AC Schnitzer
Well-Known Member
Greetings to all,
For anyone interested in washing your engine bay, here is a rough guide of how you can do so.
Disclaimer: As with all DIYs or write ups, I need to highlight that it is your responsibility to ensure that all parts in your engine bay, specifically your electrical wirings are in good condition.
By good condition, eg. bare electrical wirings are not exposed or torn rubber hoses.
With relatively later model cars from the late 90s onwards, you should be safe as car manufacturers do ensure that all parts under the engine bay are weather proof.
However it is still your responsibility to give the engine bay a good visual inspection to see if that is the case, in particular modded cars. eg. HIDs, Gruppe M porn, KNN intakes, so forth. Do what is necessary to cover your intakes with plastic bag.
Today is a stock M3 so it is relatively straight forward.
Step 1 - Before beginning, make sure your engine is cold. By definition of cold, it means your exhaust manifold is cold enough for you to touch with your bare hand.
Thereafter proceed to start your engine and let it idle for about 1 min. This is done so because the degreaser is able to break down dirt and grease a lot quicker.
Step 2 - There are aerosol and citrus type. I bought a few bottles at a time and hence decided to finish this last bottle. Do note Aerosol does produce odor. So please wash your engine bay when its windy.
Here are some areas where dirt have accumulated.
Step 3
Spray degreaser all over engine bay generously. Make sure you get the degreaser into confined areas of the engine bay.
Step 4
Let the degreaser break down the dirt and grease for about 1-2 minutes. If you notice some areas may require scrubbing, you can further agitate the dirt with some light scrubbing.
Step 5
Use low pressure hose to rise away the engine. Work with gravity start from the top followed by going to the bottom. If you start from top to bottom in 1 area, and start from the top again, you will find more dirt stuck between hoses etc.
Step 6
Once the above is done, once again start your engine and let the engine idle for about 2-3 minutes. This is to help heat evaporate water in confined areas which are not accessible by hand. You may want to close your bonnet to help contain the heat.
Notice most areas are now dirt free.
Step 7
Once engine is done idling for 2-3 minutes, use a towel or cloth of your choice to wipe it down.
Notice some areas where dirt used to accumulate are now gone.
Step 8 - All done !
Don't forget to remove any plastic bags that you have placed to aftermarket intakes.
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PS: For E9X M3 Owners, it may be a good idea to cover up your upper air intake.
If you are lazy, you can still proceed with the whole process without covering the air intake.
I took the liberty of removing the air intake cover. As you can see from the photos, there is a drainage at the bottom of the intake pipe for water to flow out safely.
This is the 2nd drainage for the water to flow out of the bumper intake. The air filter has no contact with the bottom of the airbox.
Any excessive amount of water will flow out through the 2nd air intake located at the bumper.
However, despite all that, please do not be a dickhead and happily flush huge amount of water into the air intake.
That is all.
For anyone interested in washing your engine bay, here is a rough guide of how you can do so.
Disclaimer: As with all DIYs or write ups, I need to highlight that it is your responsibility to ensure that all parts in your engine bay, specifically your electrical wirings are in good condition.
By good condition, eg. bare electrical wirings are not exposed or torn rubber hoses.
With relatively later model cars from the late 90s onwards, you should be safe as car manufacturers do ensure that all parts under the engine bay are weather proof.
However it is still your responsibility to give the engine bay a good visual inspection to see if that is the case, in particular modded cars. eg. HIDs, Gruppe M porn, KNN intakes, so forth. Do what is necessary to cover your intakes with plastic bag.
Today is a stock M3 so it is relatively straight forward.
Step 1 - Before beginning, make sure your engine is cold. By definition of cold, it means your exhaust manifold is cold enough for you to touch with your bare hand.
Thereafter proceed to start your engine and let it idle for about 1 min. This is done so because the degreaser is able to break down dirt and grease a lot quicker.
Step 2 - There are aerosol and citrus type. I bought a few bottles at a time and hence decided to finish this last bottle. Do note Aerosol does produce odor. So please wash your engine bay when its windy.
Here are some areas where dirt have accumulated.
Step 3
Spray degreaser all over engine bay generously. Make sure you get the degreaser into confined areas of the engine bay.
Step 4
Let the degreaser break down the dirt and grease for about 1-2 minutes. If you notice some areas may require scrubbing, you can further agitate the dirt with some light scrubbing.
Step 5
Use low pressure hose to rise away the engine. Work with gravity start from the top followed by going to the bottom. If you start from top to bottom in 1 area, and start from the top again, you will find more dirt stuck between hoses etc.
Step 6
Once the above is done, once again start your engine and let the engine idle for about 2-3 minutes. This is to help heat evaporate water in confined areas which are not accessible by hand. You may want to close your bonnet to help contain the heat.
Notice most areas are now dirt free.
Step 7
Once engine is done idling for 2-3 minutes, use a towel or cloth of your choice to wipe it down.
Notice some areas where dirt used to accumulate are now gone.
Step 8 - All done !
Don't forget to remove any plastic bags that you have placed to aftermarket intakes.
-------------------------------------------------------------------------------------------------------------------------------
PS: For E9X M3 Owners, it may be a good idea to cover up your upper air intake.
If you are lazy, you can still proceed with the whole process without covering the air intake.
I took the liberty of removing the air intake cover. As you can see from the photos, there is a drainage at the bottom of the intake pipe for water to flow out safely.
This is the 2nd drainage for the water to flow out of the bumper intake. The air filter has no contact with the bottom of the airbox.
Any excessive amount of water will flow out through the 2nd air intake located at the bumper.
However, despite all that, please do not be a dickhead and happily flush huge amount of water into the air intake.
That is all.
