Rear Main Seal

This procedure covers replacement of the rear main crankshaft seal on the 2018-2024 Honda Accord 1.5L Turbo, requiring transmission removal to access the seal housing.

Warnings

Tools required

Parts

• Rear main crankshaft seal × 1 — Use OEM Honda specification
• Oil drain plug crush washer × 1 — 94109-14000
• Transmission fluid × 1 — Honda DW-1 ATF
• Engine oil × 1 — Honda Genuine 0W-20
• Rear main seal housing gasket (if equipped) × 1 — Use OEM specification

Fluids

• Honda Genuine 0W-20 — 4 qt
• Honda DW-1 ATF — 8 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Disconnect negative battery terminal and wait 3 minutes for airbag system to discharge
3. Raise vehicle and support securely on jack stands at all four corners
4. Remove engine under cover and splash shields
5. Drain engine oil completely and remove oil filter
6. Drain transmission fluid by removing drain plug
7. Remove front wheels if additional working room needed
8. Install engine support fixture across engine bay to support engine weight

Procedure

1. 1

   Remove exhaust system components
   Disconnect exhaust system at the front flange. Remove exhaust hangers as needed to lower the front exhaust pipe away from the transmission. Support exhaust with wire or stands to prevent damage.
2. 2

   Disconnect driveshafts
   Remove the lower ball joint pinch bolts on both sides. Separate the outer CV joints from the steering knuckles by pulling the knuckles outward. Support the driveshafts with wire to prevent damage to the inner CV joint boots. Mark orientation if using mechanical ATF before removal.
   ⚠Do not allow driveshafts to hang freely as this can damage CV joint boots and internal components.
3. 3

   Disconnect electrical and mechanical connections
   Disconnect all electrical connectors from the transmission including vehicle speed sensor, shift solenoids, and reverse light switch. Disconnect shift cable from transmission. Remove any ground straps attached to transmission case. Label all connections for reassembly.
4. 4

   Remove transmission cooler lines
   Disconnect ATF cooler lines from transmission. Use flare nut wrenches to avoid rounding fittings. Plug lines and transmission openings immediately to prevent contamination and fluid loss. Have rags ready to catch residual fluid.
   ⚠ATF cooler lines are under slight pressure. Residual fluid will drain when disconnected.
5. 5

   Support and remove transmission mounts
   Position transmission jack under transmission and secure with safety chain. Remove rear transmission mount bolts. Remove any additional transmission support brackets. Verify engine is securely supported by engine support fixture before proceeding.
   ⚠️Transmission weighs approximately 100-120 lbs. Ensure transmission jack is properly positioned and secured before removing mounting bolts.
   Torque spec

   Mounting Bolts26 Nm (19 lb-ft)
6. 6

   Remove starter motor
   Disconnect starter motor electrical connections. Remove starter mounting bolts and remove starter from bell housing. Set aside in safe location. This provides access to upper transmission-to-engine bolts.
7. 7

   Remove transmission-to-engine bolts
   Remove all transmission-to-engine bolts. There are typically 4-5 bolts around the bell housing perimeter. Note location of any ground straps or brackets. Support transmission firmly on jack while removing final bolts.
   Torque spec

   Transmission-to-Engine Bolts55 Nm (41 lb-ft)
8. 8

   Separate and lower transmission
   Carefully pull transmission straight back away from engine to disengage torque converter from flexplate. Move slowly and keep transmission level. Once clear of alignment dowels, carefully lower transmission on jack. Guide around subframe and suspension components as needed.
   ⚠Do not allow transmission weight to hang on input shaft. This can damage torque converter, flexplate, or crankshaft.
9. 9

   Remove flexplate
   Use a flexplate holding tool or large screwdriver to prevent crankshaft rotation. Remove all flexplate bolts in a star pattern. Remove flexplate and set aside in clean area. Inspect flexplate for cracks or damaged ring gear teeth.
   ℹ️Mark flexplate orientation to crankshaft before removal to maintain balance during reassembly.
   Torque spec

