Rear Main Seal

Replace the rear main crankshaft seal by removing the transmission, flexplate, and rear main seal housing to prevent oil leaks at the crankshaft.

Warnings

Tools required

Parts

• Rear main crankshaft seal × 1 — Use OEM specification
• Rear main seal housing gasket × 1 — Use OEM specification
• Transmission pan gasket × 1 — Use OEM specification
• Oil drain plug crush washer × 1 — Use OEM specification
• Engine oil filter × 1 — Use OEM specification
• Flexplate bolts (if TTY) × 6 — Check service manual for TTY specification

Fluids

• Selenia Racing 10W-60 — 5.5 qt
• ZF Lifeguard 8 — 10 qt

Preparation

1. Ensure vehicle is on level surface and parking brake is engaged
2. Disconnect negative battery terminal and secure cable away from battery
3. Raise vehicle and support securely on jack stands at all four corners
4. Remove engine undertray and transmission shield panels
5. Place large drain pan under engine and drain engine oil completely, noting oil condition
6. Remove oil filter
7. Drain transmission fluid by removing transmission pan (save fluid if reusing)
8. Install engine support fixture or attach hoist to engine lifting points
9. Mark driveshaft-to-differential flange orientation with paint or marker

Procedure

1. 1

   Disconnect driveshaft and exhaust
   Remove the four bolts securing rear driveshaft flange to differential. Support driveshaft and lower it down. Disconnect exhaust system at mid-pipe connection and remove exhaust hangers as needed to allow transmission clearance. Lower or remove exhaust sections as required.
   Torque spec

   Mounting Bolts50 Nm (37 lb-ft)
2. 2

   Disconnect transmission electrical and cooler lines
   Locate and disconnect all transmission electrical connectors including shift solenoids, speed sensors, and temperature sensors. Label each connector for reassembly. Disconnect transmission cooler lines at transmission (capture fluid spillage). Cap or plug all open fittings to prevent contamination.
   Torque spec

   Electrical Connector Bolts7 Nm (5 lb-ft)

   Sensor Bolts11 Nm (8 lb-ft)
3. 3

   Remove transmission crossmember and supports
   Support transmission securely with transmission jack. Remove rear transmission mount bolts. Remove transmission crossmember mounting bolts and lower crossmember from vehicle. Ensure transmission jack is centered and secure before proceeding.
   ⚠️Transmission must be fully supported before removing crossmember. Verify jack stability before loosening final bolts.
   Torque spec

   Mounting Bolts50 Nm (37 lb-ft)
4. 4

   Separate transmission from engine
   Remove all torque converter access cover bolts. Mark torque converter-to-flexplate position. Remove torque converter-to-flexplate bolts by rotating crankshaft via front crank bolt (use 21mm socket). Remove all transmission-to-engine bell housing bolts, noting different lengths and positions. Carefully pull transmission straight back on transmission jack to separate from engine. Ensure torque converter remains with transmission.
   ⚠Torque converter must be held in place as transmission is separated. Use retaining strap or be prepared to support it to prevent falling.
   Torque spec

   Transmission-to-Engine Bolts55 Nm (41 lb-ft)

   Cover Bolts18 Nm (13 lb-ft)
5. 5

   Remove flexplate
   Install flywheel holding tool to prevent crankshaft rotation. Mark flexplate position relative to crankshaft for reassembly alignment. Remove all flexplate bolts in a criss-cross pattern. Remove flexplate from crankshaft, taking care not to drop it.
   ℹ️Inspect flexplate for cracks, heat damage, or damaged ring gear teeth. Replace if any damage is found.
   Torque spec

   Flexplate Bolts85 Nm (63 lb-ft)
6. 6

   Remove rear main seal housing
   Remove all rear main seal housing bolts in a progressive criss-cross pattern. Carefully pry housing away from engine block using plastic pry tools at designated pry points (check for casting bosses). Remove housing and old gasket. Do not damage aluminum mating surfaces.
   ⚠Do not use metal tools directly against aluminum surfaces. Use plastic or wood shims to prevent gouging.
   Torque spec

   Rear Main Seal Housing12 Nm (9 lb-ft)
7. 7

   Remove old rear main seal
   Using seal puller or carefully with seal removal tool, extract old rear main seal from housing. Inspect seal bore for damage, scoring, or burrs. Clean seal bore thoroughly with brake cleaner. Inspect crankshaft sealing surface for grooves, scoring, or damage that could prevent proper seal function.
   ⚠If crankshaft sealing surface is damaged beyond minor polishing, crankshaft replacement or machining may be required.
8. 8

