Oil Pan Compatibility: N4 And N55 Engines Share The Same Design

The N55 engine oil pan is a topic of interest for BMW owners and car enthusiasts alike. While some sources suggest that the N54 and N55 oil pans are interchangeable, others provide detailed accounts of the challenges and modifications required to replace an N55 oil pan. This task involves more than just the oil pan itself, as it includes gaskets, bolts, sensors, pumps, and even the removal of the subframe. The N55 oil pan has also been compared to the S55 oil pan, with some people attempting to adapt the latter to fit the former. Overall, the N55 oil pan and its maintenance or replacement can be a complex process, requiring careful consideration and a range of specialised tools and parts.

N54 and N55 oil pans are interchangeable

The N54 and N55 oil pans are interchangeable. However, this is not always a straightforward process. While the oil pans themselves are the same, the bolt pattern on the N55 oil pan and bead plate may differ, requiring some adjustment. For example, one bolt hole may need to be repositioned, which can be achieved through long hole drilling.

Additionally, the power steering pump mounts to the oil pan on the E series but not on the F series, so this will need to be addressed during the swap.

The N54 and N55 oil pans are known to be interchangeable on a 135i, but some chassis may differ, such as the Z4 or AWD models.

When considering this swap, it is important to research and consult reliable sources and professionals to ensure a proper fit and avoid any potential issues or damage.

N55 oil pan gasket replacement is a challenging DIY task

One of the biggest challenges of this task is accessing all the bolts that hold the oil pan in place. In some cases, you may need to remove the left engine mount to get to all the bolts on the left side of the oil pan. Additionally, you will need to torque the bolts to specific values, and it can be difficult to get a torque wrench in all the required places.

Another challenge is dealing with oil leaks. If you are replacing the oil pan gasket, it is likely that you have an oil leak. This can be a messy and frustrating problem to fix, and it may require cleaning or replacing other parts of the engine. It is important to be very careful when working with oil and other fluids, as they can damage the engine and surrounding components if not handled properly.

The N55 oil pan gasket replacement process can also be time-consuming, especially for those who are not experienced with this type of work. It can take several hours to complete the job, and it may require some trial and error if you are not familiar with the process. It is important to have a good set of tools and a clear understanding of the steps involved before you begin.

Overall, N55 oil pan gasket replacement is a challenging DIY task that requires a good amount of experience, knowledge, and time. It is important to be prepared and to have a clear understanding of the process before attempting this job. For those who are not comfortable with wrenching or working on engines, it may be best to leave this task to a professional mechanic.

N55 oil pan assembly is available for purchase

The N55 oil pan assembly is available for purchase. This is good news for BMW owners who need to replace their oil pan gasket. The oil pan gasket is a common source of oil leaks in BMW N55 engines. The N55 oil pan assembly can be purchased online from retailers such as eBay and BimmerWorld.

When replacing the oil pan gasket, it is important to follow the correct procedure to avoid further damage to the engine. This may include removing the underbelly pans, disconnecting the coolant line on the sway bar, and lowering the subframe. It is also important to use the correct torque specifications when tightening the bolts on the oil pan.

In some cases, it may be necessary to modify the oil pan to fit the specific model of BMW. For example, the power steering pump may need to be modified or relocated to clear the oil pan. Additionally, the oil pan may need to be drilled or welded to accommodate the oil pump and suction pump.

The N55 oil pan assembly is a crucial component of the BMW N55 engine, and proper maintenance and repair are essential to ensure the engine's performance and longevity. It is always recommended to consult a qualified mechanic or BMW specialist when performing any repairs or modifications to your vehicle.

The availability of the N55 oil pan assembly online provides BMW owners with the option to purchase the part separately and perform the replacement themselves or with the help of a mechanic. This can be a more cost-effective alternative to taking the car to a dealer or specialist for repair.

