User Manual

200 BENCH PROCEDURES
Page 5-67
[222 KG] INJECTOR NOZZLES
1991 and later MACK E7 engines require
different fuel injection nozzles, nozzle holders
and nozzle holder assemblies than previous E7
engines.
These later nozzles (with eight spray holes) are a
Valve Covering Orifice (VCO) configuration and
are hydroground for proper fuel flow and
atomization.
Nozzles used for 1989/1990 MACK E7
production engine models feature six spray holes
and are not hydroground.
These parts are not interchangeable with eight-
spray-hole nozzles used in 1991 and later
engines. Refer to the following engine tune-up
publications for pertinent E7 specifications.
5-301............................. 1989
5-302............................. 1990
5-303............................. 1991
5-304............................. 1992
5-305............................. 1993
5-306............................. 1994
5-307............................. 1995
5-308.................... 1996/1997
Nozzle Cleaning
When servicing nozzle holder assemblies,
cleaning of nozzle tips may be necessary.
Special care must be taken when cleaning nozzle
tips to avoid damaging nozzle spray holes.
앫 Preferred cleaning method: ultrasonic
cleaning
앫 Acceptable cleaning method: brass brush/
wire wheel
ULTRASONIC CLEANING METHOD
Ultrasonic cleaning units such as J 29653-A, use
sound waves or mechanical vibrations,
approximately 55,000 cycles per second above
human hearing range. Sound waves are
generated by the transducer, which changes
high-frequency electrical energy into mechanical
energy.
The nozzles will be damaged if a steel-wire wheel
is used for cleaning. Damage can also occur if an
improper size and/or speed of brass-wire wheel is
used.
5-101.bk Page 67 Friday, March 17, 2006 11:05 AM