   Clean all mating surfaces
   Thoroughly clean rear main seal housing mating surface on engine block using gasket scraper and RTV remover. Clean housing mating surface completely. Use brake cleaner and lint-free rags to remove all residue. Surfaces must be completely clean, dry, and free of oil contamination for proper gasket seal.
   ℹ️Even minor gasket material remnants can cause oil leaks. Take time to ensure perfect cleanliness.
   Torque spec

   Gasket Surface Bolts22 Nm (16 lb-ft)
9. 9

   Install new rear main seal
   Lightly lubricate new rear main seal lip with clean engine oil. Install seal into housing using seal installation tool or appropriately sized socket, ensuring seal is driven in square and to proper depth (typically flush or slightly recessed). Verify seal is fully seated around entire circumference.
   ⚠Seal must be installed perfectly square. Cocked or damaged seal lip will cause immediate oil leak.
10. 10

    Install rear main seal housing
    Install new housing gasket onto engine block (check for locating dowels or pins). Apply thin bead of appropriate RTV sealant if specified by manufacturer at gasket joints. Position rear main seal housing carefully over crankshaft, ensuring seal lip is not damaged during installation. Install all housing bolts finger tight, then torque in progressive criss-cross pattern to specification.
    ⚠Use extreme care sliding housing over crankshaft to avoid cutting or rolling seal lip. Seal damage during installation is common cause of immediate failure.
    Torque spec

    Rear Main Seal Housing12 Nm (9 lb-ft)

    Gasket Bolts21 Nm (16 lb-ft)
11. 11

    Install flexplate
    Clean crankshaft flange and flexplate mating surfaces with brake cleaner. Align flexplate to crankshaft using previously made alignment marks. Install flexplate bolts (use new bolts if TTY type). Install flywheel holding tool. Torque flexplate bolts to specification in star pattern, progressing in multiple stages.
    ℹ️If bolts are torque-to-yield (TTY) type, they must be replaced and cannot be reused. Verify specification in service manual.
    Torque spec

    Flexplate Bolts85 Nm (63 lb-ft)
12. 12

    Reinstall transmission
    Verify torque converter is fully seated in transmission (should have approximately 1/2 inch recess from bell housing face). Align torque converter with flexplate using alignment marks. Carefully raise transmission on jack and align with engine. Install all transmission-to-engine bolts and torque to specification. Rotate crankshaft and install torque converter-to-flexplate bolts to specification. Install torque converter access cover.
    ⚠Torque converter must be fully seated in oil pump before mating transmission to engine. Verify proper engagement by measuring recess depth.
    Torque spec

    Transmission-to-Engine Bolts55 Nm (41 lb-ft)

    Cover Bolts18 Nm (13 lb-ft)
13. 13

    Reinstall crossmember and reconnect components
    Install transmission crossmember and torque mounting bolts to specification. Remove transmission jack. Reconnect all transmission electrical connectors per labeling. Reconnect transmission cooler lines with new seals if applicable. Reinstall exhaust system and torque fasteners. Align and install driveshaft using alignment marks made during disassembly.
    Torque spec

    Mounting Bolts50 Nm (37 lb-ft)

    Electrical Connector Bolts7 Nm (5 lb-ft)

    Sensor Bolts11 Nm (8 lb-ft)
14. 14

    Refill fluids and final checks
    Install new oil drain plug crush washer and install drain plug, torquing to specification. Install new oil filter. Fill engine with 5.5 quarts of Selenia Racing 10W-60 oil. Fill transmission with 10.0 quarts of ZF Lifeguard 8 fluid through fill tube. Reinstall all undertray panels. Lower vehicle from jack stands.
    Torque spec

    Oil Drain Plug35 Nm (26 lb-ft)

Reassembly

1. Reconnect negative battery terminal
2. Start engine and verify no oil leaks at rear main seal area (check immediately and after 5 minutes of operation)
3. Check transmission fluid level with engine at operating temperature and follow ZF level check procedure
4. Verify no transmission fluid leaks at cooler lines or pan
5. Test drive vehicle through all gears to verify proper transmission operation
6. Recheck engine oil level after test drive and top off if necessary

Verification

• With engine running, inspect rear main seal area from underneath for any oil seepage (should be completely dry)
• After 50-100 miles of driving, recheck oil level and inspect seal area again for delayed leaks
• Verify no transmission shifting issues or unusual noises
• Verify driveshaft does not vibrate (proper alignment to original marks)
• Monitor oil consumption over next 500 miles to confirm seal is functioning properly

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