Tech Updates – July 2008

Windshield Wiper Arm
Beginning August 2003 through July 2007, windshield wiper arms with non-replaceable windshield washer nozzles were used in production on all Mack conventional model chassis (CXU, CHU, GU, CXP, CXN, CX, CTP, CT, CHN, CH, CV and CL). Effective August 2007, a windshield wiper arm having a replaceable windshield washer nozzle was implemented into production.

Replacement nozzles (Part No. 8609-80014221) are available if you need to replace the existing nozzles. The replacement nozzle consists of a holder and two pre-aimed nozzles.

If you need to replace a windshield washer nozzle, first determine which wiper arm is being serviced. Wiper arm Part No. 62QT514(A) uses non-replaceable washer nozzles, as in Figure 1. If this is the case, the wiper arm must be upgraded to wiper arm Part No. 82150073 which uses the replaceable washer nozzles. With this wiper arm, the nozzles can then be serviced at a later time if required.

To replace the washer nozzle, use the following procedure shown in Figure 2.

1. Remove the wiper from the wiper arm assembly.
2. Disconnect the hose from the washer nozzle holder.
3. Rotate the nozzle holder assembly counterclockwise until the locking tabs are released from the locking pin.
4. Slide the washer nozzle holder off the wiper blade shaft.
5. Install the replacement nozzle assembly (Part No. 8609-800014221) using the reverse of the procedures used for removal.

Air Reservoir Drain Procedure
To help keep the vehicle’s air dryer functioning at maximum efficiency, Meritor WABCO recommends that you advise customers to check the vehicle’s air system reservoirs for water accumulation on a daily basis, such as at the end of each driving shift.

Instruct customers to use the following procedure when checking the air system reservoirs:

• Prior to checking the reservoirs, remove all pressure from the air system before disconnecting any components.
• Begin with the supply reservoir. With the air system under normal operating pressure, momentarily open the drain valve and watch for evidence of moisture, such as a spray or droplets.
• If no moisture is detected, the valve can be closed. If moisture is detected, repeatedly open the drain valve for short periods of time, several seconds at most, until the moisture is no longer visibly ejected from the reservoir. Wait several seconds between each opening to allow moisture to flow back to the drain valve area inside the reservoir. Once nothing is detected, close the drain valve and go to the next reservoir.
• If during the process of trying to eliminate all moisture from the reservoir, the air pressure drops to zero, leave the valve open for several seconds, then close it.
• Repeat this process with all remaining reservoirs.

This procedure is intended to remove all liquid from the reservoir without completely draining the air. The less the air compressor and air dryer have to work to refill the system, the more efficient the air dryer will function. Completely refilling the whole air system volume every day puts an unnecessary moisture load on the air dryer, which will require additional purge and regeneration cycles in order to reach a stabilized dryness condition.

If customers find excessive moisture in the air system on a daily basis, one or all of the following procedures may be necessary:

• Check the system for air leaks.
• Replace the vehicle’s air dryer desiccant cartridge.
• Evaluate the vehicle’s application to determine that the correct components have been used.

Air Dryer Caution
In addition to the cautions listed in Bendix’s AD-3 Service Manual and Installation Instruction Sheets, technicians should adhere to the following procedures before servicing the AD-2 air dryer:

1. Drain all reservoirs completely.
2. Loosen the air line to the control port of the air dryer and allow the trapped air to escape into the atmosphere. After the air escapes, remove the control line from the air dryer.
3. Loosen the delivery line from the delivery port or outlet of the air dryer. After the pressure drops, remove the delivery line. Loosen the delivery check valve from this port to relieve any trapped air above the desiccant plate assembly, as shown in Figure 3.
4. Remove any exhaust silencers or the exhaust check valve cover from the base of the air dryer. Using a hex socket and wrench, loosen the purge valve assembly and allow any trapped air to escape. Slowly unscrew the purge valve and remove it.
5. Check all ports to ensure that air is not trapped in the air dryer by powdered desiccant material.

The AD-2 air dryer cartridge contains a high spring load. When replacing the cartridge or performing maintenance requiring end cover removal, follow the procedure outlined below:

1. Loosen the three cap screws on the end cover and turn the retaining clamps aside (cap screws may be left finger tight).
2. Locate the notch in the air dryer shell. While pushing the end cover up into the dryer, insert the blade of a screwdriver in the notch and slowly pry out the retaining ring. If the cartridge bolt has loosened, the cartridge spring may exert a force on the end cover retaining ring making removal of the retaining ring and end cover difficult. This spring force will prohibit the end cover moving up into the dryer shell when pushed up.
3. This same force also can cause the end cover to come out of the air dryer shell unexpectedly during the removal process. Therefore, do not stand or lay directly under the end cover while servicing. Assure adequate clearance between the end cover and other surfaces to prevent hand injury if the end cover dislodges rapidly during removal.
4. Proceed with normal maintenance procedures.

Safety Recalls
The National Highway Traffic Safety Administration (NHTSA) has issued the following recalls:

• The two vertical right/left side front spring bracket bolts on 16,805 model year 2005 to 2008 Hino NA6J, NB6J, NC6J, ND6J, NE6J, NJ8J and NV8J trucks were not tightened properly during the assembly process. This may cause increased stress on the spring bracket which can lead to cracking of the bracket. This could reduce steering control, increasing the risk of a crash. The vertical front spring bracket attachment bolts on the right/left hanger brackets need to be replaced and all associated bolts need to be retorqued.
• TRW steering gear, Model TAS85, manufactured between August 13 and September 13, 2007, and installed as original equipment on commercial vehicles, contain potentially defective sector shafts with an incorrect gear tooth. This may interfere with the rack-piston teeth, resulting in a stick or bind condition. This condition has the potential to cause the steering gear to stall and restrict the steering turning radius angle of the vehicle, which could result in a vehicle crash.
• The rear engine support bracket on 10,325 model year 1999 to 2004 Mitsubishi Fuso FE639 and FE649 trucks is composed of material of insufficient strength. Normal vehicle vibrations may cause the bracket to crack. If the vehicle is continually operated in this condition, the bracket may break apart. The transmission could drop out of alignment with the drivetrain. A modified rear engine support bracket needs to be installed to correct the problem.
• There is an issue with approximately 15,500 model year 1999 to 2004 Mitsubishi Fuso FE639, FE649 and FG639, model year 2001 to 2004 FE640 and model year 2003 to 2004 FH210 trucks equipped with automatic transmissions. Normal heat emanation from the exhaust pipe may cause the automatic transmission shift linkage to deform. The effort required to operate the automatic transmission shift control lever may increase if the linkage binds as a result of deformation. The shift control lever may become inoperative or the physical shift lever position on the shift lever housing gear indicator may not match the actual gear selection at the transmission. A modified automatic transmission shift control lever assembly needs to be installed.