TROUBLESHOOTING
Page 119
5. Check the valve actuator pin located in the
valve yoke to ensure that the pin is not bent
or damaged. The pin should not stick in the
yoke at any point in its travel. There should
be no signs of “mushrooming” or other
damage where the plunger contacts the
head of the actuating pin.
FINAL TEST
1. Install the engine brake components on the
engine and adjust the brake piston and valve
lash to the proper settings shown in the table
on page 114.
After installing the rocker assemblies and
adjusting engine brake and exhaust valve
lash, start the engine and run at an idle for
several minutes.
The engine brake requires a minimum oil
pressure of 25 psi. When troubleshooting engine
brake operation, it is desirable to do any test
procedures with the engine operating at idle.
Make sure engine oil pressure at idle is sufficient
to support the engine brake minimum oil pressure
requirement. If engine oil pressure is not
sufficient at idle, increase engine speed until the
minimum oil pressure requirement is obtained.
2. Check for oil leaks at the oil supply screen
and solenoid valve. If leakage is noticed,
shut the engine down and repair the leaks.
Some leakage will be seen at the hydraulic
actuator plunger and the control piston cap. This
leakage is normal. Excessive leakage, however,
must be investigated.
3. After these final inspections and necessary
repairs, install the cylinder head covers.
4. Test drive the vehicle to verify any problems
have been corrected.
ENGINE BRAKE TESTS
(J-TECH™)
The ASET™ engines may be equipped with
either a MACK PowerLeash™ engine brake or a
J-Tech™ engine brake. The test procedures in
this section apply only to the J-Tech™ engine
brake.
Operational Tests
Before beginning the troubleshooting procedures,
try to determine the exact nature of the problem.
Talk to the driver, owner and/or mechanic to
pinpoint the complaint or problem. The following
checks may be helpful in trying to determine the
nature of the problem.
BEFORE STARTING THE ENGINE
If there is a report of engine or engine brake
noise, remove the cylinder head covers to
determine the cause. Check the following items:
1. Check for loose or broken components.
2. Check and verify valve and engine brake
plunger lash settings.
3. Check for bent push rods. If bent push rods
are found, check for possible bent valves,
and if the engine is equipped with ceramic
roller lifters, check for broken ceramic
rollers. Possible causes of bent valves or
push rods could be:
Engine overspeeding — Usually several
valves are affected.
One bent exhaust valve or push rod at a
single cylinder — The problem may be a
stuck master or slave piston, damaged slave
piston adjusting screw (reset screw) or
excessive oil pressure.
5-111.bk Page 119 Monday, July 10, 2006 2:26 PM
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