Replacing Mazda 3 Oil Pan: Step-By-Step Guide

Replacing the oil pan on a Mazda 3 can be a complex task. The oil pan is located at the bottom of the engine and is responsible for holding the engine oil. While it is possible to replace the oil pan yourself, it is important to exercise caution as it can be a dangerous task. The average cost for a professional to replace a Mazda 3 oil pan is between $734 and $816, with labour costs estimated between $314 and $396, and parts typically priced around $420. This article will provide a step-by-step guide on how to replace the oil pan on a Mazda 3, ensuring safety and efficiency.

Mazda 3 Oil Pan Replacement Characteristics

Remove the battery, battery tray, and PCM component

To remove the battery, battery tray, and PCM component of a Mazda 3, follow these steps:

First, remove the battery. This will grant you access to the battery box and the PCM connectors. Then, to remove the PCM connectors, you must first remove the cover to the ECU and harness. With the cover removed, you will notice a white/beige/tan U-shaped clip on the harness. This is the lock. Take a flat-head screwdriver and gently wedge it between the clip and the harness block. Now, gently pry on the screwdriver towards the battery box, pulling the lock out and up. You will likely have to pull the lock the rest of the way up by hand. Be very gentle, as this part requires zero force and is very easy to break if you are too rough. With the lock removed, you can now pull the harness off.

With the PCM connectors disconnected, you can now remove the battery box. There are a couple of bolts at the bottom of the box that need to be removed, and then the box can be taken out.

It is important to note that working on your car can be dangerous, especially if it is not securely supported on safety stands. Always make sure your car is securely supported before beginning any work. Additionally, hot engines and engine oil can cause severe burns, so always be sure to allow your engine to cool before beginning any work.

Drain the engine oil

To drain the engine oil on a Mazda 3, you will need to locate the oil drain plug. This can be found on the underside of the engine, typically towards the back. Place a suitable container to catch the drained oil underneath the plug. You may need to raise the car to gain access to the drain plug. Ensure the car is on level ground and securely supported.

Once you have located the drain plug, you will need to remove it. Place your container to catch the oil directly under the plug. Have some rags ready to wipe away any oil that may spill. Using the correct size wrench or socket, loosen and remove the drain plug. Be careful not to strip the threads as you remove it. Set the plug aside in a clean place, as you will need to reinstall it later.

Allow the oil to drain completely. This may take several minutes. Once the oil has drained, you can reinstall the drain plug. Ensure the drain plug's gasket or washer is in good condition. If not, replace it with a new one. Thread the drain plug back into place by hand, ensuring it is properly aligned and not cross-threaded. Tighten the drain plug with your wrench, but be careful not to overtighten it. Check your Mazda 3 owner's manual for the correct torque specification.

After the drain plug is securely tightened, you can lower the vehicle if it was raised. Check the engine oil level with the dipstick to ensure it is below the "Full" mark. At this point, you can proceed to the next steps of replacing the oil pan on your Mazda 3.

Remove the A/C compressor

To remove the A/C compressor from a Mazda 3, follow these steps:

Firstly, some important safety information. It is illegal to vent refrigerant into the atmosphere, so always have your refrigerant recovered by a licensed professional. Some shops will put the refrigerant back in for you at little or no additional cost.

Now, to remove the A/C compressor:

• Disconnect the negative battery cable.
• Discharge the refrigerant.
• Remove the aerodynamic under cover No.2.
• Remove the drive belt.
• Remove the water hose bracket. Always plug open fittings immediately after removing any refrigeration cycle parts to avoid malfunction.
• Remove the clip (MZR 2.0).
• Disconnect the connector.
• Remove bolt A.
• Remove the cooler hose (LO).
• Remove the cooler hose (HI).
• Remove bolt B.
• Remove the A/C compressor, being careful not to spill any compressor oil.

To reinstall the A/C compressor, follow the above steps in reverse order.

Remove the ATF oil cooler

To remove the ATF oil cooler on a Mazda 3, follow these steps:

Firstly, locate the OEM transmission oil cooler. This is usually a cylinder-shaped cooler located next to the transmission. It is approximately the size of a tuna can and has one inlet and one outlet for oil.

Next, attach a clear vinyl tube to the "output" nipple of the ATF oil cooler. Ensure that the other end of the tube is placed in a container that can hold a couple of gallons of fluid. This will catch the old transmission fluid.

Now, start your Mazda's engine and put the car into drive. This will allow the fluid to flow through the torque converter. You may need to depress the brake and set the parking brake first. With the car running, the old fluid will be pumped out of the ATF oil cooler and through the vinyl tube into the container. Continue this process until approximately 3 quarts of fluid have been removed.

Once you have removed 3 quarts of fluid, turn off the engine and refill the transmission fluid to the correct level through the dipstick hole.

Finally, reinstall the transmission line and put everything back together. Ensure that all connections are secure to avoid leaks.

Reinstall in reverse order

To reinstall your Mazda 3's oil pan, you will need to follow these steps in reverse order:

• Tighten the bolts securing the engine and transaxle. Start from the bottom of the transaxle and work your way up. For MTX, tighten the bolts to 3.8-5.3 kgfm or 28-38 ft-lbf. For ATX, tighten to 3.9-5.3 kgfm or 29-38 ft-lbf.
• Tighten the four engine front cover bolts in the specified order. Torque to 8.1-12 kgfm or 71-97 in-lbf.
• Tighten the oil pan bolts in the order shown in the figure. Torque to 1.8-2.3 kgfm or 13-16 ft-lbf.
• Install the oil pan to the cylinder block.
• Apply silicone sealant to the oil pan along the inside of the bolt holes.
• Apply silicone sealant to the front edge of the oil pan and the engine front cover where they attach.
• Apply a generous amount of silicone sealant to the engine front cover where the oil pan fits into place. Also, apply an extra amount (a ball of approximately 5mm or 0.2 inches in diameter) of silicone sealant to the corners of the engine front cover and the cylinder block.
• Completely clean and remove any oil, dirt, sealant, or foreign material from the cylinder block, engine front cover, and oil pan.
• When reusing the oil pan installation bolts, clean any old sealant from them.
• Refill with the specified type and amount of engine oil.
• Start the engine and confirm that there is no oil leakage. If there is, repair or replace the applicable part.
• Inspect the oil level.

Please note that you should always refer to your Mazda 3 service manual for the most accurate and up-to-date instructions, as they may vary depending on the model year and specific engine type of your vehicle.

Frequently asked questions