Steps 2 Through 5

STEP 2 LINE PRESSURE TESTS:




Road test and compare all pressures to chart. Use a hand vacuum pump to regulate vacuum during 10" and WOT tests. (Figure 1)

MODULATOR TESTS:

1. Vacuum to modulator at idle warm, should be at least 16" at sea level.

2. Vacuum must drop below 2" on a quick WOT.

If either of these specifications cannot be met, check for bad vacuum hoses, plugged ports, worn timing chains, or restricted intake or exhaust.




3. Check modulator pin length, free valve movement (Figure 2) and be sure you do not have a C3 modulator installed.

A4LD MODULATOR PIN LENGTH = 1.375" Average

A4LD MODULATOR APPLICATION

E5TZ-7A377-B Altitude Comp. 85-89 Ford Mercury
E5TZ-7A377-C Standard 87 - on Mustang, Bronco, Ranger
E4SZ-7A377-A Turbo Charged 87-89 T-Bird
E4SZ-7A377-B Altitude Comp. 87-89 T-Bird
F0TZ-7A377-A Altitude Comp. - 4.0 CI 90 - on Aero/Bronco/Ranger

SERVO PRESSURE TEST:

Drill and tap the overdrive servo. Line pressure should be present any time the engine is running. If not, check for a valve body gasket that's covering the servo feed hole.

STEP 3 GOVERNOR TESTS:

Note
line pressure must be checked first.




Remove the extension housing, governor body and pan Blow air into the governor return passage. Figure 3. Check for leaks around the valve body, valve plugs, governor ring area etc. At the same time, check for a stuck 3-4 shift valve.

As you apply and release air into the governor return passage, you should be able to feel the 3-4 shift valve tapping on the plug. If not your valve body may be too tight. Loosen and retighten the valve body bolts to 70 in. lbs and try it again. (This should be a rebuild procedure).

Note
There is an untapped boss (Figure 2) for governor pressure cast into the right side of the case. It may be to your advantage to drill and tap this during rebuild for future use.


STEP 4 CHECKBALL AND SEPARATOR PLATE I.D.:







Make sure your checkballs and separator plate are correct for the model you're working on. See figures 4 and 5 for this.

Valve Body, Separator Plate and Check Ball Locations


STEP 5 CASE AND VALVE BODY PREPARATION:

1. Cross-file case and valve body with a large single cut file

2. Block plane both surfaces with 240 or 320 emery cloth

3. Install 2 case to separator plate gaskets

4. Torque valve body starting from center out, in two steps, with the final torque at 70 in. lbs.