Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSFORD1991TAURUS L, 4D SEDAN, 3.8 4REPAIR AND DIAGNOSIS (SINGLE PAGE)TRANSMISSIONAUTOMATIC TRANSOVERHAUL - AXOD-ETRANSAXLE REASSEMBLYOVERHAUL - AXOD-ESERVO PISTON TRAVEL CHECK - OVERDRIVE SERVO
1991 Ford Taurus L, 4D Sedan, 3.8 4
Servo Piston Travel Check - Overdrive Servo
1991 Ford Taurus L, 4D Sedan, 3.8 4SECTION Servo Piston Travel Check - Overdrive Servo
- Install spring from Overdrive Servo Rod Kit (T86P-70023-B) in case. Install servo piston and rod in case. Install servo piston gauge from kit and secure in case using servo cover bolts. Tighten bolts to 90 INCH lbs. (10 N.m). Tighten gauge center screw to 10 INCH lbs (1.13 N.m). See Figure .
- Attach a dial indicator and position stylus through hole in gauge. Ensure stylus contacts piston on a flat surface. DO NOT contact step on piston. Zero dial indicator.
- Back off gauge center screw until piston movement stops and read piston travel on dial indicator. Piston travel is determined by servo rod length. Piston travel should be .070-.149" (1.8-3.8 mm).
- If piston travel is not within specification, change piston rod and recheck. Piston rod is identified by number of grooves located on tip of rod. See OVERDRIVE SERVO ROD SELECTION . Install overdrive servo assembly. Install new seals, cover and bolts. Tighten bolts to 84-108 INCH lbs. (10-12 N.m).
OVERDRIVE SERVO ROD SELECTION
| Number Of Grooves In Rod Tip | Rod Length: Inch (mm) |
|---|---|
| 0 (No Grooves) | 3.911 (99.33) |
| 1 | 3.860 (98.05) |
| 2 | 3.810 (96.78) |
RENDER: 1.0x
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.