How Much Does it Cost to Fix a Rear Main Seal Leak?

A rear main seal leak is a common issue that many vehicle owners encounter at some point in their car’s lifespan. It’s a problem that, if left unaddressed, can lead to more significant engine issues and costly repairs. In this detailed 2000-word blog post, we will explore everything you need to know about fixing a rear main seal leak, including the cost, the repair process, considerations, and preventative measures.

How Much Does it Cost to Fix a Rear Main Seal Leak?

The cost to fix a rear main seal leak can vary widely depending on factors like the vehicle’s make and model, labor rates, repair method, and additional repairs needed. On average, it may range from $500 to $1,200, but costs can exceed $2,000 for more complex repairs or luxury vehicles.

Factors Affecting CostAverage Cost Range
Vehicle Make and Model$500 – $2,000+
Labor Costs (Hourly Rates)Varies by Location
Parts Cost (Rear Main Seal and Gaskets)$50 – $150
Repair Method (Engine or Transmission)Varies
Additional Repairs (if needed)Varies
Total Estimated Cost$500 – $2,000+

Understanding the Rear Main Seal

The rear main seal is a critical component of your vehicle’s engine. It is situated at the rear of the engine, where the crankshaft exits the engine block. Its primary function is to prevent engine oil from leaking out of the crankshaft as it spins and to keep contaminants from entering the engine.

Signs of a Rear Main Seal Leak

Identifying a rear main seal leak early is essential to prevent further damage to your engine. Common signs of a rear main seal leak include:

  1. Oil Spots Under the Vehicle: Puddles or spots of oil under your parked vehicle are a clear indicator of a leak.
  2. Low Engine Oil Levels: Frequent need to top up engine oil due to low levels.
  3. Burning Oil Smell: The smell of burning oil when the engine is running.
  4. Visible Oil on the Bellhousing: The bellhousing, which houses the transmission, may have visible oil residue.
  5. Sluggish or Noisy Transmission: If oil reaches the transmission, it can affect its performance, leading to sluggishness or noise.

The Cost of Fixing a Rear Main Seal Leak

The cost of fixing a rear main seal leak can vary widely depending on several factors:

  1. Vehicle Make and Model: The type of vehicle you have can significantly impact the cost. Luxury or high-performance vehicles often require more labor and specialized parts, increasing the overall expense.
  2. Labor Costs: Labor costs are a significant part of the repair expense. Labor rates vary by location, and some repair shops charge higher hourly rates than others.
  3. Parts Cost: The price of the rear main seal itself can vary based on the vehicle’s make and model. Additionally, other parts may need replacement, such as the oil pan gasket or the transmission fluid, which can add to the cost.
  4. Repair Method: There are two primary methods for fixing a rear main seal leak: replacing the seal in the vehicle or removing the engine or transmission for better access. The latter method is more labor-intensive and, therefore, more expensive.
  5. Additional Repairs: In some cases, while fixing the rear main seal, other issues may be discovered, such as a damaged flywheel or crankshaft. These additional repairs can significantly increase the overall cost.
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Repairing the Rear Main Seal: The Process

The repair process for a rear main seal leak involves several steps:

  1. Diagnosis: A mechanic will first confirm that the leak is indeed from the rear main seal and not another source. This may involve cleaning the area and monitoring for fresh oil leaks.
  2. Draining Engine Oil: The engine oil is drained to access the rear main seal.
  3. Accessing the Seal: Depending on the vehicle’s design, the mechanic will either remove the transmission or the engine to access the rear main seal.
  4. Seal Replacement: The old seal is removed, and a new one is installed. In some cases, the crankshaft may need to be removed or slightly lowered to facilitate seal replacement.
  5. Gasket Replacement: It’s common to replace the oil pan gasket, rear main seal cover gasket, and other gaskets while performing this repair.
  6. Reassembly: The engine or transmission is reassembled, and new transmission fluid and engine oil are added.
  7. Testing: The vehicle is started and tested for leaks. The mechanic will ensure that there are no leaks from the rear main seal or any other related components.

