Figure 1a |
Figure 1b |
Figure 2 |
E4OD Pump Updates and Interchange
by Michael Baird
From 1989 1998 we've seen a multitude of changes in the E4OD pump design. Then in 1998, Ford introduced the 4R100, which had other variations of the E4OD style pump, not all of which are interchangeable with the earlier units. In this article we'll go over interchange, design changes, and compatibility between the pumps for these two units.
In 1989 the E4OD pump was introduced with a rough forge casting number RF-E9 (figure 1a and b). Soon after, in 1991, the stator support was redesigned; it had a rough forge number of RF-F1 (figure 2). The pump body, however, remained the same.
The changes that took place in 1991 were in the converter charge pressure exhaust orifice, which increased by 0.020", and the converter apply pressure lube orifice, which increased by 0.010" (figure 3). Another change was in the area of the stator support shaft used for converter apply and discharge pressure. The passage was machined into the shaft rather than cast into the support body (figures 4a,b and c).
The next changes took place in 1995. Again the rough forge number changed, this time to RF-F5 (figure 5a and b). The stator support had a minor casting change to the suction area, to direct fluid toward the rotors (figure 6). The pump body was also cast in this manner to increase flow to the improved design rotors (figure 7). The rotor's outside diameter was increased from 3.950" to 4.083". In addition, the rotor lobes were decreased by one on each rotor (figure 8). This increased the volume of fluid to help with delayed reverse engagement problems, especially when hot; and, like the 1991 changes, reduced converter slip problems.
Up until 1998 all of the pumps could be interchanged, either as a complete set or as separate components. Along with the 4R100 came three new pump designs; only one will retrofit to 1989 1998 E4ODs, and only as a complete assembly. While they all have rough forge casting numbers RF-F8 (figure 9a and b), there are a few noticeable changes:
1. Bushing or bearing contact surface area varies on the stator support shaft; depending on whether the coast clutch drum is cast or stamped (figure 10).
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Figure 10
2. Torque converter clutch valve is either a standard on/off or pulse width modulated (figure 11).
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Figure 11
3. The stator support shaft may have a bushing or a bearing to support the input shaft.
4. There were some casting changes that are most noticeable around the torque converter clutch valve (figure 12a and b).
 Figure 12a |
 Figure 12b |
The 1998 5.4L and 6.4L gas without power take off used a non-modulated lockup system like the E4OD. The way to identify non-pulse width modulated is:
1. The orifices are in relatively the same position as earlier designs and are still the same size (figure 13).
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for enlarged view
Figure 13
2. The torque converter clutch valve train still uses a standard plug with a threaded hole to remove it (figure 14).
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Figure 14
3. The stator support shaft can still accept the cast-iron coast clutch drum (figure 15).
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Figure 15
It's just as easy to identify a pulse width modulated stator support:
1. The torque converter clutch valve train has a bushing with a valve inside of it (figure 16).
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for enlarged view
Figure 16
2. There's a 0.116" hole drilled in the cavity for the bushing (figure 17).
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Figure 17
3. The converter charge pressure exhaust orifice was eliminated; however, the area where the orifice would be installed still has stake marks, so don't be deceived (figure 18).
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for enlarged view
Figure 18
4. An air bleed capsule was installed in the shift solenoid three circuit at the end of the converter clutch control valve (figure 17).
5. An additional 0.049" orifice was installed in the shift solenoid three circuit (figure 19).
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for enlarged view
Figure 19
6. The stator support shaft was redesigned to accept the stamped steel coast clutch drum (figure 20).
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for enlarged view
Figure 20
There is one other pump that should be mentioned, though it had limited application. This pump was only used in 1998 and 1999, for the 6.8L gasoline engine with a power take off. The pump body and stator support are the same as an on/off lockup system, but the stator support shaft is designed to accept a stamped steel drum with a power take off gear (figure 20).
In 1998, only 4R100s designed for use with a diesel engine used pulse width modulated converter clutch systems. In 1999, however, it was used in some gasoline applications. By the year 2000 all trucks used pulse width modulated lockup systems. Because of this, there is only one pump used for 2000 models. During 1998, units with power take off used a pump with a bearing to support the input shaft at the coast clutch end of the stator support, but that was eliminated in 1999.
To summarize, all pump bodies and stator supports with rough forge casting numbers prior to RF-F8 can be interchanged, as complete sets or components, and can be used on any 1989 through '97 unit. The changes we've discussed are to help you understand why they took place. This way, when you run into an early body or stator support, you'll know what to expect.
The RF-F8 non-modulated pump, with a stator support designed to accept a cast coast clutch drum, will retrofit all E4OD applications when used as a complete assembly. The three design pumps used for 1998 1999 4R100s have been dropped to one for all applications in 2000.
As always, knowing what you're working on is a major factor in the success of your rebuild. Some of the parts we've covered will interchange easily, others will not. Make sure you know what you've got before you run into problems.
