How To Replace 5.0L Coyote Rear Main Seal (Also Works For 4.6L, 5.4L, 6.8L Engines)

Created by Tyler Rodriquez / 6 min read
Date Created: 8/21/2023
Last Updated: 2/9/2024

Today, we here at LMR walk you through the steps on how to replace a rear main seal on a Coyote-powered S197, but the same procedure works on most modular Ford engines.

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A leaking rear main seal is a problem that many Mustang owners face, but are not always sure on how to make the repair. Since you do have to drop the transmission to replace a main seal, the task can be quite intimidating. Today, we here at LMR walk you through the steps on how to replace a rear main seal on a Coyote-powered S197, but the same procedure works on most modular Ford engines.

Parts List:

Tool List:

  • Brake Clean & Towels
  • Fresh Engine Oil
  • RTV Silicone
  • Compressed Air
  • Vise
  • Large Metal Disc (This is to install the rear main seal into the retainer plate.)
  • Hammer
  • Drift Set
  • Regular Pry Bar Set
  • Hook-and-Point Pry Bar Set
  • Razor Blade or Gasket Scraping Tool
  • Ratcheting Wrench Set
  • 1/4" & 3/8" Socket Set
  • 1/4" Torque Wrench

Installation Instructions


Step 1: Prepare for the Job

For Mustangs with an automatic transmission, take note of the shifter linkage and automatic transmission cooler lines. Ensure all transmission-related components are already removed from the vehicle.


Step 2: Remove the Crankshaft Sensor Ring

Locate and remove the crankshaft sensor ring (also called a pulse ring or exciter ring).


Step 3: Remove the Separator Plate/Electrical Components

  • Disconnect the crankshaft position sensor electrical connection.
  • Loosen the sensor hold-down bolt with an 8mm ratcheting wrench.
  • Slide the sensor out of the retainer plate.
  • If needed, remove the block plug and clean the area with brake cleaner and towels.


Step 4: Remove the Retainer Plate

  • Loosen and remove the eight bolts securing the retainer plate (six on the engine block and two on the oil pan).
  • Use a hook and point pry bar to separate the retainer plate from the engine block.

Step 5: Clean the Area

  • Cover the oil pan with paper towels.
  • Remove old silicone from the engine block with a razor blade.
  • Clean the area with brake cleaner and towels.

Step 6: Clean and Inspect the Retainer Plate

  • Clean the retainer plate and its retaining bolts.
  • Brush the mating surface with a wire wheel and blow it with compressed air.

Step 7: Install the Rear Main Seal

  • Place the retainer plate face down on a workbench.
  • Align the new rear main seal by hand, ensuring it stays in place (gasket side facing you).
  • Put a thin metal disc larger than the seal over it.
  • Secure it in a large vise and close the vise to press the seal into place evenly, ensuring it's flush with the retainer plate's outside face.
  • Verify that the Garter spring is in place.

Step 8: Lubricate the Seal

  • Lubricate the seal lips with fresh engine oil or assembly grease.
  • Wipe the mating surface on the retainer plate with a clean towel.

Step 9: Apply Silicone

  • Apply an 1/8-inch bead of RTV silicone to the mating surfaces (inside of the bolt holes).
  • Apply a 5/16-inch bead of silicone to both sides of the oil pan where it meets the engine block.

Step 10: Reinstall the Retainer Plate

  • Position the retainer plate into place.
  • Use a small flathead screwdriver to verify that the seal's lip doesn't roll inward.
  • Hand-tighten all previously removed bolts.
  • Evenly tighten the bolts to fully seat the retainer plate.
  • Torque the bolts in a crisp cross pattern to 89 pound-inches first, then rotate an additional 45 degrees.
  • Torque the oil pan bolts using the same specs.

Step 11: Reconnect Sensors and Components

  • Reinstall the crankshaft position sensor.
  • Torque the bolt to 89 pound-inches.
  • Reconnect the electrical connection, ensuring it clicks.
  • Reinstall the crankshaft sensor ring in the correct orientation (teeth facing the engine).
  • Reinstall all transmission-related components.


That's it! You should now be able to successfully install a rear main seal in a Modular engine. If you are uncomfortable with this installation, we highly suggest seeking professional mechanical help. For everything, 1979-Present Mustang, keep it right here with the real Mustang enthusiasts,

About the Video

How To Replace 5.0L Coyote Rear Main Seal (Also Works For 4.6L, 5.4L, 6.8L Engines)

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Published on 2023-06-06
In this video, Landan explains the process of how to replace the rear main seal in a Ford 5.0L Coyote engine. The procedure shown in this video will also work with the other V8 engines int the Ford modular engine family because of the retainer plate design.
Thumbnail image of the author of this article, Tyler Rodriquez.

About the Author

Tyler has written content for Late Model Restoration for nearly 8 years, producing over 300 articles. As an avid New Edge fan, Tyler has owned 4 2004 Mustangs and an 88 Convertible Fox Body. Read more...