How to Prevent Carbon Buildup in BMW Intake Valves

Your BMW, like any other vehicle, comes out the factory shiny and clean both inside and out. However, every time you hit the road, that perfect appearance begins to fade away. As you use your car more and more, not only will it begin to deteriorate from general wear and tear, but it will also start to get dirty. We’re not just talking about mud on your tyres here, either. It can get filthy on the inside, particularly with the buildup of carbon! This can have a massive impact on your car’s performance, so allow us to explain exactly how to prevent carbon from building up, specifically on your BMW’s intake valves.

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Close up of a black BMW grille

What Is Carbon Buildup?

Carbon is a naturally occurring by-product of the internal combustion process that takes place within every vehicle’s engine, BMWs included. Initially taking the form of a dusty soot, the carbon that deposits itself within your engine will eventually harden, making it much more difficult to clean off. It can affect multiple areas of your car’s internal workings, including cylinder walls, injector nozzles and, as the title of this post suggests, intake valves.

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Why Is My BMW’s Intake Manifold Full Of Carbon?

Bizarrely, you might find that your intake manifold is full of carbon if you drive a new model of BMW, whereas if you’re in an older car it could be less of a problem – although the issue might still exist. Older engines would spray the fuel into the intake manifold in a rather uncouth manner, but doing so would essentially use the fuel itself to clean off any carbon that was beginning to build up (though some may escape the cleanse and remain).

More modern engines utilise direct fuel injection technology which means that the fuel is literally injected straight into the engine’s chamber, increasing fuel efficiency. However, this means that the carbon that would usually be cleaned off by the fuel is now untouched and allowed to harden on the intake manifold.

Is Carbon Buildup In Intake Valves Common In BMWs?

This might initially sound somewhat contradictory to the previous paragraph, but while modern BMW engines seemed to really suffer from carbon deposits, their newest creations may have broken this curse and solved the problem.

From the mid-2000s to the mid-2010s, BMW used what was called an N54 engine, which was highly susceptible to carbon deposits in its intake valves. However, certain BMW drivers have claimed that their newer cars, which now use B58 engines, don’t seem to have this notorious problem.

Since many of those N54-built BMWs are still on the road, it’s fair to say that carbon buildup in the intake valves is still a common problem, but it looks like the German manufacturer might have cracked the code on how to stop it.

How Do You Clean A BMW Air Intake?

Cleaning hardened deposits of carbon from your BMW’s engine is done through a process that’s somewhat bizarrely called walnut blasting. On the surface, a ‘walnut blast’ sounds more like a fighting move you’d see in the latest superhero movie to hit cinemas than a technique for improving your vehicle’s performance. But, believe it or not, the reason it’s called this is incredibly straightforward – it’s quite literally what it says on the tin.

Walnut blasting really does involve using compressed air to blast crushed walnut shells into your air intake valves. The shells themselves are soft enough to not damage the engine itself while being abrasive enough to loosen the carbon from your engine. The standout advantage of this method is that it’s possible without having to take the engine apart!

So how is it done? Let us explain:

  • Prep your engine – Remove the intake manifold, close the blow-by channels between the cylinder head and cylinder head cover to prevent walnut shells from entering areas that they shouldn’t.
  • Clean as much as you can with other tools – Before using your precious walnuts, attempt to clean off as much carbon as possible using other tools that you have to hand, like brushes or chisels.
  • Commence blasting – Ensure that you use an extraction adapter to remove the displaced carbon and the walnut fragments, while you blast the inside and outside of the air intake.
  • Air blast – Once you’ve removed as much carbon as possible, you can use plain old air to blast any walnut parts into an area where the extractor can remove them.

Remember, if you don’t feel confident performing this practice yourself, you could always take your BMW into your trusted local garage.

Close up of BMW badge

How Much Does It Cost To Clean A BMW’s Intake Manifold?

Thankfully, the cost of paying a professional to clean your intake manifolds for you probably won’t break the bank. Some services are priced up at under £100, whereas more thorough cleaning jobs could ring up at just over that three-digit mark. Of course, different technicians will vary their prices, with some charging over the odds while others seem to offer a bargain price.

How Do You Prevent Carbon Buildup On Intake Valves In BMWs?

One of the easiest ways to prevent the buildup of carbon is to make use of fuel additives which will actively aim to cleanse your engine and the fuel you use of anything that could hinder your vehicle’s performance.

Another key method for reducing carbon buildup is to simply keep on top of your car maintenance and have the vehicle regularly serviced. Change your oil regularly and give the car a good run at high speed every now and then. After all, it’s common knowledge that leaving any vehicle sitting on your driveway for weeks or months on end will not have a good effect on the car.

If carbon buildup is the tip of the iceberg and your BMW is on the way out, get a quote from us here at Scrap Car Comparison and we will track down the best offers for your old, unwanted or broken-down car no matter where you are in the UK. With a network of ATFs that’s spread across 99% of the country, we can even offer free collection for every customer! Give us a call on 03333 44 99 50 or use our scrap car price calculator to find out how much your scrap BMW car is worth today!

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