S55 oil pan can be adapted to fit the N55

The S55 oil pan can be adapted to fit the N55 engine. This conversion was originally done by BMW on the M235i R, but it requires some modifications. The power steering pump mount on the original oil pan needs to be cut off and welded onto the S55 oil pan.

Step 1: Cut off the Power Steering Pump Mount

Cut off the corner of the original N55 oil pan where the power steering pump bolts are located. This will involve removing the three bolt holes that the power steering pump attaches to (two in the front and one on the side).

Step 2: Prepare the S55 Oil Pan

• Obtain a later aluminium version of the S55 oil pan.
• Modify the S55 oil pan by welding on the cut-off section from the original N55 oil pan. Ensure that the weld is strong and secure.
• Make any necessary adjustments to the S55 oil pan to clear the subframe and steering rack bolts. The S55 oil pan should sit slightly lower than the subframe but higher than the jacking point.

Step 3: Address the Side Bolt Hole

• Remove the side bolt hole on the S55 suction pump that interferes with the weld.
• Create a weld-on stud in its place to secure the suction pump.

Step 4: Modify the Power Steering Pump Bracket

• The recess for the power steering pump on the S55 oil pan may interfere with the suction pump. Modify this area to ensure clearance.
• Mill down the face of the power steering pump bracket by 7mm to create the necessary clearance.

Step 5: Assemble the Oil Pan

• Bolt the modified S55 oil pan to a spare N55 bed plate to keep everything located properly during welding.
• Cut out the front bearing cap from the bed plate to allow access for welding the inside of the oil pan.

Step 6: Finalize the Installation

• Obtain the following parts: S55 oil pump, suction pump, oil pick-up, oil pan bolts, oil pump bolt set, weld-on stud, sump gasket.
• If you have a single turbo, block off the rear port on the suction pump.
• Enlarge the hole in the chain guide and tensioner bracket to accommodate the larger snout on the S55 oil pump.
• Install the modified S55 oil pan and all associated components onto the N55 engine.

By performing these steps, you can successfully adapt the S55 oil pan to fit the N55 engine, providing the benefits of improved oil supply and better performance under hard longitudinal forces.

N55 oil pan retrofit for EWG RWD

The N55 engine is known for its oil starvation issues, particularly during heavy braking and right-hand turns, which can lead to spun rod bearings and costly engine repairs. While BMW has addressed this issue in later models, owners of early N55 engines are left with limited options. One solution is to retrofit an S55 oil pan, pump, suction pump, and suction pipe. This modification has been successfully performed on both PWG and EWG variants of the N55 engine.

To perform the retrofit, you will need the following parts:

• S55 oil pan (later aluminium version)
• S55 oil pump
• S55 suction pump
• S55 oil pick-up
• S55 oil pan bolts set
• S55 oil pump bolt set
• M10 stud
• Sump gasket

Additionally, you will need to block off the rear port on the suction pump if you have a single turbo setup. The hole in the chain guide and tensioner bracket will also need to be enlarged to accommodate the larger snout on the S55 oil pump. It is recommended to use an N/S55 bed plate as a template for welding and to ensure proper alignment of the oil pan.

This retrofit is a labour-intensive job, but it can provide peace of mind for those who wish to track their N55-powered vehicles without worrying about oil starvation.

Another possible solution to mitigate oil starvation is to overfill the oil by about 1 litre. This is a temporary workaround until one can afford the S55 pump and pan retrofit or as a stopgap until a full engine rebuild is performed.

It is worth noting that the N55 M2 and M235i R models from BMW feature a similar modification, utilising an S55 oil pan and pumps. However, these models do not require modifications to the power steering pump due to their use of electric assist power steering.

For those with an E92 335i N55 RWD, there were initial concerns about clearance between the S55 oil pan and the front subframe. However, these concerns were unfounded, and the retrofit can be performed without issues.

When considering any modifications or track use of your vehicle, it is always important to consult with a qualified mechanic and perform thorough research to ensure the safety and longevity of your vehicle.

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