake pump is connected properly or is even working

Park the car and turn off the engine.

Pump the brake pedal five or six times

Start the engine, and keep your foot pushing down on the pedal. Check what happens to the pedal.

With the engine running, the engine sucks the air out of the brake booster, restoring the vacuum. Normally, the pedal will drop towards the floor with your foot applying light and steady pressure on it.

If the pedal pushes back against your foot, then there is a problem. This could be a blocked vacuum hose, a leak in the vacuum hose, or a leak in the brake booster check valve.

Given that it happens after the engine has been idle for some time, inspect the check valve for leaks.

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pythagorasgp , This is what a lot of the BMW forums are saying, Very common issue, the culprit is usually a leaking check valve. I also found a good link for you to read through that goes in depth of the issue even from earlier models.

http://www.e90post.com/forums/showthread...

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If it's very cold by you, sometimes ice can develop in the hose supplying vacuum to the brake booster (or check valve). The water could possibly entered the system during your recent service. Just a possibility.

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Most of the car's brakes are assisted by vacuum. If you pump the brakes off your car, you get to find a normal pump, and they in due course of time hardens as the vacuum reservoir gets exhausted. Now if your car is being used for weeks together, the vacuum might recede as the system isn't designed to hold the vacuum for long, and that’s why you tend to get the hard pedal feel. You can test this hypothesis easily by turning off the car and pumping the brakes.

The probable reasons and frequent solutions to get rid of the hard brake pedal are:

Vacuum or lack of vacuum pressure is the most common cause of a hard brake pedal, and therefore, it is the foremost thing to look at when the brake pedal becomes rock hard. Another possible reason for a hard pedal could be the combination valve and in particular the Pressure Differential Valve within it. A thorough inspection of the whole system should help you identify such underlying issues of a hard brake pedal.

If you are completely unaware and do not know how to take the correct action, engage a professional mechanic at Eurobahn BMW MINI Mercedes-Benz Audi of Greensboro.

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댓글:

Could putting on new breaks and caliper-Core be the reason why my breaks are hard ?

Do they just need breaking in

Could the lack of vacuum also prevent the egr valve correctly opening and cause an insufficient flow code?

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