# Houston (Munich) I think we have a problem



## Philm35 (Aug 19, 2010)

What are the symptoms of carbon buildup?


----------



## DC-IT (Sep 27, 2009)

Philm35 said:


> What are the symptoms of carbon buildup?


My D did not display any symptoms and it drove as normal with full turbo boost and no stutter/shudder or limp mode throughout the persistent SES!
The tech only discover carbon build up when they remove the cylinder head!
Others experienced loss of power and rough idle.

Sent from BimmerApp mobile app


----------



## sirbikes (Aug 17, 2012)

What is carbon buildup / carbon fouling? How does it occur? Why does it occur? Why would BMW diesels be more susceptible to it than other brands/models? What role does fuel quality play? Does a particular driving style help mitigate it?

So many questions...


----------



## Hoooper (Jun 17, 2013)

If you look into other models with direct injection, you can see this is most certainly not a BMW diesel specific issue. Some of the worst is on the Audi FSI, but also seen on Mazda direct injected engines, and also other BMW gas direct injected engines. It seems to be mostly agreed upon in the gas world that the carbon deposits are a result of a lack of detergents in gas sprayed onto the valves like you would have with non direct injected engines. Since direct injection only has the fuel sprayed into the cylinder there is no valve cleaning effect from the fuel.

My guess for why ours is so bad (in some cases) is that there is a combination of soot from the EGR and oil through the PCV building up not just on the valves but in the intake manifold and EGR. In many of these other cars it has been more or less decided that you either need to settle for cleaning the valves every 10-20k miles or buy a newer DI design that has supplemental fueling before the valves (toyota did this from the start from what I can tell). Many RS-4 owners have been doing a 10k mile valve cleaning since 2008. I suspect we need to do the same thing on these, maybe a cleaning or at least inspection every 20k miles is in order, its not hard to pull the manifold and see whether or not you need to get a cleaning yet. My real interest is in whether or not this will be properly dealt with in future models or if valve cleaning is going to become a maintenance item like changing your oil.


----------



## KeithS (Dec 30, 2001)

sirbikes said:


> What is carbon buildup / carbon fouling? How does it occur? Why does it occur? Why would BMW diesels be more susceptible to it than other brands/models? What role does fuel quality play? Does a particular driving style help mitigate it?
> 
> So many questions...


Search and read and you will find most of your answers.

1) It is where light residue of combustion/oils is heated and over time builds up as a solid black carbon like material in the intake manifold, EGR plumbing and intake ports on the heads. And our sophisticated diesels have 2 sets of intake ports to swirl the gas as it enters the combustion chamber, one being smaller than the other making more places to carbon up.

2) Happens to all direct injection engines gas or diesel (fuel injected directly into the cylinder instead of the intake). There is no fuel to wash the oils into the combustion chamber as with older systems that injected the fuel into the intake (only on gasoline engines).

3) It is not limited to BMW Diesels. Having to use heavy EGR to meet more recent pollution requirements in a Diesel is essentially putting soot into the intake system making this problem much worse. BMW is playing with the EGR system with the various updates to change the way it works to minimize the build-up. Some manufacturers are playing with intake valve timing to stop/minimize the "puff" of hydrocarbons that flows backwards from the combustion chamber into the intake when the intake valves open.

4) Not related to fuel. The theory is by driving the car hard from time to time, the high air flow will push these contaminates into the combustion chamber and avoid the build up. Again just a theory.

5) I expect this will never be totally eliminated, but am accepting as long as the cost to clean the carbon is reasonable.


----------



## 335dFan (Nov 8, 2012)

KeithS said:


> 4) Not related to fuel. The theory is by driving the car hard from time to time, the high air flow will push these contaminates into the combustion chamber and avoid the build up. Again just a theory.
> 
> 5) I expect this will never be totally eliminated, but am accepting as long as the cost to clean the carbon is reasonable.


I am a proponent of the drive fast for engine health method. Another excuse to flog the beast into submission. And then clean the rest every 40k or so. But I am only at 17k, so who knows what the future will bring.


