Mack ASET AC Service Manual Download

Page: 137 / 536

Page 124

TROUBLESHOOTING

8. Compress the slave piston springs down

until the retainer is about 1/32 inch (1 mm)
below the retaining ring groove. Reinstall the
retaining ring. Be sure the retaining ring is
fully seated in the groove.

9. Remove the clamp fixture slowly to ensure

proper seating of the retaining ring.

FINAL TEST

Follow the instructions in the installation manual
to reassemble the J-Tech™ housings. Install a

new

oil supply seal ring.

1. Install the housings on the engine. Check

the valve yoke clearance and valve lash for
proper adjustment and then adjust the slave
piston clearance to the proper settings
shown in the table on page 122.

2. Before installing the engine covers, start the

engine and allow it to warm up for a few
minutes.

3. Depress the solenoid valve several times to

fill the housing with engine oil.

Engine brakes require a minimum oil pressure for
operation. If there is less than minimum at idle,
run the engine at higher RPM (800–900) when
making checks.

4. Check for oil leaks at the oil supply screw,

solenoid valve and housing pipe plugs. If
leakage is noticed, shut down the engine
and repair the leaks.

Some leakage will be seen at the master piston,
slave piston and control valves. This is normal.
Excessive leakage must be investigated (see
“J-Tech™ Checks (Hydraulic/Mechanical)”).

5. After final inspection and necessary repair,

shut down the engine and replace the
gaskets and covers.

6. Test drive the vehicle following the Test

Drive procedures (covered earlier) to verify
corrective action.

J-Tech™ Troubleshooting Guide

Following is a list of problem conditions showing
the probable causes and subsequent corrections.

ENGINE FAILS TO START OR STARTS AND
RUNS ONLY ON THREE (3) CYLINDERS

앫

Solenoid valve stuck in ON position

—

Ensure that electrical current is off to the
engine brake units. If the solenoid valve
remains on (cap down) with current off,
replace the solenoid valve.

ENGINE BRAKE WILL NOT OPERATE

앫

Blown fuse, open electrical leads

— Look

for a short circuit in the wiring. Replace any
broken, brittle or chafed wires. Check
solenoid tab for signs of shorting and
replace if necessary. Replace 10 amp fuse.

앫

On/Off switch, clutch switch or
multi-position switch out of adjustment
or defective

— Use a volt/ohmmeter to

make certain that there is electrical voltage
available at both terminals of each switch.
Readjust if needed or replace if voltage will
not pass through switch.

Do not touch electrical connection when
system is energized.

앫

Mounting bracket-to-rocker shaft
mounting screws loose or missing

—

Inspect for missing or loose mounting
bracket-to-rocker shaft screws. Repair as
required.

앫

Incorrect electrical power source

—

Check that the supply voltage is the
appropriate voltage. Recommended power
source is from the key switch ON position.
Ensure that power is not taken from a
source with an additional on/off switch, i.e.,
light switch. See solenoid specifications in
the table on page 121. Make sure wiring is in
accordance with MACK wiring instructions.

앫

Low engine oil pressure

— Determine oil

pressure at engine brakes (solenoid valve
and control valve). If oil pressure is below
specification, the engine should be repaired
in accordance with MACK procedures.

Mack ASET AC, Service Manual

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