Jim Grant's Tech Tips
96
Ford Windstar, No Brakes
Q: I have a ‘96 Ford Windstar. We installed new calipers,
rotors, brake pads and a master cylinder, (without traction control but
does have Anti-Lock Brakes (ABS). None of the brake warning lights are
on to indicate a problem with the Anti-Lock Brakes. The problem is that
the van will not stop. What can be the problem?..... Desperate.
A: Was
your brake problem present before or did it occur after the brake work
was performed? My first impression is the possibility of air in the hydraulic
brake system. Vehicles equipped with ABS require a specific procedure
to properly bleed the air from the brake system. Air in the system will
cause a very low and spongy brake pedal. Also something as simple as the
need for rear brake adjustment can create a complaint such as yours. The
braking systems on many of today’s vehicles are what is called a diagonal
system. This means that the right rear brake and the left front share
the same hydraulic line while the left rear and the right front share
the other. If the rear brakes are too far out of adjustment the affect
will be a very low brake and poor stopping ability. I’ve seen vehicles
that have received a replacement master cylinder, when the only problem
was incorrectly adjusted rear brakes.
If you’re sure the brake work and bleeding of the hydraulic
brake system has been performed correctly then the ABS does come into
question. The valving inside an ABS unit can leak internally presenting
a brake pedal problem that is often confused with a faulty master cylinder.
To diagnose this condition requires isolating the ABS system to check
for internal leakage.
With the complexity of today’s vehicle’s you may want to
have your brake problem checked out by a technician who has a thorough
understanding of today’s braking systems.
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