Issue Summary:
- Harsh reverse engagement in Volvo AW50-42LE can have four possible causes.
- Chrysler RWD units may experience repeated failures from meltdown of the front quick-disconnect line clips. Replace the quick-disconnect fittings with threaded fittings that will not melt.
- Revisions have been made to the valve body and spacer plate on Ford AODE/4R70W.
- Transmission-fluid leak from the vent in a 4T65-E can be prevented by replacing the upper-channel-plate cover gasket with an updated gasket.
- A stator support turned inside the cover of a ZF-5HP-18 in a BMW can cause no power on take-off, neutralizing, bind-ups and failsafe.
- Check for a defective mass-air-flow sensor in AX4S/N, AODE/4R70W and E4OD with converter-clutch shuttle.
Harsh engagement into reverse; forward engagement is normal. Line pressure is also normal.
There can be four possible causes:
(1) Misadjustment of the manual valve due to a linkage problem or the manual valve link that connects the internal linkage to the manual valve (see Figure 1).
(2) The installation of flat friction plates instead of the OE-style waved friction plates in the C2 (direct) clutch pack (see Figure 2).
(3) Wearing of the center ring land in the C1 (forward)/C2 (direct) drum in the rear cover (see Figure 3).
- Caution:
- Early units use an aluminum support in the rear cover, which must use metal rings. Late units use a steel support, which uses Teflon® rings. The use of Teflon rings in an early cover with the aluminum support will destroy the support.
(4) A worn upper torque arm, which cushions engine movement when reverse is selected (see Figure 4).
Make the corrections as follows:
(1) With the shift lever in the Park position, the end of the manual valve should be flush with the valve-body casting as shown in Figure 1, and replace worn parts as necessary.
(2) Make certain when replacing the C2 (direct) friction plates that they are waved (see Figure 2).
(3) Be sure to check the center ring land for wear (see Figure 3) and to replace the rear cover if the ring-land wear is excessive, preferably using a rear cover with the steel support.
Also be sure to use the correct rings for the type of material the support is made with as follows:
- Aluminum Support………………………. Metal Rings
- Steel Support…………………………….. Teflon Rings
(4) Check the condition of the upper torque arm (see Figure 4) and replace as needed.
Chrysler rear-wheel-drive transmissions with quick-disconnect 1⁄2-in. cooling lines may experience repeated failures from meltdown of the front line clips (See Figure 5).
This complaint is most common in RWD transmissions behind diesel engines after heavy trailer towing or reverse-to-drive rocking situations. This causes the front cooling line (which is the line out to the cooler) to experience the high fluid temperatures produced by the converter. The front quick-disconnect clip assembly suffers greatly under these conditions.
Replace the transmission quick-disconnect fittings with threaded fittings that will not melt. This will require two cooling lines with the appropriate attaching fittings, two case fittings to accommodate the case threads and line fittings, plus about two feet of flexible hydraulic lines to attach the new lines to the existing lines.
Fittings:
- (2 Case Fittings) …………..52028764AA
Cooling Lines:
- (1 Front Line*)………………..5011244AA
- (1 Rear Line)…………………….52028673
*This front-cooling-line part number includes the one-way checkvalve and temperature-sensor port.
Clarity needed toward valve-body-gasket application.
Revisions have been made to the valve body and spacer plate because of calibration and control concerns that necessitated changes to the gaskets.
The previous spacer-plate-to-case gasket was part number F7AZ-7C155-AA and had a green stripe. The revised gasket is part number 1L3Z-7C155-AA, and it too has a green identification stripe. This gasket will retrofit all applications and model years from 1996 to present.
The spacer-plate-to-valve-body gasket with part number XW7Z-7D100-AA has a white identification stripe and is used for 1996 to 2000 models (see Figure 1). The spacer-plate-to-valve-body gasket with part number 1W7Z-7D100-AB has a light-blue identification stripe and is used for all 2001-and-up applications. This gasket will NOT retrofit to any previous model years (see Figure 6).
Vehicles with the Hydra-matic 4T65-E transaxle having RPO codes MN#, MN&, M15 and M76 may experience chronic transmission-fluid leaks coming from the breather (vent) atop the transaxle before and/or after rebuild.
The line pressure, which passes through the upper-channel-plate gasket to reach the pressure tap, is blowing past the gasket into the vent circuit and exiting the vent.
Replace the upper-channel-plate cover gasket with an updated gasket issued by General Motors. The most susceptible area of the gasket that the line pressure was able to blow across has been closed off, allowing for greater retention and eliminating the leak (see Figure 7).
- New Upper-Channel-Plate Cover Gasket…………………….24206391
BMW’s M3, 530i and 320i vehicles equipped with the ZF-5HP-18 transmission may exhibit a condition of no power on takeoff, feeling as if the stator in the converter is defective. Other complaints may be sudden neutralizing, bind-ups and failsafe.
It is not uncommon to find that the stator support in the pump cover has turned. The severity of the turn will determine the type of complaint.
If the stator support has turned inside the cover, the assembly will need to be replaced. The replacement support and cover is called by ZF Industries “The Intermediate Plate” (see Figure 8). The part is 1056-210-119 and lists for $524.45.
Gasoline-powered vehicles with AX4S/N, AODE/4R70W or E4OD transmissions may experience converter-clutch shuttle without exhibiting any codes. This complaint may be accompanied by late shifts and/or rough-running engine.
The mass-air-flow (MAF) sensor may be defective, producing erroneous engine-load data to the PCM and altering converter-clutch and shift strategy. The MAF sensor is between the air cleaner and the throttle body (see Figure 9). The MAF sensor uses a heated wire as a sensing element to measure the amount of air that is entering the engine. The air that passes over the heated wire causes the wire to cool. The MAF sensor then sends a DC analog voltage signal to the PCM, which uses that signal to determine the amount of air that is entering the engine. The PCM will calculate the fuel-injector pulse width in order to provide the proper air/fuel ratio.
The MAF-sensor signals are also used for electronically controlled transmissions and transaxles in determining EPC pressure control, shift and TCC strategies. For the purpose of transmission and transaxle diagnosis, symptoms of MAF-sensor malfunction or failure could include high or low EPC pressure, improper shift scheduling or incorrect TCC scheduling.
Testing the MAF will require the use of a digital volt/ohmmeter set to DC volts. Connect the leads to the sensor harness wires at terminals C and D (see Figure 10). With the engine running at idle, the voltage should read 0.60-1.2 volts. This idle-reading voltage will vary with engine and ambient temperature.
Refer to the chart in Figure 11 for the approximate sensor data, and replace the sensor if needed.
Note:
If it has been determined that the MAF sensor needs to be replaced because of erratic or erroneous readings, it is possible to carefully disassemble the MAF sensor to view the heated wire. There may be a piece of foreign material burned onto the wire. If this is discovered, use a can of compressed air for cleaning computer keypads to carefully try to clean all debris from the wire. The wire is very brittle and can break easily. If cleaning the wire was successful, you may have resolved your MAF-sensor problem without having to buy a new one.
May 2002 Issue
Volume 19, No. 5
- Volvo AW50-42LE: Harsh Reverse Engagement
- Chrysler RWD Units: Meltdown of Front Cooler-Line Clips
- Ford AODE/4R70W: 1996-and-Up Valve-Body Gaskets
- Hydra-matic 4T65-E: Transmission-Fluid Leak From Vent
- ZF-5HP-18 Transmission: No Power on Take-Off, Neutralizing, Bind-Ups and Failsafe
- AX4S/N, AODE/4R70W, E4OD: Converter-Clutch Shuttle