0324406 JOHNSON BASE, Air silencer

Introduction
This Special Instruction details instructions to change the present unit injector hydraulic pump for a HEP pump that adds an opposing tapered roller bearing The additional bearing counters gear torsional loads that can lift the rollers off the race and lead to high contact stresses. The new pump design is longer than the current pump. Certain applications will require replacing additional components due to the longer HEP pump. A new high-pressure oil line and adapter are required to connect the pump to the cylinder head.Safety Information
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids.Refer to Special Publication, NENG2500, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat products.Dispose of all fluids according to local regulations and mandates.
Do not allow dirt to enter the fuel system. Thoroughly clean the area around a fuel system component that will be disconnected. Fit a suitable cover over disconnected fuel system component.Do not allow dirt to enter the fuel system. Thoroughly clean the area around a fuel system component that will be disconnected. Fit a suitable cover over disconnected fuel system component.
Keep all parts clean from contaminants.Contaminants may cause rapid wear and shortened component life.Keep all parts clean from contaminants.Contaminants may cause rapid wear and shortened component life.
Do not operate or work on this engine unless you have read and understand the instructions and warnings in the Operation and Maintenance Manual. Failure to follow the instructions or heed the warnings could result in injury or death. Contact any Caterpillar dealer for replacement manuals. Proper care is your responsibility.
Fuel leaked or spilled onto hot surfaces or electrical components can cause a fire. Clean up fuel spills immediately.
Cylinder Head Rework Procedure
Note: There is a potential for interference between the new Dual Tapered Roller Bearing (DTRB) Hydraulic Electronic Unit Injector (HEUI) pump and the cylinder head intake flange on C7 ACERT engines built before KHX47176. Engines with build dates after the date above have cylinder heads that do not present this condition. For engines with build dates prior to the date above go to the next step.
Illustration 1 g03389031Test fitting the pump for clearance at location (1) is recommended in Illustration 1. If the new DTRB (HEUI) pump is in contact with the cylinder head after mounting bolts are snugged, modify the cylinder head per the following instructions.Note: Do not modify the HEUI pump. Removing material from the HEUI pump may create an unsafe condition.
Remove HEUI pump and apply suitable protection to the front cover opening and any open fluid lines and fittings to prevent debris entry during this process. Removing the inlet cover group is not required to perform this procedure. If the intake air lines have been disconnected, protect the opening from debris entry.
Illustration 2 g03395855
Scribe a line (2), parallel to the cylinder head top surface, at the center of the port plug. Refer to Illustration 2.
Scribe a line along the edge of the inlet air cover group at edge (3). Refer to Illustration 2.
Scribe a line (4) parallel to line (2) the distance of 48.7 mm (1.9 inch) from line (2) as shown in Illustration 2.