----------



## Hoooper (Jun 17, 2013)

I would agree it shouldnt be cleaned more frequently than necessary. Considering it only takes about a 1/2 hour to pull the manifold, check, and put it all back, there is no real excuse to not checking at least every 10k miles (or oil change) unless you are just flat out mechanically incompetent. Everyone will have a different approach to the cleaning, I am more likely to try to lightly clean every 10k and not let a tough layer form than to really get after it every 40k. Really depends on how quickly it forms and it seems like driving habits can have a lot to do with that


----------



## KeithS (Dec 30, 2001)

Every 10K is a bit too frequent for me. If I have to clean once in 150K miles (typical time I keep a car), I'm OK with that. Yes the intake is easy to clean, it's the head I'm worried about. I have had conflicting stories that the head can or can not be cleaned in place. Pulling the head is a real big deal. As I indicated there are 2 intake paths. The main large one with the swirl flaps (swirl port), but there is also a secondary (tangential port). I think it may be hard to clean the tangential port in the intake manifold because it's smaller, is less direct/straight, and can plug off completely. I'm sure to be continued......


----------



## montr (Oct 7, 2006)

Hoooper said:


> I would agree it shouldnt be cleaned more frequently than necessary. Considering it only takes about a 1/2 hour to pull the manifold, check, and put it all back, there is no real excuse to not checking at least every 10k miles (or oil change) unless you are just flat out mechanically incompetent. Everyone will have a different approach to the cleaning, I am more likely to try to lightly clean every 10k and not let a tough layer form than to really get after it every 40k. Really depends on how quickly it forms and it seems like driving habits can have a lot to do with that


Is it really only 1/2 hour? Has anyone here has removed the intake manifold to check for deposits?
Thanks


----------



## Hoooper (Jun 17, 2013)

montr said:


> Is it really only 1/2 hour? Has anyone here has removed the intake manifold to check for deposits?
> Thanks


Yeah, maybe not a half hour. If you get some practice it might be somewhere around 30-45 minutes. I did it tonight in 3 hours my first time to take it apart, clean a bit, and put back together. Probably about an hour for each direction of remove/install. 30 minutes of that is time wasted screwing around with the second engine cover at the rear of the engine. Here are some pictures of how nasty the insides of these manifolds are. Seeing this, I think I might have to take back my thoughts that the manifold could easily be cleaned. It could probably be cleaned with a good long soaking but even that is questionable. We do have a bit of a better situation than some of the other carbon buildup issues around since this is more like a gunk/slime than the hardened carbon on other DI engines. Im starting to think that the idea of running some meth to cut down on gunk isnt such a bad idea.

I dont believe anyone who says they dont have buildup. Unless you can prevent oil mist from the PCV from entering the manifold or prevent the EGR from operating you will be getting buildup. My take on this just from the look of this gunk, along with where it all starts is that oil mist in the intake flow mixes with soot from the EGR and forms a sort of sludge. The sludge gets stuck on the walls of the intake and all of a sudden weve got a buildup issue.

EGR valve, not terrible.









The neck of the manifold









View inside the manifold









I expect this is the swirl valve port









Intake port. This amount was pretty much the typical amount. It varied from basically just a slime to up to 1mm thick









The pile of junk to the right of the EGR here is about how much I took out of the EGR alone









This is how much I scraped out of the intake just from about the first 1/2" inside the neck. Im not sure I even want to know how much would come out of the entire manifold.


----------



## KeithS (Dec 30, 2001)

Hoooper said:


> Seeing this, I think I might have to take back my thoughts that the manifold could easily be cleaned. It could probably be cleaned with a good long soaking but even that is questionable. ....


The intake being plastic does limit your options. For example cannot use the ******* torch and air gun method of cleaning as has been done on the TDI intake (metal).

The dealer uses a walnut shell blasting process....


----------



## F32Fleet (Jul 14, 2010)

Glad to see that the build up was minimal. Everything looks normal.


----------



## Axel61 (Mar 10, 2011)

this what I wrote in another forum maybe will shed some light as to build up :

_what comes to mind is that gassers have somewhat the same issues now dont bang me on this a migos but I had a modded 02 MCS with you know WHO Flash LOL, anyway I drove the ****** for 128k and never had to do the crud in the intake is it because I drove the FALKER like a bat out of hell? well i ran into the guy I sold the car and he has put another 50k into the car mind you he took the flash OUT!! and put the OEM pully I beleive was at 15% and then he began to have problems, but, I know this guy ran the car like a bat out of hell also, but he took the essential parts i had put in and then he had to have his crud removed from the intakes. So Im LEANING to believe that those of us who have either JBD or RENNtech or whomever will MAYBE not have these issues. But, making a comparo with my past car with NOW 175k compared to my 30K DIESEL which has been in the shop for NOX EGR whatever the FALK else Ive been into its suffice to say MAYBE or MAYBE not will encounter the dreaded DDE Injector issues!!!_


----------



## Hoooper (Jun 17, 2013)

BMWTurboDzl said:


> Glad to see that the build up was minimal. Everything looks normal.


