Sealing Bmw E46 Oil Pan Gasket: External Fix

The oil pan gasket on BMW E46 models tends to dry out and leak over time. To seal the oil pan gasket from the outside, you will need to replace it and reseal the bottom of your crankcase. This involves removing the oil pan, cleaning it, and installing a new gasket. The process can be complex and time-consuming, requiring the removal of multiple parts and careful attention to safety. It is recommended to have your vehicle aligned after completing the repair.

Clean the area around the oil pan and crankcase

To clean the area around the oil pan and crankcase, you will need shop rags, a detergent that breaks down oil (such as Simple Green), and some plastic or composite scrapers. It is important to avoid using metal tools as the engine is made of soft aluminium, and metal tools will nick the metal.

First, use the plastic scraper to remove large amounts of oil from the flat surfaces. Spray some detergent on the surface and wipe with a shop cloth or paper towel. For areas that are harder to reach, such as the fins of the oil pan, spray the detergent between the fins and push a shop rag between them using one of the plastic scrapers.

You can also use the plastic scraper to remove the old oil pan gasket. Hold the scraper at a steep angle and scrape the gasket away slowly. Alternatively, you can chip at the gasket by holding the scraper a few inches away and quickly jabbing at the gasket like an ice pick. Once most of the gasket is removed, use a corner of the scraper to remove the remaining bits.

After cleaning, be sure to rinse the area with water and dry it thoroughly before proceeding with any repairs or replacements.

Confirm the leak is not from the oil filter housing

Confirming that the oil leak is not from the oil filter housing is a crucial step in maintaining your BMW E46. Here are some detailed instructions to help you through the process:

Step 1: Locate the Source of the Leak

Oil leaks can be tricky to pinpoint, especially when the oil drips down the engine to the oil pan. Start by looking for any oil-covered areas on the engine. The cleanest oil-covered area is often the source of the leak. This process may require some patience and a keen eye for detail.

Step 2: Check the Oil Filter Housing Gasket

The oil filter housing gasket is a common source of oil leaks on the BMW E46. Over time, this rubber gasket can harden and leak. To inspect it, remove the oil filter housing lid using a 36mm socket. If you notice any oil leakage around the sealing O-ring, the gasket is likely the culprit.

Step 3: Inspect the VANOS Line

In addition to the oil filter housing gasket, the VANOS line connected to it is another potential leak point. Remove the VANOS oil line using a 19mm wrench and observe if there is any oil leakage. Make sure to cover the line and opening to prevent dirt from entering the system.

Step 4: Check the Engine Sealing Surface

With the oil filter housing removed, clean the engine sealing surface and inspect the alignment dowels. These dowels help align the housing during reinstallation. Ensure they are in good condition and installed correctly. A damaged or misaligned dowel can cause an oil leak even with a new gasket.

Step 5: Verify Other Components

If the oil filter housing and VANOS line do not appear to be the sources of the leak, other components may be at fault. These can include the power steering pump, alternator, oil pressure sensor, or oil temperature sensor. Carefully inspect these parts for any signs of oil leakage or damage.

Remember, it is essential to address oil leaks promptly to prevent severe engine damage or failure. If you are unsure about the source of the leak or how to proceed with repairs, it is best to consult a BMW specialist or a trusted mechanic.

Remove the oil pan

To remove the oil pan from your BMW E46, you'll need to set aside a full day, and prepare a range of tools, including a jack, wrenches, and sockets. Here's a step-by-step guide:

Prepare the Vehicle:

• Jack up the front of your BMW E46 and remove the engine splash shield and reinforcement plate.
• Drain the engine oil.

Remove Components for Access:

• Remove the expansion rivets from the intake air duct using a small flat-head screwdriver and needle-nose pliers.
• Detach the intake air duct from the radiator support and remove the cooling fan shroud.
• Remove the drive belt from the alternator and power steering pulleys.
• Detach the air filter housing assembly and disconnect the airflow meter electrical connector. Loosen the airflow meter clamp and disconnect the duct.
• Pull the vacuum hose connector out of the intake air duct.
• Disconnect the electrical connector at the intake resonance valve and remove it using two T40 Torx fasteners.
• Loosen the hose clamps and remove the intake air ducts from the throttle housing.
• Remove the engine oil dipstick tube and pull the dipstick out of the oil pan.

