My MCS r56 break stiff , very hard. My car doesn't seem stop when i break. If I drive normal is working properly. But if in bumper to bumper traffic.... my break very stiff. Is that cuz of break vacuum pump?

Thank you.

 

It could be your vacuum pump. It could also be the line from the vacuum pump to the brake booster. This line is hard, black plastic, comes off of the top of the vacuum pump, and if it is disconnected or has a hole in it will result in the symptoms you describe.

Keep us posted. Good luck.

 

How can I do the vacuum pump test? If it properly works or not.

Thanks

 

Just disconnect the line and press on the brakes, if it feels the same, it might be the pump or lines. I would make sure the pump is not clogged in the feed line. Also check those hard lines.

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