My car requires a second master cylinder replacement for the second time within three years. I don't understand it. The first failure occurred in 2015, right after my 60000 service was completed. The second failure began displaying symptoms in November 2016. The symptoms are these. When pressing the brake to slow down or stop, the car will begin slowing down, while that is happening, the car will abruptly stop as if I slammed on my brakes. This happens at any speed, with any light, moderate, or heavy pressure on the brake pedal. It's as if an extra, nearly uncontrollable pressure is applied during my stops. Nissan says that it's not a defect, yet this is the second master cylinder failure, and it will cost over $900.00 to replace it. Please help.
My car has 80000 miles.
My car has an automatic transmission.
Hi there - I believe your master cylinder failure is being misdiagnosed. I believe the problem is with the brake booster - one of the control valves (vacuum?) to be specific. If this valve malfunctions, it could allow much more "braking assist pressure" to be applied than you are providing with your foot. This would cause the "sudden stops" behavior you describe. For assistance, I recommend a brake system inspection performed by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, and give you an accurate assessment of damage and cost estimate for repairs.
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