Support the Engine:

Use an engine support or hoist to securely hold the engine.

Remove Components Connected to the Oil Pan:

• Detach the power steering pump from the crankcase by removing the fasteners.
• Remove the E10 steering coupler fastener and pull the steering shaft out of the coupler.
• Disconnect the oil level sensor electrical connector.
• Remove the lower engine mount nut by working through the hole in the front control arm.
• Remove the front sway bar bushing fasteners, control arm bushing fasteners, and front subframe fasteners.
• Slowly lower the subframe, ensuring no components are snagged, and unclip the power steering hose.
• Detach the transmission cooler line mount from the engine by removing the 10mm bolt and the 13mm bolt holding the mounting bracket to the crankcase.

Remove the Oil Pan Fasteners:

• Remove the E10 fastener from the left side of the oil pan and unclip the oil level sensor wiring harness.
• Remove the two E10 fasteners from the transmission bell housing.
• Remove all the oil pan fasteners, including the hidden ones up through the holes in the rear of the oil pan. There are a total of twenty-five 10mm fasteners to be removed.

Lower and Remove the Oil Pan:

With all the fasteners removed, carefully lower and remove the oil pan from the engine. Clean the oil pan thoroughly, especially the sealing surface, being cautious not to create nicks or scratches that could lead to leaks. Also, clean the engine side of the oil pan gasket sealing surface.

Clean the oil pan and engine side of the oil pan gasket sealing surface

To clean the oil pan and engine side of the oil pan gasket sealing surface, you will need to remove the oil pan. This is a time-consuming process that requires a range of tools and a good deal of automotive knowledge.

First, you will need to drain the engine oil. You will also need to remove the air filter housing assembly, the cooling fan shroud, the drive belt from the alternator and power steering pulleys, and the dipstick tube. You will then need to support the engine using a hoist or engine support bar.

Next, you will need to remove the power steering pump, the steering shaft, and the oil level sensor electrical connector. You will also need to remove the front sway bar bushing fasteners, the front control arm bushing fasteners, and the front subframe fasteners. With all the subframe components and fasteners removed, you can lower the subframe and remove the transmission cooler line mount from the engine.

Now you can remove the oil pan fasteners. There are 25 10mm fasteners that need to be removed. With all the fasteners out, you can lower and remove the oil pan from the engine. Once the oil pan is removed, clean it thoroughly—especially inside and the sealing surface, taking care to avoid creating nicks or scratches that might cause leaks. Also, clean the engine side of the oil pan gasket sealing surface.

To clean the oil pan and the sealing surface, you can use a plastic or composite scraper to remove large amounts of oil. You can also use a detergent that breaks down oil, such as Simple Green, and a shop cloth or paper towel to wipe away any remaining oil. Be sure to choose a cleaner that doesn't leave any residue or oily finish, and always wear the proper protection on your hands and eyes.

Apply a small amount of RTV sealant to the engine crankcase halves

When sealing the crankcase halves, it is important to ensure that they are free from engine oil. Before installing the new gasket, apply a small amount of RTV sealant to the engine crankcase halves. RTV silicone (room-temperature-vulcanizing silicone) is a type of silicone rubber that cures at room temperature and is commonly used in the automotive industry as an adhesive and sealant. It is available as a one-component product or as a mixture of two components: a base and a curative. RTV silicones can cure with a platinum or tin compound catalyst, such as dibutyltin dilaurate.

The sealant should be applied to the four corners of the engine, specifically the timing cover and end cover. This step is crucial in ensuring that the oil pan gasket is properly sealed and preventing future leaks. It is important to note that RTV silicone should not be applied to the gasket itself, as it can cause slipping during tightening.

Frequently asked questions