Tapping A Miata Oil Pan: The Easy Way

Tapping a Miata oil pan can be a daunting task, but with careful preparation and the right tools, it is achievable. The process involves drilling and tapping a hole in the oil pan, often for the installation of a turbo return line. It is essential to take precautions to prevent metal shavings from falling into the oil pan and causing damage. This can be done by greasing the drill bit and tap, using compressed air to blow out shavings, and flushing the pan with mineral spirits. Some people also choose to weld a thicker piece of metal or a bung to the oil pan before drilling and tapping to provide more thread depth and strength. It is also important to be aware of the location of the oil pickup tube and take measures to avoid damaging it during the drilling process.

Drilling and tapping the oil pan with the engine in the car

Drilling and tapping the oil pan with the engine still in the car is possible but can be difficult. Here is a step-by-step guide:

Step 1: Preparation

• Ensure your car is stable and secure. Use 4 sturdy jack stands and give the car a good shake once they are in place to ensure stability.
• Gather your tools: a drill, a tap wrench, electrical tape, a smaller bit for a pilot hole, grease, paper towels, Q-tips, and mineral spirits.
• Identify the location for the hole. Choose a spot that is as high as possible without interfering with your air conditioning compressor.

Step 2: Drill the Pilot Hole

• Cover your drill bit in grease to help control the shavings.
• Drill slowly and carefully, re-greasing the bit often.
• Stop drilling when you have a decent pilot hole to locate your larger drill bit.

Step 3: Drill the Hole

• Use compressed air to blow the bits and shavings out of the oil pan hole. Unscrew the oil drain valve and attach your air supply.
• Drill with care, taking your time and using lots of grease and paper towels to manage the shavings.
• Clean up the edges of the hole.

Step 4: Tap the Hole

• Grease the tap to trap the shavings.
• Line up the tap at the desired angle and start turning. Remember to cut, remove the tap, clean, and re-grease regularly.
• Sink the tap, leaving only 2-3 threads visible outside the pan to keep a safe distance from the oil pickup.

Step 5: Clean and Install Fitting

• Use a Q-tip or your finger, dipped in grease, to fish around inside the hole and remove any remaining shavings.
• Flush the pan with mineral spirits.
• Install the fitting using thread sealant, high-temp RTV, or JB Weld. Teflon tape is not recommended as it may melt.

This process is challenging but can be completed successfully with care and patience.

Drilling and tapping the oil pan with the engine on a stand

• Prepare the engine stand: Ensure that the engine is securely mounted on a sturdy engine stand. You may need to adjust the stand's height or position to access the oil pan comfortably.
• Gather the necessary tools and materials: You will need a drill, a tap, grease or thread cutting oil, a shop vacuum or air compressor, and some rags or paper towels for cleanup.
• Mark the drilling spot: Identify the location on the oil pan where you need to drill and tap for the turbo oil return line. Make sure to choose a spot that is away from the oil pickup tube to avoid any damage.
• Drill the hole: Apply grease or cutting oil to the drill bit to catch the metal shavings. Start drilling slowly and stop frequently to wipe the drill bit and reapply grease. This process may take a few minutes, but it helps ensure that fewer shavings end up in the oil pan. Drill the hole at an angle if needed to improve access, but remember to keep the tap perpendicular when threading.
• Tap the hole: Similarly, apply grease or cutting oil to the tap and slowly thread the hole, stopping often to wipe away any shavings and reapply lubricant.
• Remove metal shavings: Use a shop vacuum or a low-pressure air compressor (5-10 psi) to remove any remaining metal shavings from the oil pan. You can also use bent Q-tips to reach into the pan and collect larger shavings.
• Flush the oil pan: Pour mineral spirits or similar solvents into the oil pan and let it drain out to remove any residual shavings. Repeat this process if necessary.
• Seal the fitting: Apply a sealant or thread locker to the threads of the fitting before screwing it into the tapped hole. This will help prevent leaks.
• Change the oil: Finally, change the oil and filter to ensure that any remaining contaminants are removed from the engine.

By carefully following these steps, you can successfully drill and tap your Miata's oil pan while it is on an engine stand, minimising the risk of metal shavings causing damage to your engine.

Removing the oil pan

Before beginning the process of removing the oil pan, it is crucial to gather the necessary tools and materials. These may include a drill, drill bits, a tap, grease, an air compressor, mineral spirits, a shop vacuum, and personal protective equipment such as gloves and eye protection.

Step 1: Assess the Approach

There are different approaches to removing the oil pan from a Miata. Some people suggest that the "safe" way is to pull the motor and remove the oil pan separately. This method involves removing the subframe and dealing with the adhesive on the pan gasket. Alternatively, others have found success in simply drilling and tapping the oil pan while it is still bolted to the car, which can be more convenient but may be more challenging. Assess your comfort level and choose the approach that best suits your skills and resources.

