Transmission R&R - Automatic

Complete removal and reinstallation of the 6L80/6L90 6-speed automatic transmission from a 2014-2018 Chevrolet Silverado 1500 with 5.3L V8 engine.

Warnings

Tools required

Parts

• Transmission pan gasket × 1 — Use OEM specification
• Transmission drain plug crush washer × 1 — Use OEM specification
• Torque converter bolts (if reusing transmission) × 6 — Use OEM TTY bolts
• Transmission mount (inspect and replace if worn) × 1 — Use OEM specification
• Exhaust system gaskets (if disconnecting) × 1 — Use OEM specification

Fluids

• ACDelco Dexron VI ATF — 11.5 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Disconnect negative battery cable and secure away from terminal
3. Raise vehicle and support securely on jack stands at frame rails (minimum 24 inches clearance)
4. Remove skid plates or undertray panels if equipped
5. Mark driveshaft-to-differential flange orientation with paint pen for proper reinstallation alignment
6. Place drain pan under transmission pan and drain fluid by removing drain plug if equipped, or loosen pan bolts
7. Remove transmission dipstick tube from transmission (pull upward firmly)
8. Disconnect negative battery cable from transmission ground point if applicable

Procedure

1. 1

   Drain transmission fluid and remove pan
   If equipped with drain plug, remove drain plug and allow fluid to drain completely into drain pan. If no drain plug, carefully loosen all pan bolts gradually in criss-cross pattern, allowing one corner to drop slightly for fluid drainage. Once drained, remove all pan bolts and lower pan. Remove old gasket material from transmission case using plastic scraper. Inspect pan for metal debris or clutch material.
   Torque spec

   Drain Plug42 Nm (31 lb-ft)

   Pan Bolts20 Nm (15 lb-ft)
2. 2

   Disconnect cooler lines and electrical connections
   Disconnect transmission cooler lines at transmission using line wrench or flare nut wrench. Cap or plug open lines to prevent contamination. Disconnect transmission wiring harness connectors including: main transmission connector, output speed sensor, input speed sensor, and transmission temperature sensor. Release harness clips securing wiring to transmission case.
3. 3

   Remove transmission crossmember and mount
   Support transmission with transmission jack, positioning saddle securely under transmission pan area. Remove crossmember-to-frame bolts (typically 4 bolts). Remove transmission mount-to-crossmember nuts. Carefully lower transmission jack slightly to access upper bellhousing bolts while keeping transmission stable. Do not allow transmission to hang unsupported on input shaft.
   ⚠Ensure transmission jack is centered and transmission is secure before removing crossmember support.
   Torque spec

   Mounting Bolts76 Nm (56 lb-ft)
4. 4

   Disconnect shift linkage and remove driveshaft
   Disconnect shift cable from transmission shift lever and remove cable bracket from transmission. Remove rear driveshaft: remove 4 driveshaft-to-differential flange bolts, lower rear of driveshaft, and slide driveshaft rearward to disengage from transmission output shaft. Place rag in transmission extension housing to prevent fluid leakage. Support driveshaft and remove from vehicle.
5. 5

   Remove starter motor
   Remove starter motor mounting bolts (typically 2 bolts on passenger side of bellhousing). Disconnect starter electrical connections (main power cable and signal wire). Remove starter from bellhousing and set aside. This provides access to lower torque converter bolts.
6. 6

   Remove torque converter-to-flywheel bolts
   Remove torque converter inspection cover from bottom of bellhousing (typically 2-4 bolts). Rotate crankshaft using 22mm socket on crankshaft bolt to access each torque converter bolt through inspection opening. Have assistant hold flywheel with holding tool or large screwdriver wedged in ring gear teeth. Remove all 6 torque converter bolts. Mark torque converter orientation to flywheel if reusing. Push torque converter rearward slightly to ensure it disengages from flywheel.
   ⚠Torque converter will remain with transmission when separated. Ensure it does not fall out during removal.
   Torque spec

   Flywheel Bolts95 Nm (70 lb-ft)
7. 7

   Remove bellhousing-to-engine bolts
   Remove all bellhousing-to-engine block bolts (typically 6-8 bolts). Note location of different bolt lengths and any ground straps or brackets. Upper bolts may require extension and universal joint. Remove bolts in criss-cross pattern to avoid binding transmission on dowel pins.
8. 8