   Flexplate Bolts85 Nm (63 lb-ft)
10. 10

    Remove rear main seal housing
    Remove all rear main seal housing bolts in a cross pattern. Carefully pry housing away from engine block using plastic pry points if provided. Clean all old gasket material from engine block and housing mating surfaces using plastic scraper. Inspect housing for cracks or damage.
    Torque spec

    Rear Main Seal Housing12 Nm (9 lb-ft)
11. 11

    Remove old rear main seal
    Use seal pick or small screwdriver to carefully pry old seal from housing. Work around perimeter evenly to avoid damaging housing bore. Clean seal bore thoroughly with brake cleaner and lint-free cloth. Inspect bore for scratches or damage that could cause new seal to leak.
    ⚠Do not scratch or gouge seal housing bore. Any damage will cause premature seal failure.
12. 12

    Install new rear main seal
    Apply thin coat of clean engine oil to new seal lip and outer diameter. Position seal squarely in housing bore with lip facing toward engine. Use rear main seal installation tool or appropriately sized large socket to drive seal evenly into housing until fully seated and flush. Verify seal is not cocked or damaged.
    ⚠Seal must be installed perfectly square. A cocked seal will leak immediately upon startup.
13. 13

    Install rear main seal housing
    Install new gasket on engine block or apply thin bead of Honda Bond or equivalent RTV to mating surface if gasket is not used. Position housing carefully over crankshaft and align with dowel pins. Install all bolts hand-tight, then torque in cross pattern to specification. Wipe away any excess sealant.
    ℹ️If using RTV sealant, allow proper cure time per manufacturer instructions before adding oil.
    Torque spec

    Rear Main Seal Housing12 Nm (9 lb-ft)
14. 14

    Reinstall flexplate
    Clean flexplate and crankshaft mating surfaces. Align flexplate to crankshaft using alignment marks made during removal. Install flexplate bolts hand-tight. Torque flexplate bolts in star pattern to specification. Use holding tool to prevent crankshaft rotation during tightening.
    ⚠Flexplate bolts are critical fasteners. Verify proper torque and follow star pattern sequence.
    Torque spec

    Flexplate Bolts85 Nm (63 lb-ft)
15. 15

    Reinstall transmission
    Ensure torque converter is fully seated in transmission pump (should have 2-3 distinct clicks when pushed in). Apply small amount of grease to torque converter hub splines. Raise transmission into position and align with engine dowel pins. Push transmission forward until bell housing contacts engine block. Verify torque converter hub engages flexplate properly. Install transmission-to-engine bolts and torque to specification in cross pattern.
    ⚠Torque converter must be fully seated in pump before installing transmission. Improper seating will cause transmission failure.
    Torque spec

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

Reassembly

1. Reinstall starter motor and torque mounting bolts to specification
2. Install transmission mounts and torque all mounting bolts to specification per torque database
3. Connect ATF cooler lines and torque fittings properly
4. Reconnect all electrical connectors and shift cable to transmission
5. Reinstall driveshafts into transmission and reconnect to steering knuckles
6. Reinstall exhaust system and torque flange bolts to specification
7. Install new oil drain plug crush washer and torque drain plug to 35 Nm (26 lb-ft)
8. Remove engine support fixture
9. Install new engine oil filter and fill with 4.0 quarts Honda Genuine 0W-20 oil
10. Fill transmission with Honda DW-1 ATF per manufacturer procedure (approximately 3-4 quarts initially)
11. Reinstall wheels if removed and torque lug nuts to specification
12. Reinstall splash shields and under covers
13. Reconnect negative battery terminal

Verification

• Start engine and verify no oil leaks from rear main seal area while engine idles
• Check transmission fluid level with engine at operating temperature and adjust as needed per Honda procedure
• Verify proper transmission operation through all gear ranges
• Road test vehicle and verify smooth shifting and no abnormal noises
• Re-check oil and transmission fluid levels after road test
• Inspect underneath vehicle for any fluid leaks after initial drive cycle
• Monitor oil consumption and check for leaks again after 100-200 miles of driving

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