535i Carbon Build-up

My wife has an '08 535i that is used mainly in suburban driving - speeds from 35 to 55 mph, 6 to 10 miles a trip 3 days a week. How concerned should I be about carbon builp-up and if it happens, can it be removed without removing the head. The car has about 39,000 mile on it and has been serviced by the dealer since day one.

Hard to predict without physical inspection. I only use 93 Octane Tier One gasoline and run 20 ozs. of the BMW Fuel System Cleaner 82 14 0 413 341 every 3-5000 miles.

I have been told by a few sources that its not an issue with your car... Its a huge issue in the 8 cylinders... like my 545i. And as for the process of removing the buildup, on the 8 cyl the heads have to be removed. Not sure about your car.

You are probably going to have it at some stage in time. My car gets used for an 8-10 mile each way round trip commute 3-4 days a week, a 35 mile each way round trip 1-2 times a week and errand running. I had to have the carbon build up done around 49,000 miles. It was so bad that one of my intake valves was full of carbon.

Thinking back to my muscle car days, the big block engines used to run cold plugs, and carbon could build up if one did a lot of city driving. Some folks would switch to a hotter plug, lose performance, but the plugs would run cleaner. Now the engines are so much more sophisticated, I'm sure that this is no longer an option.
Since my daily trips are exceedingly short, every two or three weeks I take a trip to the Interstate and run the car 75 ish for a few minutes. I'm not sure this can help carbon build up, but I do enjoy being able to put my foot into it.

[QUOTE=Jaycal3;7208912]I have been told by a few sources that its not an issue with your car... Its a huge issue in the 8 cylinders... like my 545i. And as for the process of removing the buildup, on the 8 cyl the heads have to be removed. Not sure about your car.[/QUNOTE]

I think you might have it backwards...its definitely an issue on the x35 cars as well as most DI cars. The V8s possibly suffer from carbon buildup in the intake, but its not a major issue at all.
To the OP, the carbon can be cleaned with the heads on the vehicle...you'll just have to turn the engine so that the intake valves are closed. Some guys use something like brake cleaner or some other combustible liquid poured into the intake port to test if its fully closed.
Neither fuel cleaners nor driving style will keep the buildup from occurring....it will happen regardless...

Originally Posted by Mac Hadley

Thinking back to my muscle car days, the big block engines used to run cold plugs, and carbon could build up if one did a lot of city driving. Some folks would switch to a hotter plug, lose performance, but the plugs would run cleaner. Now the engines are so much more sophisticated, I'm sure that this is no longer an option.
Since my daily trips are exceedingly short, every two or three weeks I take a trip to the Interstate and run the car 75 ish for a few minutes. I'm not sure this can help carbon build up, but I do enjoy being able to put my foot into it.

Well when my wife drive the car on her 35 mile each way commute she is running at above 75 once she hits US 50.

Originally Posted by jim165

Neither fuel cleaners nor driving style will keep the buildup from occurring....it will happen regardless...

Agreed. And yes it will happen to your 535.

It's an issue as you have a direct injection engine. Sometimes BMW will clean the valves for you under warranty. I would say every 40k miles is a good interval.
I did both of mine and they were quite caked up. Afterwards they had much better throttle response and more power.

If you have to pay out of pocket then find an indie who has the walnut blasting equipment. Should run around $400 including new gasket.
You can do it now or wait a year, but you are within the range.