Mack ASET AC, Руководство по обслуживанию

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Page 372
REPAIR INSTRUCTIONS, PART 2
IN-CHASSIS
PART/COMPONENT
PROCEDURES
This section presents standalone replacement
operations which can be done in-chassis and not
involve a full engine overhaul. These operations
include Electronic Unit Pump Replacement,
Camshaft Replacement and Valve Lifter H-Ring
Installation Check. In addition, in-chassis service
procedures are included for the EECU and MASS
Flow System, the cooling system, EGR system
and VTG turbocharger.
ELECTRONIC UNIT PUMP
REPLACEMENT (IN-CHASSIS)
[221 GP]
To properly service the electronic unit pumps
(EUPs), it is essential to understand unit pump
removal, pin and tappet installation, and unit
pump installation. Each of these procedures is
covered individually.
Unit Pump Removal
When it is necessary to remove more than one
EUP, the removed EUPs must be paint-marked
with the cylinder number, and reinstalled at their
original locations. This will eliminate any need to
reprogram the EUP information. If a new or
remanufactured EUP is installed, reprogramming
must be performed as described at the
conclusion of the EUP installation section.
1. Remove both the EGR hot and cool tubes
from the right side of the engine (AC engine
only).
2. Remove the heat shields.
3. Clean the EUP and cylinder block around
the EUP to ensure that no debris enters the
engine during EUP removal.
To avoid engine damage due to debris entering
EUP bores of the cylinder block, step 2 MUST be
followed.
4. On chassis with inlet manifold-mounted fuel
filters, remove both the inlet and outlet fuel
hoses from the secondary fuel filter. This
allows additional fuel to drain from the hose,
through the cylinder block, and out of the
internal passages.
On chassis with remote-mounted fuel filters,
remove the fuel hose from the cylinder block
fuel-inlet fitting, which is behind the EECU at
the top. This allows additional fuel to drain
through the cylinder block and out of the
internal passages.
5. Place a drain pan beneath the right side of
the engine. Remove the fuel-outlet fitting
from the cylinder block fuel return gallery
above the air compressor. This allows fuel to
drain from the internal passages.
To ensure that minimal fuel enters the crankcase
oil during EUP removal, steps 3 and 4 MUST be
followed. To avoid fuel spillage, do not crank the
engine with the starter at any time during EUP
removal or replacement.
6. Remove the injection tube.
7. Remove the harness wire connections at the
EUP terminals.
8. Remove the inboard EUP mounting screw
completely.
9. Loosen the outboard EUP mounting screw
and back it out 1/2 inch (12 mm).
10. Insert screwdrivers under the bolt bosses
(front and rear) and pry until the EUP comes
out against the screw head. (The EUP may
spring out against the screw head.)
The EUP spring may be preloaded with
significant spring tension, depending upon
cam lobe position. To avoid injury from the
EUP springing outward, steps 7–9 must be
followed.
11. Remove the outboard EUP screw
completely and remove the EUP from the
cylinder block. Place the EUP in a clean
area and cover it to prevent entry of dirt and
other contaminants.
5-111.bk Page 372 Monday, July 10, 2006 2:26 PM