Housings For Reman Engines
Oil pumps on Caterpillar engine models 3408 (S/N 28V1-Up), 3406B (S/N 3ZJ1-Up), C-15 (S/N EGH1-Up, MBN1-Up, 6NZ1-Up and 9NZ1-Up) C-16 (S/N 7CZ1-Up), C-18 (S/N CJP1-Up, MDP1-Up, MEP1-Up) and C15 (S/N SDP1-Up, BXS1-Up, MXS1-Up and NXS1-Up) may be assembled with two different types of housings.

One of the housings has a drilled oil gallery (see Figure 1) and the other housing does not (see Figure 2). The housing with the drilled oil gallery allows the pump to send oil to a passage that allows lube for an idler gear in the gear train.

For 3406 pumps with plugged passages, a housing with a drilled oil passage is not needed. These pumps can be remanufactured using either housing. However, if you receive a 3406 oil pump with a housing that has a drilled oil gallery, then you must also use the 2S-7905 pipe plug. If the plug is not in place, the pump will move oil, but the pressure is lost because the oil is not diverted to the proper oil gallery. For 3408/3412 oil pumps with open oil passages, use a housing with a drilled oil gallery. These pumps must be manufactured with the housing that has the 2S-7905 pipe plug installed.

Revised Fuel Level Sending Unit
Effective April 30, 2007, Mack implemented a revised fuel level sending unit (Part No. 16MB421M) into production on GU, CTP and CT model chassis to address issues concerning the fuel cap tether chain entangling with the float arm. The revised sending unit, which replaces the old sending unit (Part No. 16MB419M), is rotated 90 degrees on the mounting flange so that the float arm is positioned away from the fuel tank cap when installed on the fuel tank.

Leak Testing Oil Coolers
A high percentage of the OR-9056 oil cooler core assemblies on Caterpillar engines that are returned for leaks will pass the leak test in Special Instruction REHS1758. As of May 1, 2007, all OR-9056 oil cooler core assemblies that are returned will be leak tested. All assemblies that pass the leak test will be returned to the dealer and the claim will be denied.

Special Instruction REHS1758, Test Procedure For Brazed And Rubber End Sheet Oil Cooler, provides technicians with a listing of tooling and the steps that are required to properly test for leaks in oil coolers that have brazed or rubber end sheets.

Diagnosing Turbocharged Diesel Engines
BorgWarner Turbo & Emissions Systems offer possible causes for several common problems with turbocharged diesel engines.

Oil leakage at the turbine end can be caused by a dirty air filtration system, damaged turbocharger bearings, foreign object damage to the compressor or turbine wheel, a damaged turbine housing or flap or insufficient oil supply to the turbocharger.

If your customer complains of insufficient power or that the boost pressure is too low, possible causes include:

  • A dirty air filtration system;
  • A distorted or leaking intake or pressure hose;
  • Excessive flow resistance in the exhaust system or leakage upstream of the turbine;
  • A defective or incorrectly adjusted fuel system/injection feed system;
  • Worn valve guide, piston rings, engine or cylinder liners;
  • A dirty compressor or clogged intercooler;
  • A boost pressure control swing valve or poppet valve that does not close properly;
  • A defective or ruptured pipe hose assembly to the actuator valve;
  • A damaged turbocharger bearing;
  • Foreign object damage to the compressor or turbine wheel;
  • Missing or loose gaskets in the engine air collector/cleaner;
  • A damaged turbine housing or flap; or
  • An insufficient oil supply to the turbocharger.

If the boost pressure is too high, check to see if the intake or pressure hose is distorted or leaking, the fuel system/injection feed system is defective or incorrectly adjusted, the boost pressure control swing valve/poppet valve does not open or the pipe or hose assembly to the actuator valve is defective or ruptured.

The following is a recent recall made by the National Highway Traffic Safety Administration:

  • Freightliner is recalling 11,359 Model Year 2005 to 2008 Thomas Built Saf-T-Liner C2 school buses. The external warning lights may stop functioning unexpectedly if the front entrance door closes without the driver’s input. Freightliner will notify owners and repair the buses.

Air Compressor Coolant Return Line
The air compressor coolant return line on Mack US04 emission compliant MP7 engines is clamped at multiple locations along the length of the line. On the right-hand side of the engine, approximately two inches forward of the flywheel housing/timing gear mounting plate, the line is clamped with a two-piece stand-off bracket (Part No. 20747032), which is secured to the oil cooler cover by a M6 x 1.0 capscrew (Part No. 965176). The capscrew does not include a locking feature (see Figure 3).

If you have to remove this capscrew or if you find it loose during the course of an engine repair, apply a small drop of Loctite 242 to the thread and the capscrew. Tighten the capscrew to 89 lb.-in. when reinstalled.

Note: Do not overtighten the capscrew. Doing so will strip the threads in the aluminum cover.

Connector Orientation
Moisture infiltration into the 16-pin vehicle interface connector on Mack CXP and CTP models because of incorrect connector orientation, missing connector seals or seal plugs can result in multiple faults being logged by the engine, vehicle and instrument cluster electronic control units.

The faults usually include MID 144 PSID 200 FMI 9 and MID 140 PSID 200 FMI 9, “Loss of Communication with Engine ECU.”

This connector is located on the inside of the left-hand frame rail, toward the front of the chassis. If you find multiple fault codes, disconnect the connector and clean and dry it.

Also check the integrity of the wire seals and make sure that the seal plugs (Part Nos. 20708413 for the engine side of the connector and 969AM8 for the chassis side of the connector) on unused pin cavities are in place.

After reconnecting, secure the connector to the inside of the frame rail with tie wraps and be sure it is oriented horizontally with the harness wires facing front to back, not up and down (see Figure 4).

Air System Freeze-Ups
Bendix released the following possible causes of air system freeze-ups and the corrective actions to be taken:

  • For excessive leakage, check the compressor unloaders, governor and air dryer check valve.
  • For kinked, broken or a frozen unloader line, replace or repair as needed.
  • Test the heater if it is not working properly. The heater cannot be tested at room temperature. The thermostat in the end cover controls the heater. The cover must be cooled to below 40˚ F – it will cut out above 85˚ F. Check the fuse and test the thermostat with an ohmmeter. Refer to the
    appropriate service data sheets.
  • The power might not reach the end cover. Check for power to the end cover and for a good ground connection. Refer to service data sheets for the correct resistance valves.
  • Dryer service might be overdue. In this case, replace the cartridge.

Revised Exhaust Heat Shield
On certain Mack CHN Rawhide models, cracks might occur in the exhaust heat shield around the mounting bolt holes. If you encounter this, a revised heat shield (Part No. 13ME548M2) is available.

The heat shield uses six additional mounting holes and requires three additional clamps (Part No. 37AX578) that must be used under the heads of each of the mounting screws.

In addition to the revised exhaust heat shield, a rubber bumper (Part No. 104AX578) and bumper mounting bracket (Part No. 8ME3793M), which mounts to the lower exhaust pipe bracket, has been developed. The bumper prevents excessive heat shield vibration. If you replace the existing exhaust heat shield, also install the rubber bumper and bumper mounting bracket.

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