Issue Summary:
- Fluid foaming in the 41TE may be caused by the cooler bypass valve in the case under the pump.
- Delayed bang engagement on the Honda Civic HX may be caused by several reasons, one of which is a stretched steel belt slipping in the pulleys.
- After replacement of a turbine-speed sensor, Ford/Mazda CD4Es may experience a persistent gear-ratio error.
- We also have included a special conversion procedure for Mazda-to-Ford ID.
As soon as the vehicle is started, the fluid becomes foamy and rises high on the dipstick.
Some valve bodies had a casting problem around the area of the filter O-ring that would allow air to get past the O-ring, producing the pump-cavitation complaint. However, this cause has diminished considerably, since many of these valve bodies have been removed from circulation. It still is a good idea to drop the pan first and check the filter and filter O-ring for proper operation.
A more-common possibility occurs in units equipped with cooler bypass valves in the case under the pump (see Figure 1).
An exploded view of this valve in Figure 2 reveals that it is a spring-loaded checkball within a capsule.
If the ball remains off its seat (see Figure 3) at all times, the “to-cooler” fluid dumps immediately back into the sump, foaming the fluid. Since this assembly is encapsulated, this condition of the ball stuck off its seat can be overlooked easily.
Repair or replace the cooler-bypass-valve assembly.
- Cooler Bypass Valve Part Number: 4659946
1996-98 Honda Civic HX equipped with the continuously variable transmission (CVT) may experience a delayed harsh engagement in both drive and reverse.
Some of the common causes that produce this complaint are:
- A mechanically failed start-clutch solenoid (Figure 4).
- Sticking start-clutch control valve (Figure 4).
- A leak in the start-clutch drum circuit
- A cracked drive pulley (Figure 5).
- A stretched steel belt slipping in the pulleys (Figure 5).
Check the start-clutch pressure circuit with a pressure gauge. Figure 6 provides the tap location. Honda does not publish pressure specifications for this tap, but checking good operational vehicles has found 35-40 psi of pressure at idle in Drive. At stall in Drive, this pressure reached 120-130 psi. This will verify the integrity of the start-clutch solenoid, valve and drum. If this pressure is low, one of these items is faulty. If pressures are within specifications, there may be problems with a pulley or steel belt.
Pulleys are known to crack, causing a loss of squeeze pressure on the belts. Figure 7 illustrates the remaining pressure-tap locations, and Figure 8 shows pressure specifications. Pressure-check both the drive and driven pulleys. If one or both are low, an internal inspection is necessary. Many times the cracks in the pulleys are visible. If the pressures are within specification, chances are the steel belt has stretched and will need to be replaced.
Caution:
Pressure on the pulleys can reach 600 psi or greater. Be sure to use an appropriate gauge.
After replacement of the turbine-speed sensor (TSS), TCC-slip code 628 and/or P1744 may be stored. One of more of the gear-ratio-error codes 628, 642, 645, 646, 647, 648, P0731, P0732, P0733, P0734, P0741 and P1744 also may be stored. After you clear these codes, they return immediately during the road test.
No matter which parts are replaced or which procedure is followed, these codes keep returning.
The cause, believe it or not, is the replacement turbine-speed sensor. The redesigned sensor has an enclosed pickup (see Figure 9). The all-black TSS has an exposed pickup, also shown in Figure 9.
It seems that when the pickup was enclosed, the air gap between the TSS and the reverse-clutch hub increased. When the signal is checked and compared with that of the all-black sensor, the new sensor’s signal exhibits a voltage difference. However, when checked with an oscilloscope, the all-black sensor puts out a wider pattern than the new-design sensors, which means the computer has more time to read the signal with the all-black sensor.
In other words, with the current-design turbine sensors, the computer does not have enough time to read the signal and may miss alternate signal pulses, resulting in the complaint mentioned.
If any of these codes is stored after replacement of the turbine-speed sensor, consult the chart in Figure 10 to ensure that the correct sensor is installed for the application, since all TSS designs are now available.
From 1991 to 1994, certain Mazda vehicles use EEC-IV diagnostics that are supported in the Snap-on Domestic Primary and Domestic Troubleshooter cartridges. You must use the Domestic Primary and Troubleshooter rather than the Asian Primary and Asian Troubleshooter cartridges.
Snap-on Domestic Primary V 6.7 or later uses identification by four VIN characters. For example, instead of using the 10th, 4th & 8th VIN characters (R-G-C) for a 1994 Mazda 626 2.0-liter, use the 10th, 2nd, 5th & 8th characters (R-Z-T-A), which in this case would correspond to the ID of a 1994 Probe 2.0-liter.
Also, 1995-2001 Mazda B-Series trucks may be identified (in Domestic Primary) as Ford Ranger trucks, thereby making more live data available.
July 2002 Issue
Volume 19, No. 7
- 41TE: Fluid Foaming
- Honda Civic HX: Delayed Bang Engagement
- Ford/Mazda CD4E: Persistent Codes for Gear-Ratio Error or TCC Slip
- Special Conversion Procedure for Mazda-to-Ford ID