Temperature Sensors
On Mack vehicles equipped with an ASET AC engine, temperature sensor Part No. 64MT450A is used to measure intake air, charge air and turbocharger compressor discharge air temperatures. To address premature failure of the intake air and charge air cooler temperature sensors, Mack has issued a revised sensor (Part. No. 64MT485).
This revised sensor includes a higher temperature O-ring and a teflon shield, and should be used as the service replacement for a failed intake air or charge air cooler temperature sensor.
Failure of a turbocharger compressor discharge temperature sensor, however, usually is the result of air turbulence created by cooling fan engagement which causes the protective sleeve on the pigtail harness to rub against wire insulation.
Eventually, the insulation rubs through and exposes the bare wire, resulting in breakage of the individual wire strands. Once this occurs, the sensor will fail. A failed turbocharger compressor discharge temperature sensor must be replaced with the same part number sensor (Part No. 64MT450A).
To avoid a repeat failure, the sensor pigtail harness must be secured to prevent the harness from vibrating and flexing as a result of air blasts from the fan.
Note: Do not use the 64MT485 sensor to replace a failed turbocharger compressor discharge temperature sensor. This sensor must be replaced with the same sensor (Part No. 64MT450A).
On CH and CHN models, the pigtail harness is unsecured, and the sensor harness connector is clamped to the inlet air duct clamp, as shown in Figure 1.
On these models, remove and discard the connector clamp, and then use tie wraps (Part No. 48RU2313P2) to secure the pigtail harness to the air conditioner line, as shown in Figure 2.
On CX and CXN models, secure the pigtail harness, as shown in Figure 3.
Interference With Refrigerant Line
On Mack MRU model chassis manufactured prior to July 23, 2007 and equipped with front engine power take-off (FEPTO), there is an interference condition between the air conditioning refrigerant line and the FEPTO driveshaft.
To eliminate this condition, Mack has made a revised refrigerant line (Part No. 212RD4111M) available. The revised refrigerant line is routed above the FEPTO opening in the radiator, thus eliminating any interference with the driveshaft (see Figure 4).
Revised Power Steering Oil Cooler Hose
Effective January 31, 2008 Mack implemented a revised power steering oil cooler hose (Part No. 21047263) into production. This replaces the original hose (Part No. 21047242) on GU model chassis equipped with an MP7 engine.
This change was made to correct an interference condition that exists between the power steering oil cooler hose and the lower frame flange (see Figure 5). If you discover contact between the power steering oil cooler hose and the frame rail lower flange on a chassis manufactured prior to January 31, 2008, replace the existing hose with the revised hose.
Installing Front Gears & Dampers
There may be an issue of clearance with the front gear housing on Caterpillar 3408B (S/N: 28V1-Up) engines, if the gear group is reused on a remanufactured engine.
Use the following procedure to ensure that there is enough clearance between the front housing and the gear (see Figure 6):
- Remove the engine and the torque converter from the application.
- Remove the existing damper, front housing, camshaft drive gear and cluster idler gear from the engine.
- Clean the engine and inspect it in order to make sure that it does not contain any damaged parts or debris from damaged parts.
- Conversion to the new wider cam gear and idler gear assembly requires some modifications to the front gear housing. The inside surface of the front housing must be machined. Remove 3.5mm (0.1378 inch) of material from the inside surface of the front housing.
- Modify the front support bracket for the engine to the dimensions shown in Figure 7. This will make sure the damper will have enough clearance. Do not flame cut the front engine support. The front engine support must be machined. Note: The 105-9084 Engine Support GP requires some modifications. The 7E-6385 Engine Support GP does not.
- Install the new 195-0318 camshaft gear onto the camshaft. The preferred method of installing the cam gear is by pressing it onto the camshaft without the use of heat.
- Install the new 195-0316 gear assembly.
- Install the camshaft assembly into the engine.
- Install the front housing, modified engine support, 167-8130 damper, 6N-6037 damper adapter, 6N-7654 spacer and the required pulley assembly.
Safety Recalls
The National Highway Traffic Safety Administration (NHTSA) has issued the following recalls:
- The Fabco slack adjuster on SISU axles on certain 2005 to 2007 model year Kenworth C500, T800, W900, and Peterbilt 357 and 379 tractors may fail as a result of a fatigue crack rendering the slack adjuster inoperative. Reduction in braking capacity could increase the risk of a crash. Inspect the slack adjusters and replace them if you find this problem.
- More than 300 2007 to 2009 model year Kenworth T800, W900 and Peterbilt Models 357, 365, 367, 378, 379, 384, 385, 386 and 389 trucks equipped with Premier trailer hitch assemblies may have pivot pins that were manufactured out of specification. This results in a reduction in fatigue strength of the pivot pins. This could cause the pivot pin to crack and eventually break causing the trailer to detach from the truck while in motion. Defective pivot pins need to be replaced.
- More than 700 2007 to 2008 model year Dodge and Freightliner Sprinter 2500 passenger vans equipped with a 144-inch wheelbase and standard roof height fail to comply with the requirements of Federal Motor Vehicle Safety Standard No. 201U, Occupant Protection In Interior Impact. Some vans may not have had certain head impact protection pads installed at the C-pillar. In the event of a vehicle crash, personal injury to occupants may occur. If the pads are missing, the appropriate pads will be installed.
- Forty Dodge and Freightliner Sprinter 3500 cargo vans, model years 2007 to 2008, fail to comply with the requirements of Federal Motor Vehicle Safety Standard No. 105, Hydraulic And Electric Brake Systems. Some of these vans may not have had the correct brake components installed. This standard specified requirements for vehicles equipped with hydraulic and electric service brake systems and associated parking brake systems. The purpose of the standard is to ensure safe braking performance under normal and emergency conditions. Installing the appropriate master brake cylinder and brake fluid reservoir will fix the problem.
- There may be a fractured fuel line which could leak fuel on 62,000 model year 2005 to 2007 Freightliner Business Class, Century Class, Columbia, Coronado, FLD, Classic trucks; Sterling A-Line, L-Line trucks; and Western Star 4900 trucks. If a leak continues undetected under certain conditions, fuel may ignite at a hot engine surface or fuel may be spilled on the road surface.
