How do I know if I need to replace my BMW E30 E36 or E46 fuel door spring hinge?

If your fuel door is floppy or no longer “snaps” shut, your fuel door spring hinge is likely worn out. The good thing is the replacement takes minimal effort and the fuel door spring hinge OEM BMW replacement part is relatively inexpensive.

What is the OEM BMW spring hinge part number?

OEM BMW part number: 51171888374

What tools are needed?

The only tool needed to perform the fuel door spring hinge replacement is a needle nose pliers.

How long does the procedure take?

Approximately 3 minutes.

Where can I buy the fuel door hinge replacment part?

You can buy them from our store HERE. This is a brand new, Genuine OEM BMW spring hinge. Make sure to check out our other OEM BMW parts available.

What is the spring hinge replacement procedure?

Remove the old spring by taking a needle nose pliers and grabbing the hinge in the middle just below the center tab. Push inwards towards the car to disconnect the hinge from the center point until the hinge is loose. This allows the hinge to drop down and become disconnected from the top pivot point. Finally, completely remove the old hinge by pulling it out of the lower hinge pivot point. Scroll down for helpful images.

Install the new spring in the reverse order. Make sure the long, straight end is towards the bottom. First, slide the new spring into the lower hole and then the upper end of the spring into the upper hole. Hold the spring in place with one hand and grab the middle of the spring with a needle nose pliers just below the center tab. Push firmly inwards with the pliers until the spring flexes and catches on the center tab. Installation is complete. Scroll down for helpful images.

Where can I learn more BMW tips?

Learn more BMW pro tips by clicking HERE

What is a fuel octane rating?

A rating of fuel which measures its resistance to pre-detonate (create engine knock). The higher the octane number the more resistance the fuel is to creating pre-detonation. Or in other terms, the fuel octane rating is a way to control the burn of the fuel for different engine compressions to prevent uncontrolled detonation.

What is pre-detonation / engine knock?

On a typical 4 stroke engine cycle, during the compression stroke, the piston is moving up, compressing the air and fuel mixture. Just before the piston reaches the top of the compression stroke the spark plug will ignite the air-fuel mixture, creating an explosion which then pushes the piston downwards. This is driving force downwards is the power stroke which creates power. This power turns the crank and through the driveline will be sent to your vehicle's wheels.

Pre-detonation or engine knock occurs when the piston is compressing the air/fuel mixture and the temperature gets so hot the air/fuel mixture pre detonates on its own before the spark plug fires. This creates an audible noise called engine knock.

On a side note, this is how diesel engines work and why they are so noisy. Diesel engines do not use spark plugs to ignite the air-fuel mixture but rather use the high compression of the motor to detonate the air/fuel mixture.

When is engine knock more prone to happen?

Engine knock is more typical of higher compression motors (typical ratios of 10:1 or higher). These are motors which simply take the volume of the cylinder (when the piston is all the way down) and compresses it to a substantially smaller volume when the piston reaches the top of the cylinder head. An engine ratio of 10:1 will take a cylinder volume of .5 liters, for example, and compress it to one-tenth the size, .05 liters. This is a basic explanation of a high compression engine. BMW’s typically have high compression motors.

Where can I find which fuel octane rating my BMW needs to operate properly?

The easiest way is to look inside the fuel door for the minimum octane rating recommended by BMW. As stated above, you can run a higher octane fuel but there will be no benefit. If a gas station is out of the minimum rating you need simply just go to the higher octane fuel with no issue. See the below picture for an example of the location of this rating sticker. If this sticker is missing, you can refer to your owner’s manual to find the recommended octane rating.

Will running a higher fuel octane rating than BMW recommends result in performance gains?

No, you will get zero benefits of using a higher fuel octane rating than your engine calls out for. You are paying for more expensive gasoline that offers no upside to the performance of your vehicle. It is simply a waste of money. However, there will be no downside as it will not harm your engine.

Will it hurt my engine if I use a lower octane rating than what BMW recommends?

Yes, if your engine calls out for the use of 91 octane and you run 87, the fuel is at risk of pre-detonating causing damage to your engine. Please, follow the fuel octane ratings for which your engine was designed to ensure proper performance and longevity of your vehicle.

Where can I learn more BMW fun facts?

Learn more BMW fun facts by clicking HERE

BMW fuel cap holder:

When filling up your BMW with fuel, often times owners will remove the cap and let it hang down onto the body of the vehicle from the plastic lanyard. Some vehicles lack the plastic lanyard to begin with, tempting owners to place the cap on the trunk or roof while refueling. Either scenario will eventually cause scratches to your clear coat over time.

Luckily, BMW has a built in solution to the inside of the fuel door. The engineers at BMW had enough foresight to design fuel cap holder that sits on the inside door of every BWM model. This prevents any confusion on what to do with the cap when refueling.  Although the design has varied slightly over the years the function is the same. Simply place the fuel cap in the dedicated holder when fueling. 

Not only does this prevent scratches to the surface of your car, it also forces you to put the fuel cap back on before shutting the door. This may not be an earth-shattering tip but we observe the abuse of the fuel cap quite often when at the fueling station and feel it is worthy of a post to inform BMW owners of the little features the car has in place to make your life easier.

The below pictures show the E30 in white, E36 in yellow and E46 in silver.

Further reading on BMW Pro Tips.

Click HERE to learn more interesting BMW Prot Tips.