Page 78
TROUBLESHOOTING
ENGINE BRAKE TESTS
(MACK E-TECH™ ENGINE
WITH 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 engine covers to determine the
cause.
1. Check for broken or loose parts.
2. Check valve and engine brake lash settings.
3. Check for possible bent valves or push rods.
Possible causes of bent valves or push rods
could be:
Engine overspeeding — Usually several
valves are affected.
One bent exhaust valve or push rod — This
indicates a possible problem with a stuck
master or slave piston, damaged slave
piston adjusting screw (reset screw) or
excessive oil pressure. See the Table on
page 81 for oil pressure requirements.
A bent exhaust valve may be caused by the
valve stem stuck in its guide, bad yoke
adjustment, or broken or weak valve
springs.
TEST DRIVE
1. Test drive the vehicle and measure intake
manifold boost pressure while operating the
engine brake. Refer to the Table on page 78
for boost pressures.
RETARDING BOOST PRESSURES (PSI)
MACK E7 300A E-Tech™ Engine (Schwitzer S-300
Pre-12/99 — S-400S Post 12/99 Turbo)
2100 rpm — 18 psi Boost
1900 rpm — 17 psi Boost
1700 rpm — 16 psi Boost
1500 rpm — 14 psi Boost
1300 rpm — 10 psi Boost
1100 rpm — 8 psi Boost
MACK EM7 275, 300 and E7 310/330 E-Tech™ Engines
(Schwitzer S-300 Pre-12/99 — S-400S Post 12/99
Turbo)
2100 rpm — 19 psi Boost
1900 rpm — 18 psi Boost
1700 rpm — 18 psi Boost
1500 rpm — 16 psi Boost
1300 rpm — 11 psi Boost
1100 rpm — 8 psi Boost
MACK E7 300, 330/350, 350, 355/380, 400 E-Tech™
Engines (Schwitzer S-300 Pre-12/99 — S-400S Post
12/99 Turbo)
2100 rpm — 18 psi Boost
1900 rpm — 18 psi Boost
1700 rpm — 17 psi Boost
1500 rpm — 14 psi Boost
1300 rpm — 10 psi Boost
1100 rpm — 8 psi Boost
MACK E7 427, 460 E-Tech™ Engines (Schwitzer S-400
Pre-12/99 — S-400S Post 12/99 Turbo)
2100 rpm — 17 psi Boost
1900 rpm — 15 psi Boost
1700 rpm — 14 psi Boost
1500 rpm — 11 psi Boost
1300 rpm — 8 psi Boost
1100 rpm — 6 psi Boost
5_106_00.bk Page 78 Friday, August 4, 2000 11:17 AM
BDC for engine manuals and specs
