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Kyle
Kyle, Ford Technician
Category: Ford
Satisfied Customers: 212
Experience:  Ford certified - Diesel, gas, electrical, a/c, man trans, diff, suspension. Specialize in Electrical
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94 e-350 van diesel..problem pedal is dropping..master cylinder..pads

Customer Question

94 e-350 van diesel dually - brake problem pedal is dropping while running, changed master cylinder and tested it by blocking it off. replace both front calipers, wheel cylinders , pads and shoes, did a brake line test. what could be causing this
Submitted: 7 years ago.
Category: Ford
Expert:  Kyle replied 7 years ago.
Hello and thank you for asking your question on just answer. There are a few things that can cause this type of problem. Of course if there is a fluid leak somewhere,If there is air in the hydraulic system, If the master cylinder is bleeding down/bypassing internally, or if there is a faulty dump valve in the ABS Hydraulic Control Unit. If the dump valve is faulty, then any brake pedal pressure will bleed down into the fluid chXXXXX XXXXXnked to the faulty dump valve. I have seen this before. If this is the problem, then you will need to replace the ABS Hydraulic Control Unit and it will need to be bled with a scan tool and then the entire brake system will need to be bled as well. I hope this helps you with your repair.

Thank You,

Kyle.

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Customer: replied 7 years ago.
we have bypassed the abs valve and it still bleeds down, we capped off the master and checked rears good pedal it seems like just the fronts only,
Expert:  Kyle replied 7 years ago.
This is almost always caused by the abs valve or the master cylinder. I recommend bleeding the entire system again. Also check for any seeping around the brake hoses at the calipers and at the metal line connection. Check for any brake fluid seeping around the brake pistons. I also recommend measuring the brake rotor thickness and brake pad thickness, Sometimes severely worn rotors and pads can cause a very low pedal and make the pedal feel like it is falling.

Thank You,

Kyle.

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Customer: replied 7 years ago.
it did not take care of the problem. put a gauge on the calipers and the pressure was not dropping it was because of the brake booster