   Separate transmission from engine
   Double-check that all bolts, lines, and connectors are disconnected. Ensure transmission jack is securely supporting transmission weight. Carefully slide transmission rearward, keeping it level and aligned with engine centerline. Transmission must slide straight back approximately 2-3 inches to clear dowel pins and input shaft from torque converter pilot. Once input shaft clears bellhousing, carefully lower transmission while guiding it away from vehicle. Keep torque converter pressed firmly against transmission to prevent it from sliding off input shaft.
   ⚠️Transmission weight shifts significantly once it separates from engine. Maintain firm control of transmission jack at all times.
   ⚠Do not allow transmission to tilt or hang on input shaft. This can damage input shaft seal or bushing in crankshaft.
9. 9

   Inspect and prepare for installation
   Inspect torque converter hub for wear or damage. Verify torque converter is fully seated in transmission pump by measuring distance from bellhousing face to torque converter mounting surface (should be recessed approximately 1/2 inch or more). Inspect engine-to-transmission dowel pins and ensure they are present and undamaged. Clean bellhousing mating surface on engine block. Inspect flywheel for cracks, heat damage, or excessive wear. Replace crankshaft rear main seal if any evidence of leakage. Apply small amount of high-temp grease to torque converter pilot hub.
10. 10

    Install transmission to engine
    Position transmission on jack and raise to engine. Ensure torque converter remains fully seated in pump. Align transmission with engine dowel pins and carefully slide forward, keeping transmission level. Rotate torque converter as needed to align converter hub with crankshaft pilot and converter bolt holes with flywheel. Transmission should slide forward smoothly once aligned. Do not force or use bolts to pull transmission to engine. Install all bellhousing-to-engine bolts hand-tight first, then torque in criss-cross pattern.
    ⚠If transmission does not mate flush to engine, do not force it. Verify torque converter is properly seated and aligned.
11. 11

    Install torque converter bolts and starter
    Rotate crankshaft to access torque converter bolt holes through inspection cover opening. Apply threadlocker to new torque converter bolts if specified by manufacturer. Install all 6 torque converter-to-flywheel bolts and torque in star pattern. Reinstall torque converter inspection cover. Reinstall starter motor and connect electrical connections. Torque starter bolts to specification.
    Torque spec

    Flywheel Bolts95 Nm (70 lb-ft)
12. 12

    Reinstall crossmember and mount
    Raise transmission with jack to align with crossmember position. Install transmission mount to crossmember if removed. Position crossmember and install crossmember-to-frame bolts. Install transmission mount-to-crossmember nuts. Torque all mounting hardware to specification. Remove transmission jack once mount is secured.
    Torque spec

    Mounting Bolts76 Nm (56 lb-ft)
13. 13

    Reconnect driveshaft and linkages
    Remove rag from extension housing. Lubricate output shaft splines with small amount of ATF. Install driveshaft by inserting front yoke into transmission extension housing, aligning marks made during removal. Install driveshaft-to-differential flange bolts and torque to specification. Reconnect shift cable to transmission lever and install cable bracket. Adjust shift linkage if necessary.
14. 14

    Reconnect electrical and cooler lines
    Reconnect all transmission electrical connectors: main harness connector, speed sensors, and temperature sensor. Secure wiring harness to transmission case with clips. Connect transmission cooler lines and torque fittings to specification. Ensure lines are not kinked or contacting exhaust components.
15. 15

    Install transmission pan and fill fluid
    Install new transmission pan gasket on pan. Position pan to transmission and install all pan bolts hand-tight. Torque pan bolts in criss-cross pattern to specification. Install drain plug with new crush washer if equipped and torque to specification. Install dipstick tube into transmission. Lower vehicle. Fill transmission with ACDelco Dexron VI ATF through dipstick tube using pump or funnel. Initial fill approximately 5-6 quarts. Start engine and add fluid while checking level with engine running in Park on level ground. Total capacity is approximately 11.5 quarts including torque converter.
    Torque spec

    Pan Bolts20 Nm (15 lb-ft)

    Drain Plug42 Nm (31 lb-ft)

Reassembly

1. Reinstall any skid plates or undertray panels removed during disassembly
2. Reconnect negative battery cable to battery
3. Reset transmission adaptive learning values using scan tool if available
4. Check for fluid leaks around pan, cooler lines, and all connections before test drive

Verification

• With engine running at operating temperature, verify transmission fluid level is in FULL HOT range on dipstick
• Test drive vehicle and verify smooth operation through all gear ranges (Park, Reverse, Neutral, Drive, and manual shift modes)
• Verify no unusual noises, vibrations, or slippage during acceleration and deceleration
• Check for fluid leaks around transmission pan, cooler lines, shift shaft seal, and bellhousing after test drive
• Verify shift indicator matches actual gear selection in all positions
• Scan for diagnostic trouble codes and verify no transmission-related codes are present
• Verify proper operation of cruise control and any transmission-dependent systems

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