Genuine Mazda Rear Crankshaft Oil Seal & Cover • LF01-11-310

Genuine Mazda LF01-11-310 Rear Crankshaft Oil Seal & Cover

Replacement Genuine Mazda rear crankshaft oil-seal cover for Mazda MX-5 Mk3, Mk3.5 and Mk3.75 NC models with 1.8 L8-VE or 2.0 LF-VE MZR petrol engines.

This assembly is fitted to the rear face of the cylinder block, immediately behind the flywheel or automatic-transmission drive plate. It supports and positions the rear crankshaft oil seal concentrically around the crankshaft flange.

The oil seal prevents engine oil escaping where the rotating crankshaft exits the cylinder block. The rigid rear cover also provides the correct mounting position and sealing interface between the rear of the engine block and the lower oil-pan area.

Age, heat cycles, crankshaft movement or incorrect previous installation can cause the seal lip to harden, wear or leak. Because the assembly is concealed behind the gearbox and flywheel, oil may first become visible from the lower bellhousing area.

One rear crankshaft oil-seal cover is fitted per engine, and this listing supplies one Genuine Mazda assembly.

• Part type: Rear crankshaft oil-seal cover assembly
• Common names: Rear main seal housing / rear engine cover
• Mazda catalogue description: Cover, Rear
• Location: Rear face of the cylinder block
• Position relative to transmission: Behind the flywheel or automatic drive plate
• Function: Supports and positions the rear crankshaft oil seal
• Rear crankshaft sealing element: Incorporated within the cover assembly
• Quantity fitted per engine: 1
• Quantity supplied: 1 rear cover assembly
• Mounting bolts included: No
• Flywheel or drive plate included: No
• Oil-pan sealant included: No
• Brand: Genuine Mazda
• Part No.: LF01-11-310
• Associated Mazda references: LF01-11-310A / 1F20-23-657 / 1F2023657U
• MX-5 fitment: Mk3, Mk3.5 and Mk3.75 NC 1.8 and 2.0 engines

Possible signs of a leaking rear crankshaft seal:

• Engine oil appearing from the lower bellhousing area
• Oil contamination inside the clutch bellhousing
• Oil reaching the clutch friction plate
• Clutch slip caused by engine-oil contamination
• Engine-oil level gradually falling without an obvious external leak
• Oil residue around the rear of the cylinder block or oil pan
• Visible damage or distortion after gearbox or flywheel removal

Fitment advice: This rear cover is used on the original Mazda MX-5 NC 1.8 L8 and 2.0 LF MZR engines. Confirm compatibility where the vehicle has received an alternative engine block, engine conversion or non-standard crankshaft assembly.

Diagnosis advice: Oil within the bellhousing area can originate from the rear crankshaft seal, the rear of the oil pan, the cylinder-block sealing joint or the gearbox input-shaft seal. Clean and inspect the area carefully before replacing components.

Other items to consider: Inspect the crankshaft sealing surface, flywheel or drive plate, clutch assembly, gearbox input-shaft seal, rear oil-pan joint, cover fasteners and surrounding cylinder-block sealing surfaces. A worn or grooved crankshaft sealing surface may prevent a new seal from operating correctly.

Useful tools / consumables: Transmission jack, flywheel holding tool, suitable socket set, calibrated torque wrench, sealant approved for the applicable Mazda engine joint, plastic gasket scraper, brake cleaner, lint-free cloths and suitable installation guides or sleeves for protecting the seal lip.

Difficulty guide: DIY Difficulty: Specialist / Advanced. The gearbox must be removed, followed by the clutch and flywheel or automatic drive plate. The seal and cover must be installed squarely without damaging or rolling the sealing lip.

Why Genuine Mazda? Genuine Mazda rear crankshaft covers are manufactured to match the original cylinder-block mounting pattern, crankshaft centre, sealing diameter and oil-pan interface. Correct concentricity and sealing geometry are essential for reliable operation around the rotating crankshaft.

What’s in the box: One Genuine Mazda rear crankshaft oil-seal cover assembly, part number LF01-11-310.

Installation notes: Remove the gearbox, clutch and flywheel or automatic drive plate in accordance with the applicable Mazda workshop procedure. Clean the rear of the cylinder block and inspect the crankshaft sealing surface for wear, corrosion or grooves. Remove all old sealant without damaging the aluminium mating surfaces. Apply sealant only to the specified joints and in the prescribed quantity. Protect the new seal lip during installation, position the cover squarely over the crankshaft and tighten its fasteners progressively to the applicable Mazda specifications. Allow any liquid sealant to cure as directed before refilling or operating the engine. Check carefully for leakage after reassembly.