Revised Transmission Heat Shield
Mack offers a revised transmission heat shield for CXP and CTP model chassis equipped with a T300 transmission and dual exhaust. This revised heat shield has been developed to address issues with the previous heat shield breaking prematurely in service.
The mounting legs of the revised heat shield are larger, 4.5mm x 30mm as opposed to 1.6mm x 22mm mounting legs on the previous heat shield (see figure 1).
If you encounter a broken transmission heat shield, the revised heat shield should be used as a service replacement. Part No. 71RC51AM is the heat shield for T300 series long-compound transmissions. It replaces Part No. 71RC51M. Part No. 71RC52AM is the replacement for Part No. 71RC52M for T300 series short-compound transmissions.
Installing Severe-Service Quik-Align
Use the following procedure to assist in installing the Severe Service Quik-Align Pivot Bolt Kit No. 60632-015 for Hendrickson PRIMAAX rear air suspensions.
Disassembly
- Chock the wheels.
- Support the frame of the vehicles at ride height.
- Disconnect the height control linkage assembly from the height control valve arm. Lower the leveling arm to exhaust the air in the air spring and deflate the air suspension.
- Support the pinion of the axle being serviced so that the axle will not shift or rotate during service.
- Before loosening the existing Quik-Align collars, mark the position of the Quik-Align eccentric collars on the frame hangers. This will allow the new components to be installed in the same orientation, preserving the existing alignment of the axle.
- Remove and discard the existing 1-inch pivot bolt, locknut, washers and Quik-Align collars (see figure 2).assembly
- Verify the new fasteners will pass through the existing inner metal of the pivot bushing (see figure 3). If the fastener will not pass through, resizing of the inner metal of the pivot bushing to 1-/ inch may be required.
- Assemble the new severe service bolts, washers, Quik-Align collars and locknuts (see figure 4). Ensure that the Quik-Align eccentric collar is installed on the outboard side of the frame hanger.
- Tighten the locknut until the Quik-Align components are snug against the frame hanger, but the Quik-Align eccentric collars still can be rotated.
- Adjust the Quik-Align eccentric collars to the same orientation as the eccentric collars that were removed. This will return the axle to the pre-disassembly alignment.
- Torque the locknut to final torque using one of the following methods:
- Using a torque wrench or torque multiplier, tighten the locknut to 1200 to 1400 ft.-lbs.
- Using the torque and tighten method, pre-torque the locknuts to 190 to 210 ft.-lbs. after the pre-torque has been applied, tighten the locknut an additional 3/4 of a turn.
- Inflate the suspension by connecting the height control valve linkage to the height control valve arm. Verify the air springs inflate uniformly without binding.
- Remove the support from the axle pinion.
- Remove the frame supports.
- Verify proper ride height adjustment.
- Remove the wheel chocks.
Exhaust Temperature Sensor
A revised exhaust temperature sensor (Part No. 64MT380M) is available for Mack CXP and CTP models. This revised sensor utilizes a sealed connector, and was developed to address concerns with inaccurate temperature readings, especially after power washing the vehicle.
It is recommended that this revised sensor be used as the replacement for any complaints of inaccurate exhaust temperature readings.
When replacing an existing exhaust temperature sensor (Part No. 64MT377M or 64MT377AM) on a vehicle manufactured prior to March 2007, a jumper harness (Part No. 41MR31639M) will be required in order to connect the sensor to the existing dash front harness (see figure 5).
Locate the 12-pin dash front harness connector, and then remove the existing exhaust temperature sensor wire from terminals M and F. Connect jumper harness wire HB4-0.8 to terminal M and wire HB5-0.8 to terminal F of the 12-pin dash harness connector. Connect the opposite end of the jumper harness to the exhaust temperature sensor (see figure 6).
When installing the exhaust temperature sensor in the exhaust pipe, tighten the sensor to 60 lb.-in.
Cold Weather Tips
Following are cold weather tips to help protect your customers’ vehicles from air system freeze-ups, courtesy of Bendix Commercial Vehicle Systems.
Discharge Line
The discharge line should slope downward from the compressor discharge port without forming water traps, kinks or restrictions. If it crosses over from one side of the frame rail to the other, it should occur as close to the compressor as possible. Avoid fitting extensions. Recommended discharge line lengths and inside diameters depend on vehicle application.
The maximum discharge line length for typical pickup and delivery, school bus and line-haul applications is 16 feet. If the line length is between 6 feet and 9 feet 5 inches, you need an inner-diameter minimum of 1/2 inch. For line lengths of 9 feet 5 inches to 12 feet, the minimum inner diameter is 1/2 inch and the last three feet, including the fitting at the end of the discharge line, must be insulated with 1/2-inch thick closed cell polyethylene pipe insulation. Line lengths between 12 feet and 16 feet need an iner-diameter minimum of 5/8 inch and also need insulation.
The maximum discharge length for severe-service/high-duty cycle vehicles is 16 feet. Line lengths between 10 feet and 16 feet need inner-diameter minimums of 1/2 inch.
Air & Electrical Lines
Additionally, Bendix offers these tips for preventing air lines from freezing and how to thaw them in the event they do freeze.
- Check the air dryer for proper operation, changing the desiccant cartridge and purge valve as necessary.
- Thaw frozen air lines and valves by placing the vehicle in a warmed building. This is the only method for thawing that will not cause damage to the air system or its components.
- Use dummy hose couplings on the tractor and trailer.
