Seeing oil dripping between your engine and transmission? You might have a leaking rear main oil seal—a small part that can lead to major repairs if ignored.
The rear main seal prevents oil from leaking out the back of the crankshaft. It’s hidden deep inside the engine and often overlooked until serious signs appear.
In this guide, I’ll explain what a rear main seal is, how to recognize failure symptoms, how much it costs to replace, and whether it’s safe to keep driving.
What is a rear main oil seal?
ال rear main oil seal is a circular shaft seal located at the back of the engine block, around the crankshaft’s rear end. It seals the rotating crankshaft as it exits the engine to connect with the flywheel or flexplate.
Its job is simple but critical:
ل keep engine oil inside while the crankshaft rotates thousands of times per minute.
This type of seal is usually made of NBR or FKM rubber and installed in a two-piece housing or integrated block.
👉 Learn about crankshaft seals in general here: Crankshaft Oil Seal Guide
What are the symptoms of a rear main oil seal leak?
You may not notice a leaking rear seal until the leak becomes serious. Watch out for these symptoms:
- Oil spots or puddles beneath the bell housing area
- Excessive oil consumption with no external damage
- Wet or greasy flywheel housing
- Burning oil smell under the vehicle
- Transmission slipping due to oil-soaked clutch (manual)
- Darkened gasket area around the engine’s rear
If the leak is active, it will continue to worsen with time and vibration.
👉 Related read: Oil Seal Leaks: Causes and Fixes
How much does rear main seal replacement cost?
Replacing a rear main seal is labor-intensive. The seal itself is cheap—usually $10–30—but getting to it is another story.
| Vehicle Type | Estimated Cost (USD) |
|---|---|
| Passenger Car | $400–$800 |
| Pickup Truck | $500–$1000 |
| Commercial Vehicle | $1000–$1500 |
| Manual Transmission | Often higher due to clutch disassembly |
👉 Want to save cost? Use aftermarket seals like Toyota Oil Seals by Hengoseal—OEM match with better value.
Can I drive with a rear main oil seal leak?
Technically, yes—but it’s risky.
Driving with a leaking rear seal can:
- Drain your engine oil dangerously low
- Cause oil to soak the clutch or flywheel
- Lead to engine seizure or misfiring
- Increase repair costs if damage spreads
Unless the leak is extremely minor and monitored closely, we do not recommend driving long distances without repair.
How do you replace a rear main oil seal?
Here’s a simplified breakdown:
- Remove the transmission or transaxle
- Disconnect the flywheel or flexplate
- Unbolt the seal housing or rear cover
- Carefully remove the old seal
- Clean the crankshaft and bore area
- Lubricate the new seal’s lip
- Press in the new seal using a seal installer
- Reassemble all parts in reverse order
Professional installation is highly recommended due to complexity.
👉 For step-by-step tips: دليل تركيب مانع تسرب الزيت
خاتمة
The rear main oil seal may be small, but when it leaks—it’s no joke. Don’t wait for engine failure. Identify the leak, select the right seal, and get it replaced with a reliable aftermarket solution.
نداء للعمل
Need OEM replacement rear main oil seals? Hengoseal offers NBR/FKM options for TOYOTA, NISSAN, HONDA, and more. Fast shipping, low MOQ, and custom branding available.
📧 البريد الإلكتروني: [email protected]
📱 واتساب: +86 17622979498
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