Noticed oil puddles under your car or oil stains near the engine? It could be your crankshaft oil seal leaking—a small part that causes big problems if left untreated.
Crankshaft oil seals keep oil inside the engine while preventing contaminants from entering. Over time, they wear out due to heat, pressure, and rotation.
In this article, we’ll help you understand the function of a crankshaft seal, recognize failure symptoms, compare front vs rear seals, and choose the right aftermarket replacement.
What is a crankshaft oil seal?
A crankshaft oil seal is a circular rubber sealing element located at the front and/or rear end of the engine crankshaft. It prevents engine oil from leaking where the shaft exits the crankcase.
| Type | Location | Description |
|---|---|---|
| Front Crankshaft Seal | Near timing cover | Seals rotating shaft at pulley end |
| Rear Main Seal | Between engine and transmission | Seals rear of crankshaft housing |
We supply front and rear crankshaft seals in NBR and FKM, matching OEM quality standards.
👉 Explore our TOYOTA crankshaft oil seal options
👉 Or learn more in our TOYOTA Oil Seal Replacement Guide
What are the symptoms of a leaking crankshaft oil seal?
Leaking crankshaft seals can trigger multiple issues:
- Oil leaking from the front or rear of the engine
- Visible stains under the engine or bell housing
- Unusual engine noises or vibration
- Burning oil smell
- Low oil level over time
- Wet crankshaft pulley or flywheel housing
If the rear main seal fails, it may require removing the transmission—making early detection crucial.
How to replace a crankshaft oil seal?
Tools needed:
- Pulley puller or flywheel removal tool
- Oil seal installer or rubber mallet
- Socket set, sealant, and cleaning wipes
Steps:
- Disconnect battery and drain engine oil
- Remove pulley (front) or transmission (rear)
- Pry out the old seal carefully
- Clean the housing area
- Apply light oil to the new seal and press in evenly
- Reinstall removed components
- Refill oil and test engine
Professional installation is recommended for rear crankshaft seals due to difficulty.
If you’re sourcing replacement parts, check our Cross Reference Chart for compatible aftermarket options.
Can I use aftermarket seals for crankshaft replacement?
Yes—and they often offer better value.
At Hengoseal, our crankshaft seals are:
- Manufactured with precision to match OEM standards
- Available in FKM (high-temp) and NBR (standard)
- Compatible with TOYOTA, HONDA, MITSUBISHI, NISSAN, etc.
- Offered in flexible MOQ for both repairs and wholesale
👉 Check our TOYOTA crankshaft oil seal product page
👉 Read our Skeleton Oil Seal Guide to understand seal structure
Should I replace front and rear crankshaft seals together?
Not always. If only one side is leaking, you can replace just that seal.
However, during engine rebuilds, clutch replacement, or timing belt service, it's cost-effective to replace both.
We offer rear main seals and front crankshaft oil seals for most models.
If you’re unsure which part to choose, contact us with your OEM number or shaft dimensions.
Conclusion
A worn crankshaft oil seal can lead to serious oil leaks and engine issues. Replacing it with a high-quality aftermarket part ensures durability and peace of mind.
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Need a crankshaft oil seal for TOYOTA or other brands? We offer OEM replacements, fast lead time, and custom packaging.
📧 Email: [email protected]
📱 WhatsApp: +86 17622979498
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