Meritor MM-2075 Maintenance Manual page 25

Condition Possible Causes
Fluid leak: Inlet fitting - Banjo connection
Thoroughly clean
area of concern to
clearly determine
Inlet fitting - Inverted flare fitting
leak point.
Crossover tube assembly
Piston seal or piston damaged
Wheel seal - not a caliper leak
Axle seal- not a caliper leak
Soft pedal Leak in system
Brake fluid degradation and excessive
moisture in the system can form a
steam pocket under heavy braking
Air in hydraulic system
Weak brake hose that expands under
pressure
Master cylinder leaking or unable to
apply pressure due to seal damage
Incorrect brake pads
Hard pedal Brake booster is not operating properly Check for system for leaks or on stuck
Vacuum hose leak
(16579)
Printed in USA
Check for
Fitting not torqued to specification
Check banjo bolt, banjo bolt block and
crush washers for damage or missing
washers
Fitting not torqued to specification
Check inverted flare nut and tube flare
for damage
Check tube seat in caliper inlet port for
damage
Fitting not torqued to specification
Check inverted flare nut and tube flare
for damage
Crossover tube damaged
Check tube seat in caliper inlet port for
damage
Remove the brake pads to allow
access to the piston boots. Apply
light hand pressure to each piston
boot to detect if any fluid is present
in the piston boot. If fluid emits from
the boot, then further inspection is
required to determine the source is
piston or piston seal.
Determine if fluid is brake fluid or oil
Determine if fluid is brake fluid or oil
Check brake system for signs of
leakage
Brake fluid discoloration indicating
presence of foreign material
Check brake fluid with brake fluid test
strip to verify fluid quality
Recent brake system service -
incomplete brake bleed
Deteriorated brake fluid condition -
fluid boil
Any visual hose damage
Check master cylinder pressure output Replace master cylinder.
Verify that OEM brake pads are being
used
check valve
Inspect vacuum hose for damage or
cracks
Copyright Meritor, Inc., 2023
9 Troubleshooting
Correction
Torque to OEM specification.
Replace damage fittings.
Torque to OEM specification.
Replace damage fittings.
Replace caliper.
Torque to Meritor specification.
Replace crossover tube.
Replace crossover tube.
Replace caliper if damaged.
Service piston and seal or replace
caliper.
Service wheel seal.
Service axle seal.
Replace hardware as needed. Fill
and bleed brake system per OEM
requirements.
Replace brake fluid with OEM-
approved brake fluid.
Bleed system.
Drain system and replace with
approved fluid.
Replace defective hose.
Replace with OEM brake pads.
Replace brake booster.
Replace vacuum hose.
MM-2075 / Revised 09-23
Page 21