How To Replace a Leaking Valve Cover Gasket

Introduction

This tutorial will guide you through the process of replacing a leaking valve cover gasket, specifically for a 1999 Miata 1.8. Valve cover gaskets are common culprits for oil leaks and replacing them can be a straightforward DIY task with basic tools. The techniques outlined here can be applied to many vehicles, making this a valuable skill for any car enthusiast.

Step 1: Gather Your Tools and Materials

Before starting, ensure you have the following items:

• Brake cleaner
• Rags for cleaning
• Basic hand tools (sockets, wrenches)
• RTV sealant (silicone gasket maker)
• New valve cover gasket
• Replacement PCV valve (optional)

Tip: Place a piece of cardboard under your work area to catch any debris that may fall while cleaning.

Step 2: Prepare the Work Area

• Clean the Valve Cover: Use brake cleaner to blow off any dirt or debris from the valve cover. This prevents contaminants from falling into the engine when you remove the cover.

Step 3: Remove Components Attached to the Valve Cover

• Start by disconnecting spark plug wires. If they are not numbered, label them for easy reinstallation.
• Remove any additional components attached to the valve cover, such as:
  • PCV valve (handle carefully if brittle)
  • Hoses connected to the valve cover
  • Electrical connectors
• Tip: Organize bolts as you remove them to avoid confusion during reassembly.

Step 4: Unbolt the Valve Cover

• Remove the bolts securing the valve cover. Work from the outer bolts inward to avoid warping the cover.
• After unbolting, double-check that no bolts are left before attempting to remove the cover.
• Use a small pry bar to gently lift the valve cover without damaging the cylinder head.

Step 5: Clean the Mating Surfaces

• Scrape off any old RTV and debris carefully to avoid dropping pieces into the engine.
• Inspect the valve cover for cracks or damage that could cause future leaks.

Step 6: Install the New Gasket

• Test Fit: Place the new gasket on the valve cover to ensure proper alignment.
• Apply a thin layer of RTV sealant in the corners and around dramatic turns of the gasket to enhance sealing.
• Carefully position the gasket into the channels of the valve cover, ensuring it is fully seated.

Step 7: Reinstall the Valve Cover

• Position the valve cover back onto the engine.
• Start the bolts by hand to avoid cross-threading, then snug them down.
• Follow the manufacturer's torque sequence and specifications. For the Miata, the sequence is:
  1. Torque the bolts in the specified order.
  2. Use a torque wrench set to 43-78 inch-pounds (55 inch-pounds recommended).

Step 8: Reattach All Components

• Reconnect all hoses, electrical connectors, and spark plug wires in their correct positions.
• Replace the PCV valve if you have a new one.

Step 9: Final Cleanup

• Clean any residual debris or oil that may have fallen during the process.
• Allow any brake cleaner to evaporate before starting the engine.

Conclusion

Replacing a valve cover gasket is a manageable task that can prevent further oil leaks in your vehicle. Make sure to double-check all connections and the tightness of bolts after installation. Regular maintenance, including checking for leaks and replacing worn components like the PCV valve, can help keep your engine running smoothly. If you encounter any issues or want to learn more about diagnosing oil leaks, consider watching additional tutorials or consulting your vehicle's repair manual.