Carbon build up in back of the valves

Wagon still under factory maintenance.

After free oil change and new f/r brakes and disks (neither indicated by iDrive...), I went to pick up car and SA said it was running rough, gave me a loaner for weekend. Told me today that there is "carbon build up in back of the valves " and BMW NA just authorized them to open the engine and physically clean them (vs injecting a cleaner?)

Does anyone know what causes this and how to prevent it in the future? (when I am paying for maintenance.) Car is driven mostly highway, I use Shell 93 octane gas.

Originally Posted by Phoenix1

Wagon still under factory maintenance.

After free oil change and new f/r brakes and disks (neither indicated by iDrive...), I went to pick up car and SA said it was running rough, gave me a loaner for weekend. Told me today that there is "carbon build up in back of the valves " and BMW NA just authorized them to open the engine and physically clean them (vs injecting a cleaner?)

Does anyone know what causes this and how to prevent it in the future? (when I am paying for maintenance.) Car is driven mostly highway, I use Shell 93 octane gas.

No prevention ala ole FI(fuel injection) engine, the N54 535i is DI (direct injection); no fuel goes/spray on top of the intake valve. Overtime it'd build up carbon there. Maybe, maybe long freeway drive may help a bit.


If all engine becomes DI, the oil company ought by-pass adding detergent to gasoline and pas the saving to us

Originally Posted by HPIA4v2

No prevention ala ole FI(fuel injection) engine, the N54 535i is DI (direct injection); no fuel goes/spray on top of the intake valve. Overtime it'd build up carbon there. Maybe, maybe long freeway drive may help a bit.


If all engine becomes DI, the oil company ought by-pass adding detergent to gasoline and pas the saving to us

Not much you can do about the carbon build up. I try to run my engine at high RPMs onces in a while when warm for a short amount of time (usually a minute or so) with hopes that it might clean up some of the carbon.

I assume that in the future they will introduce some fuel fogging system like the ol nitrous foggers to mist a bit of fuel in the upper intake to solve this o so common DI carbon build up issue. Every DI engine has this issue so there will be an industry fix

My car is having hesitation issues and the service guy is suggesting the same, but telling me BMW will not cover it under the warranty. Did you have to argue with them to get them to cover it?

I was waiting for this. Many 535 owners are in denial about carbon buildup in DI engines. This is the big "tune up" of the future.

i had a problem with "shuddering" at certain rpm's. i took it in and they told me i had the carbon build up problem. Walnut blasting the valves and intake ports and $550 later the cars runs better then ever. just a problem with DI motors like others have said.

Would running Chevron Techron Fuel System Cleaner, help?

Originally Posted by x54.4blue

Would running Chevron Techron Fuel System Cleaner, help?

No. Detergent in fuel only cleans the intake valve area if the car has port injection. It might still help keep the injectors clean but that is a different issue.

Originally Posted by Fahrer

No. Detergent in fuel only cleans the intake valve area if the car has port injection. It might still help keep the injectors clean but that is a different issue.

Chevron Techron Fuel System Cleaner is supposed to reduce carbon build-up. If you are building carbon isn't the carbon coming from the fuel and therefore additive in the fuel should work?

Originally Posted by x54.4blue

Chevron Techron Fuel System Cleaner is supposed to reduce carbon build-up. If you are building carbon isn't the carbon coming from the fuel and therefore additive in the fuel should work?

The carbon buildup is from oil vapors coming into the intake area from the positive crankcase ventilation system. These oil vapors are condensed/deposited on the intake area surface. With port injection the fuel ( with detergents) is constantly washing the deposits off the intake area surface, including the intake valves. With DI, the fuel is injected directly into the cylinder. Therefore, without any benefit of cleaning the intake area.

Can someone explain how this would not be covered under warranty? The car has 37K miles and is not operating to spec.

Originally Posted by bbal

My car is having hesitation issues and the service guy is suggesting the same, but telling me BMW will not cover it under the warranty. Did you have to argue with them to get them to cover it?

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They did the cleaning under warranty, but it had to be authorized by BMW regional service rep since this service would have been $500+. You need to push your dealer.

If you need me to scan and send the n/c report I can. Send me a private note with your email address.

Originally Posted by bbal

Can someone explain how this would not be covered under warranty? The car has 37K miles and is not operating to spec.

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My dealer called and got approval from the regional service advisor to do this under warranty.

There is NO reason that BMW in one area of the country is doing this under warranty, but not the others!

We need to rebel!!!

Service manager said there was NOTHING I could do to prevent this - it is a symptom of direct injection engines.

