Victor Reinz Rear Crankshaft Seal – 81-20745-40

Quick Info

OEM-quality rear crankshaft oil seal (rear main seal) for BMW petrol and diesel inline engines.
Designed to prevent engine oil leaks between the crankshaft and transmission.

Description

Victor Reinz 81-20745-40 is a rear crankshaft seal installed at the transmission end of the engine.

This seal prevents engine oil from leaking past the rear of the crankshaft while maintaining proper sealing under high RPM and crankcase pressure conditions. Manufactured from FPM/Viton material for high temperature and long service life.

Supplied with mounting sleeve for correct installation.

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Deep Engine Compatibility Research

BMW Petrol Engines

✔️ M10
✔️ M20
✔️ M30
✔️ M40
✔️ M42
✔️ M44
✔️ M50
✔️ M52
✔️ M54

BMW Diesel Engines

✔️ M21
✔️ M41
✔️ M47
✔️ M51
✔️ M57

❌ NOT for:

• N47
• N57
• B47
• B57

The seal is primarily used across older BMW E-series inline engine platforms.

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Common BMW Models

3 Series

• E30
• E36
• E46

5 Series

• E28
• E34
• E39

7 Series

• E32
• E38

X Models

• E53 X5
• E83 X3

Other

• Z3
• Z4 E85
• E24 6 Series

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Part Numbers

• Victor Reinz: 81-20745-40
• BMW OE references:
  • 11141706785
  • 11142249533
  • 11142245364
  • 11141255012
  • 11141275161

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Technical Details

• Type: Rear crankshaft oil seal / rear main seal
• Position: Transmission end of crankshaft
• Inner diameter: 90mm
• Outer diameter: 110mm
• Width: 12mm
• Material: FPM / Viton
• Swirl direction: Left-hand twist
• Includes mounting sleeve

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Notes

• OEM-quality Victor Reinz sealing component
• Commonly replaced during clutch or gearbox removal
• Designed for long-life oil sealing performance

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Important

❗ Not a front crank seal
❗ Not for BMW modular N-series/B-series diesels
❗ Proper installation tool recommended

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Common issues when faulty

• Oil leak between engine and gearbox
• Oil contamination on clutch/flex plate
• Rear engine oil seepage
• Burnt oil smell from transmission area

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Fitment Summary

✔️ M47 / M57
✔️ M50 / M52 / M54
✔️ Older BMW inline petrol & diesel engines
❌ Not N47 / N57 / B57