Step 2: Prepare the Area

Loosen any components that may interfere with your access to the oil pan, such as the A/C system. It is also important to mark the spot on the oil pan where you will be drilling to ensure accuracy.

Step 3: Drilling and Tapping

Begin by greasing the drill bit and tap to help catch any metal shavings generated during the process. Drill a pilot hole to get started, and remember that you don't need to keep the drill perfectly perpendicular to the pan; just make sure the tap is perpendicular when threading the final hole. Take your time and work carefully to avoid damaging any nearby components, such as the oil pickup tube.

Step 4: Managing Shavings

To minimise metal shavings from entering the oil pan, you can use an air compressor to blow low pressure through the hose, forcing shavings out. Alternatively, you can use a shop vacuum to collect the shavings as you drill. Another method is to use extra oil in the pan, which will help flush out the shavings when you drain the oil.

Step 5: Finalising the Process

After drilling and tapping the hole, you can install the fitting using thread locker, RTV Red, or JB Weld to secure it in place. Ensure that any grease or oil residue is cleaned from the area before proceeding.

Step 6: Removing the Oil Pan

Once the drilling and tapping process is complete and the fitting is secured, you can now focus on removing the oil pan. This typically involves supporting the engine and lowering the crossmember to access the pan. Be prepared for an involved task, as it can be comparable to removing the engine itself.

Step 7: Breaking the Seal

To separate the oil pan from the engine, you will need to break the seal between the pan and the windage tray. Use a tool like a stiff putty knife to carefully pry the pan away from the tray, being cautious not to bend the tray in the process.

Step 8: Clean and Inspect

With the oil pan removed, take the opportunity to clean the area and inspect for any damage or issues. Pay close attention to the oil pickup and tray, as well as the crank and rods, to ensure they are in good condition.

Using grease to prevent shavings

When tapping a Miata oil pan, it is important to prevent metal shavings from entering the pan. To do this, generously apply grease to the drill bit and tap. This will cause the shavings to stick to the bit and tap, preventing them from falling into the pan. It is also recommended to use low air pressure (around 5 psi) in the crankcase while drilling to force the shavings out of the pan. After drilling and tapping, the pan should be flushed with mineral spirits and oil to remove any remaining shavings.

• Apply grease to the drill bit.
• Drill a small pilot hole in the desired location on the oil pan.
• Apply low air pressure (around 5 psi) to the crankcase through the breather port to force shavings out of the pan.
• Continue drilling the hole, stopping frequently to clean the bit and reapply grease.
• Once the hole is drilled, apply grease to the tap and tap the hole.
• Install the fitting using threadlocker, RTV Red, or JB Weld to seal the hole.
• Flush the pan with mineral spirits and oil to remove any remaining shavings.
• Replace the oil and filter, and start the engine, allowing it to run for a few minutes.
• Drain the oil again and inspect for any remaining shavings.

By following these steps and using grease to capture the shavings, you can help ensure that no metal shavings are left in the oil pan, preventing potential damage to the engine.

Flushing the oil pan with mineral spirits

Mineral spirits can be used to flush the oil pan of your Miata. This process helps to remove sludge and other buildup from the pan, keeping your engine clean and running smoothly. Here are some detailed instructions on how to flush your Miata's oil pan with mineral spirits:

Before you begin, gather the necessary supplies: mineral spirits, a funnel, an old pan or container to catch the drained fluid, and safety gear such as gloves and eye protection. Work in a well-ventilated area to avoid inhaling fumes.

First, locate the oil pan drain plug. Place the container underneath the drain plug to catch the fluid. Remove the drain plug using the appropriate tool, such as a wrench or socket. Allow the oil to drain completely.

Once the oil has drained, replace the drain plug. Pour a generous amount of mineral spirits into the oil pan through the filler cap or opening. Use a funnel to avoid spills. Start the engine and let it run for a few minutes. The mineral spirits will mix with the remaining oil and sludge, breaking it down and loosening any buildup.

After running the engine, turn it off and allow the mineral spirits mixture to settle for a few minutes. Then, remove the drain plug again and let the fluid drain into the container. This fluid will be a mixture of mineral spirits, oil, and sludge. Dispose of it properly according to your local regulations.

Rinse the oil pan with fresh mineral spirits and drain it again. Repeat this rinsing and draining process several times to ensure that all sludge and residue are removed. Finally, refill the engine with fresh oil and a new oil filter. Start the engine and check for any leaks.

Some precautions to keep in mind: Mineral spirits can be harsh on rubber seals and gaskets, so use it sparingly and avoid prolonged contact. Always wear gloves and eye protection when handling mineral spirits. Do not dispose of mineral spirits or oil-contaminated fluids down the drain; take them to a designated disposal facility.

By following these steps, you can effectively flush your Miata's oil pan with mineral spirits, maintaining the cleanliness and performance of your engine.

Frequently asked questions