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 MANUALSCHEVROLET1990LUMINA APV V6-191 3.1LREPAIR AND DIAGNOSISTRANSMISSION AND DRIVETRAINAUTOMATIC TRANSMISSION/TRANSAXLESERVICE AND REPAIROVERHAULINTERMEDIATE SERVO
1990 Chevrolet Lumina APV V6-191 3.1L
Intermediate Servo
1990 Chevrolet Lumina APV V6-191 3.1LSECTION Intermediate Servo
Disassembly & Inspection

1. Remove E-ring from apply pin, then separate intermediate servo piston, cushion, spring, spring retainer and apply ring, Fig. 79.
2. Inspect orifice cup plug in intermediate bore.
3. Inspect apply pin for damage and free fit in bore.
4. Inspect apply pin seal ring and both piston seal rings for damage and free fit in their grooves. Do not remove seal rings unless replacing.
5. Inspect cushion spring and retainer for damage.
6. Inspect servo cover and piston assembly for porosity or damage.
7. Check for proper intermediate band apply pin as described under "DISASSEMBLY, External Components".
Assembly & Installation
1. Install spring retainer onto small diameter end of apply pin, then install spring on retainer.
2. Install piston with larger diameter end first, then compress spring and install E-ring.

3. If removed, install new seal rings. Make sure cut ends are installed in same relationship as cut, Fig. 59. Make sure rings are properly seated in their grooves.
4. If removed, install intermediate bands apply pin seal ring. Make sure seal ring is seated in its groove.


5. Install 3rd accumulator check valve, Fig. 5, then install intermediate servo piston assembly, Fig. 3. If transaxle had a 3rd accumulator cup plug, and it was removed, do not reinstall. Replace servo cover and gasket with replacement type which takes place of cup plug.
6. Install intermediate servo cover gasket, servo cover, three cover retaining screws and the oil pipe retainer bracket and screw. Refer to "Torque Specifications Chart" for torque values.
Fig. 79, Intermediate servo exploded view:
1. Remove E-ring from apply pin, then separate intermediate servo piston, cushion, spring, spring retainer and apply ring, Fig. 79.
2. Inspect orifice cup plug in intermediate bore.
3. Inspect apply pin for damage and free fit in bore.
4. Inspect apply pin seal ring and both piston seal rings for damage and free fit in their grooves. Do not remove seal rings unless replacing.
5. Inspect cushion spring and retainer for damage.
6. Inspect servo cover and piston assembly for porosity or damage.
7. Check for proper intermediate band apply pin as described under "DISASSEMBLY, External Components".
Assembly & Installation
1. Install spring retainer onto small diameter end of apply pin, then install spring on retainer.
2. Install piston with larger diameter end first, then compress spring and install E-ring.
Fig. 59, Oil seal ring installation:
3. If removed, install new seal rings. Make sure cut ends are installed in same relationship as cut, Fig. 59. Make sure rings are properly seated in their grooves.
4. If removed, install intermediate bands apply pin seal ring. Make sure seal ring is seated in its groove.
Fig. 5, Removing 3rd accumulator check valve & spring:
Fig. 3, Exploded view of intermediate servo assembly:
5. Install 3rd accumulator check valve, Fig. 5, then install intermediate servo piston assembly, Fig. 3. If transaxle had a 3rd accumulator cup plug, and it was removed, do not reinstall. Replace servo cover and gasket with replacement type which takes place of cup plug.
6. Install intermediate servo cover gasket, servo cover, three cover retaining screws and the oil pipe retainer bracket and screw. Refer to "Torque Specifications Chart" for torque values.
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:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.