Considerations and Preventative Measures

  1. Proactive Maintenance: Regular oil changes and engine inspections can help identify potential issues early and prevent rear main seal leaks.
  2. Quality Parts: When replacing the rear main seal, it’s crucial to use high-quality, OEM (Original Equipment Manufacturer) or equivalent parts to ensure a reliable repair.
  3. Choose a Reputable Mechanic: Selecting a trusted and experienced mechanic or repair shop is essential to ensure the repair is done correctly.
  4. Timing Belt Replacement: If your vehicle has a timing belt, consider replacing it at the same time as the rear main seal to save on labor costs.
  5. Inspect the Flywheel: During the repair, have the flywheel inspected for damage or wear, as addressing any issues now can prevent future problems.


Is it worth fixing rear main seal? Yes, it’s worth fixing a rear main seal leak to prevent further engine damage and oil loss, which can lead to costly repairs if left untreated.

Is it bad to drive with a leaking rear main seal? Driving with a leaking rear main seal is not recommended, as it can lead to engine damage and low oil levels, potentially causing more expensive repairs.

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How much does it cost to replace a rear main seal? The cost to replace a rear main seal varies but typically ranges from $500 to $2,000 or more, depending on factors like vehicle type and additional repairs.

Does rear main seal leak fix work? Yes, fixing a rear main seal leak is effective when done correctly by a professional mechanic using high-quality parts.

How do I stop my rear engine seal from leaking? Stopping a rear main seal leak requires professional repair. There are no effective DIY methods to permanently stop the leak.

Can a rear main seal leak cause transmission problems? Yes, a rear main seal leak can affect the transmission if oil contaminates the transmission fluid, potentially leading to transmission issues.

How common is rear main seal leak? Rear main seal leaks are relatively common in older vehicles or those with high mileage, but not all vehicles experience this issue.

How long can you go with a rear main seal leak? You should address a rear main seal leak as soon as possible to prevent further damage. Continuing to drive with a leak can lead to more costly repairs.

How many hours does it take to replace a rear main seal? The labor hours required to replace a rear main seal can vary widely but typically range from 5 to 8 hours, depending on the vehicle’s design and accessibility.

What causes a rear main seal to go out? Common causes of a rear main seal failure include age, wear and tear, heat, high mileage, and engine vibrations.

Why is a rear main seal so expensive? The expense of replacing a rear main seal is due to the labor-intensive process, as it often involves removing the engine or transmission for access.

Do you have to remove the engine to replace a rear main seal? In many cases, yes. Access to the rear main seal often requires removing the engine or transmission, which makes the repair labor-intensive.

Is BlueDevil rear main seal a permanent fix? BlueDevil and similar products are temporary solutions that may stop the leak temporarily, but they are not considered permanent fixes. Professional repair is recommended for a lasting solution.

How do I know if my rear main seal is bad? Signs of a bad rear main seal include oil spots under the vehicle, low oil levels, a burning oil smell, visible oil on the transmission bellhousing, and sluggish or noisy transmission.

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Does a rear main seal leak engine oil? Yes, a rear main seal leak results in engine oil leaking from the rear of the engine, which can lead to various issues if not addressed.

Does BlueDevil ruin your engine? BlueDevil and similar products are generally safe when used according to instructions. However, they are not permanent fixes and should not be relied upon for long-term repair.

Can I replace a rear main seal myself? Replacing a rear main seal is a complex and labor-intensive task. It’s recommended to have it done by a professional mechanic unless you have advanced automotive repair skills.

Will thicker oil stop a rear main seal leak? Using thicker oil may slow down a rear main seal leak but is not a permanent solution. Professional repair is necessary for a lasting fix.


Fixing a rear main seal leak is a necessary repair to prevent further engine damage and maintain your vehicle’s performance. While the cost can vary based on several factors, it’s crucial to address the issue promptly to avoid more extensive and expensive repairs down the road. By understanding the signs of a rear main seal leak, the repair process, and taking preventative measures, you can keep your vehicle running smoothly and avoid costly engine damage.

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