Hino 600, Workshop Manual, Page: 266 / 451

SERVICE BRAKE (HYDRAULIC BRAKE) BR02–22
TROUBLESHOOTING
EN1680102F300001
Symptom Possible cause Remedy/Prevention
Excessive Pedal Effort Pads worn below minimum thickness Install new pads.
Faded, overheated condition, glazed
pads, blued or heat-checked rotors Replace the rotor and/or reface pads if
sufficient lining remains.
Grease, oil and/or brake fluid on linings Install new pads in the axle sets.
Seized or frozen pistons Disassemble the calipers and free pis-
tons, or replace the caliper.
Pedal Pulsation (Brake Roughness
or Chatter) Excessive lateral runout of brake rotor Check with a dial indicator. Install a
new rotor if the runout exceeds the
maximum specified.
Excessive out-of-parallelism of brake
rotor Check the parallelism or rotor thick-
ness variation with a micrometer.
Resurface the rotor or install a new
rotor if the parallelism exceeds the
maximum allowed.
Loose or worn steering or suspension
parts Replace the parts and realign.
Excessive front bearing clearance Readjust the bearing to specifications.
Vehicle Pulls to One Side Brake fluid, oil and/or grease on linings Install new pads in the axle sets.
Unmatched linings, uneven lining
wear, distorted pads Install new pads in the axle sets.
Rough rotor surfaces on one rotor Resurface or replace the rotor in the
axle sets.
Seized or frozen pistons Disassemble the caliper and repair or
replace.
Loose caliper mounting bolts Tighten to specifications.
Uneven tire pressure, tread wear or
size, right to left Equalize to the recommended pres-
sures. Install the correct size tires with
good tread.
Excessive rotor parallelism or runout Resurface or replace the rotor.
Restricted hose or line Examine the hoses and lines, and
replace as necessary.
Front end out of alignment Reset the alignment.
Leaky Caliper Cylinder bore surface scored or cor-
roded Disassemble the calipers, clean the
bore and replace the seals and boots.
Caliper piston seal damaged or worn Disassemble the calipers and install
new seals and boots.
Caliper piston damaged Replace the piston.