Thank you...I sent you a pm. I'll keep you all posted. I'm selling this car to a very good friend, but told him I won't complete the sale unless I'm sure the car is in perfect order.

Is it only problem with turbo engines?
Because 545 and 550 has valvetronic system that is closed to direct injection engines.

Originally Posted by phlfly

Is it only problem with turbo engines?
Because 545 and 550 has valvetronic system that is closed to direct injection engines.

It can be an issue with any direct injected engine. Any engines using intake port injection should be OK.

Originally Posted by x54.4blue

Chevron Techron Fuel System Cleaner is supposed to reduce carbon build-up. If you are building carbon isn't the carbon coming from the fuel and therefore additive in the fuel should work?

That only works on the injector. The carbon buildup is on the back of the valve and the stem. It being on the valve is not an issue, it being accumulated around the intake manifold leading to the valve intake is the issue as it restricts the airflow to the cylinder/chamber.

It can be done in about 2 hours uninterrupted if you DIY with a Dremel cable and a small wire brush with a good strong vacuum. Some people use solvent to soften the carbon but if you don't watch it you chance a accumulation of liquid in the liner and temporary hydrolock - solvent do evaporate after a period of time.

For Sh$% and giggles, son and I opened his N54 intake manifold to see what he has at 35K with a borescope - there is carbon buildup but nothing to worry about - yet. Some dealerships offer walnut shell blaster/cleaning for approx $500. I believe they do the intake manifold passages from the throttle valve downstream - (caveat) or so I am told. I may just do my own...

Nube

+1 - Techron does nothing to help this.

The Service Manager showed me the buildup he was cleaning in another 535. The valves closest to the front were cleanest and they got progressively dirtier with lots more carbon buildup as you went towards the rear - a big difference! So if your are checking yourself...

The carbon build-up is not isolated to DI's as everyone knows. Since the advent of EGR and various schemes to reduce harmful emission by burning them, the intake manifold had become dirtier as oil and other blow-bys are directed to the combustion chamber. I replaced my Pilot's timing belt, seals, water pump and tensioner last month; then decided to lift the intake manifold to retorque the heads - at 100K the manifold EGR passages were about 90% plugged up and the EGR valve was a mess. The 3 hour job became a whole day job just brushing and cleaning using copper bristle brush and lots of naphta. So it's all the engines... just a little faster with DI's. It's the nature of the beast and no one can get away from it short of elaborate misting design in the intake...

Originally Posted by Nube1kenobi

The carbon build-up is not isolated to DI's as everyone knows. Since the advent of EGR and various schemes to reduce harmful emission by burning them, the intake manifold had become dirtier as oil and other blow-bys are directed to the combustion chamber. I replaced my Pilot's timing belt, seals, water pump and tensioner last month; then decided to lift the intake manifold to retorque the heads - at 100K the manifold EGR passages were about 90% plugged up and the EGR valve was a mess. The 3 hour job became a whole day job just brushing and cleaning using copper bristle brush and lots of naphta. So it's all the engines... just a little faster with DI's. It's the nature of the beast and no one can get away from it short of elaborate misting design in the intake...

Your Pilot had 100K miles. I don't think one needs anywhere near that mileage to have such problems with a 535 or other DI engine. "just a little faster"? I doubt it. Detergent containing fuel must offer some benefit with port injected engines. A side note...premium fuel required by many engines often have higher detergent levels than regular fuel.

Believe it or not... fuel is not a factor here. Oil blow by is... the carbon contamination is relative to however efficient your cyclonic oil separator, labyrinth separators, or whatever other schemes manufacturers use to separate oil from the crankcase ventilation. Maybe we should start checking condition of our carbon canisters?

Originally Posted by Nube1kenobi

Believe it or not... fuel is not a factor here. Oil blow by is... the carbon contamination is relative to however efficient your cyclonic oil separator, labyrinth separators, or whatever other schemes manufacturers use to separate oil from the crankcase ventilation. Maybe we should start checking condition of our carbon canisters?

I believe the fuel can be a factor in that it "washes" the oily film before it can build up and carbonize on the intake area surfaces if the engine is port injected.

Originally Posted by Fahrer

I believe the fuel can be a factor in that it "washes" the oily film before it can build up and carbonize on the intake area surfaces if the engine is port injected.

Interesting link about this all:

http://www.autoobserver.com/2011/06/...-adopters.html

Originally Posted by Fahrer

I believe the fuel can be a factor in that it "washes" the oily film before it can build up and carbonize on the intake area surfaces if the engine is port injected.

That is the key... but even those engines are not immune to carbon build-up.