- Check for drooping air lines, which could form water traps.
- Do not apply an open flame to air lines or valves. This is unsafe and can result in a vehicle fire. It also can damage the valve and melt air lines.
- Do not pour fluids into air lines or glad hands. Certain fluids can cause immediate and severe damage to rubber components. Even methanol, which is used in alcohol evaporators and injectors, should not be poured into air lines. Fluids poured into the system wash lubricants out of the valves, collect in brake chambers and valves and can cause malfunction. Loss of lubricant can affect valve operating characteristics, accelerate wear and cause premature replacement.
- Do not immediately park a vehicle outside after thawing the air system indoors. Condensation will form in the system and refreeze. Place the vehicle in operation when it is removed to the outdoors.
Lower Radiator Hose
On certain Mack CHU model chassis, there may be leakage at the lower radiator hose connection, or disengagement of the hose from the lower radiator tube. Effective September 5, 2007, a longer lower radiator hose was implemented into production. The longer hose provides a more secure connection to prevent leakage or hose displacement.
The new Part No. for lower radiator hose made of EPDM material is 11MF4595M. It replaces Part Nos. 11MF4545M and 11MF4546M. Part No. 11MF4596M is made of silicone material and replaces Part Nos. 11MF454fM and 11MF4548M.
If you discover leakage at the lower radiator hose or disengagement of the hose from the lower radiator tube in CHU models manufactured prior to September 5, 2007, use either of the new hoses depending on the original equipment.
When installing the replacement hose, slide the hose into the lower radiator tube until the end of the hose is against the dimple of the tube. Additionally, to ensure proper hose alignment, align the mark on the hose with the alignment arrow on the tube (see figure 7).
Safety Recalls
The National Highway Traffic Safety Administration (NHTSA) has issued the following recalls:
- The positive battery cables that supply power from the batteries to the starter may be routed near the engine’s exhaust manifold on certain 2007 and 2008 International MXT models. The excess heat generated by the manifold can cause the cable’s insulation to melt, exposing bare wire. This may cause an electrical short or a fire. Battery cables should be inspected, replaced as needed and rerouted away from the engine exhaust manifold.
- On certain 2006 Kenworth T800 emergency vehicles equipped with Cummins CM850 diesel engines, the connecting rods are defective and can result in seizure of the piston pin. A piston pin seizure can result in a mission-disabling engine failure. The defective connecting rods need to be replaced.
- Certain 2005 to 2007 Kidron van trailers fail to comply with the requirements of Federal Motor Vehicle Safety Standard No. 233, “Rear Impact Guards.” During testing, the slider suspension rail between the rear impact system and the rear support at the rear of the rig system are deformed. The rig system is comprised of the rear impact guard and the trailer support system. The testing procedure was for guard energy absorption and guard strength. The purpose of the standard is to reduce the number of deaths and serious injuries that occur when light-duty vehicles collide with the rear end of trailers and semi-trailers. For vehicles that fail to meet the standard, supports need to be installed between the trailer crossmembers above the end of the slider rails.
- On certain 2006 to 2008 Mack CHN, CL, CT, CTP, CV, CXN, CXP and CXU truck models and certain 2007 to 2008 Volvo VHD, VNL, VNM and VT truck models equipped with an SAF Holland Simplex fifth wheel, the lever arm pivot bolt may have been over-tightened. An over-tightened pivot bolt can distort the pivot bolt spacer sleeve, which may prevent the fifth wheel latch jaw from closing and latching securely around the trailer king pin. The pivot bolt could become loose without the driver’s knowledge. The driver could drive away and the trailer could become disengaged. To fix the problem, replace the pivot bolt and sleeve with a hex head shoulder bolt and washer.
- The daytime running lights module on certain 2008 Mack CHU, CXU, GU, LEU and MRU truck models may contain a suspect metal-oxide semiconductor field effect transistor (MOSFET) that could overheat. An overheated transistor could result in a vehicle fire. The suspect DRL module needs to be replaced.
- The bolts that attach the steering gear to the frame on certain 2008 model year Mack CHU, CXN and CXU models and 208 Volvo VNL, VNM and VT models may not have been tightened to the specified torque. This could result in loss of steering control. To repair, tighten the bolts to the proper torque.
- On certain 2007 model year Utilimaster Aeromaster walk-in delivery vans, the headlight modules were wired incorrectly. This can cause the headlamp to operate with reduced effectiveness. Verify that the wiring is wired incorrectly and repair it.
Viscous Fan Drive Fault
On certain Mack model chassis equipped with either an MP7 (U.S. 2007 emission compliant) or MP8 engine, a driver may experience an electronically controlled viscous fan drive full-time engagement (until the ignition key is cycled off and on), and an MID 128, SID 33, FMI 4 fault code may be logged.
Generally there are no cooling system problems associated with the full-time fan engagement, nor with the fault code.
To correct this condition, a new engine dataset has been developed and was implemented into production as follows:
- Vehicles equipped with MP7 (U.S. 2007 emission compliant) engines – engine manufacture date November 19, 2007, and later beginning with Serial No. 512456.
- Vehicles equipped with MP8 engines – Engine manufacture date October 15, 2007, and later beginning with Serial No. 905617.
If you encounter full-time fan engagement and a logged MID 218, SID 33, FMI 4 fault code on a vehicle having an engine manufactured prior to the above dates, reprogram the EECU with the current software.
