Question about 1999 Ford Explorer

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Brake booster Gone out

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What you would want to try on the booster is a non-corrosive testing substance like water vapor or propane gas. I'll explain. Years ago propane gas was used to set the idle on pollution controlled engines so it is safe to draw into your motor. It will change the RPM of your running engine. Water vapor or spray will do the same thing but may not flow through the booster as easily. If the RPM does not change, the booster is not leaking.

The booster has a rubber diaphragm and if the booster is still good you would not want to ruin it with carb spray or anything else as a tester.

The supply line to the booster has a plastic fitting which should also be checked for leaks.

Should the booster be bad, it is easily changed on most models. If you can slide the Master cylinder away from the Booster while leaving the brakelines attached, you simply need to disconnect the plunger and any connections from the brake pedal. Remove the booster and slide in the new one.

There is also the chance that the Master cylinder is bad. If your fluid bypasses the seals in the Master cylinder you will not get pressure to the brakelines, regardless if you have a booster or not.

Posted on Mar 27, 2014


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I have replaced 3 of 4 disc calipers on my pt cruiser. I have bleed brakes on all 4 calipers and have good brake pedal until I start the car.When I start the car the brake pedal goes to the floor.

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