I hate that what is there is "normal" but youre right.



Axel61 said:


> this what I wrote in another forum maybe will shed some light as to build up :
> 
> _what comes to mind is that gassers have somewhat the same issues now dont bang me on this a migos but I had a modded 02 MCS with you know WHO Flash LOL, anyway I drove the ****** for 128k and never had to do the crud in the intake is it because I drove the FALKER like a bat out of hell? well i ran into the guy I sold the car and he has put another 50k into the car mind you he took the flash OUT!! and put the OEM pully I beleive was at 15% and then he began to have problems, but, I know this guy ran the car like a bat out of hell also, but he took the essential parts i had put in and then he had to have his crud removed from the intakes. So Im LEANING to believe that those of us who have either JBD or RENNtech or whomever will MAYBE not have these issues. But, making a comparo with my past car with NOW 175k compared to my 30K DIESEL which has been in the shop for NOX EGR whatever the FALK else Ive been into its suffice to say MAYBE or MAYBE not will encounter the dreaded DDE Injector issues!!!_


did you or have you ever checked for buildup by pulling the manifold on your D? I really dont expect that driving hard is going to keep oil/soot mix from sticking to the manifold so I would love for someone that drives it hard and has no buildup issues to pull the manifold so that we can all see what is really going on in there. If its clean, great. If not, we can put that myth to bed. I can believe that driving it hard MAYBE extends the time before cleaning but I just dont believe it prevents anything. FWIW mine obviously has buildup but I dont notice any lack of power, dont have any codes, or any other driveability issues...yet. If I were to buy this car again (which I would since buildup is just a fact of life with the newest generation of engines) the first thing I would do is go out and get an EGR delete done. Then installing a PCV catch can would be next and I bet the buildup issues would be gone


----------



## Axel61 (Mar 10, 2011)

Hooper reread my thread I stated that I had a FLASH and PULLY upgrades and car NEVER had any build up on my 02 MCS and I sold it at 128k the new owner had issues at arounf 175k!!!! w/o the installs i made, you make a judgement on this, it is confirmed by others and myself that this issue can be deferred by our style of driving but we also can be caught up with it, and NO!! I havent taken parts out to find out. i can say I MIGHT of had an issue back in December before the 1/2 mile my car went on LIMP MODE cause I had not used the cetane Booster and Injector cleaner for a month and then when we ran twice the car at 150 mph the car was so loose that even my girlfriend noticed it and ever since that i have had better mileage on my car, so we can ASSUME that these runs helped clean up ANY soot in my system!!


----------



## Hoooper (Jun 17, 2013)

Axel61 said:


> Hooper reread my thread I stated that I had a FLASH and PULLY upgrades and car NEVER had any build up on my 02 MCS and I sold it at 128k the new owner had issues at arounf 175k!!!! w/o the installs i made, you make a judgement on this, it is confirmed by others and myself that this issue can be deferred by our style of driving but we also can be caught up with it, and NO!! I havent taken parts out to find out. i can say I MIGHT of had an issue back in December before the 1/2 mile my car went on LIMP MODE cause I had not used the cetane Booster and Injector cleaner for a month and then when we ran twice the car at 150 mph the car was so loose that even my girlfriend noticed it and ever since that i have had better mileage on my car, so we can ASSUME that these runs helped clean up ANY soot in my system!!


I could have said the same thing before I looked because it didnt show any signs of buildup and THAT is the reason I said I would love for someone who drives hard a lot to actually pull the manifold so that we can see if there is a difference. If there is, that is *fantastic* and I will be blasting away at 150 into the future, but I am one for solid evidence and it doesnt pass the sniff test to me that driving it hard would prevent buildup since there is no real reason I can think of that it would.


----------



## Axel61 (Mar 10, 2011)

Also Hooper I agree w u on the catch Can which I forgot to mention I had on my 02 MCS(thanks for bringing this up!! amigo) I saw a catch can for a 335i and heres some info on it:

http://www.1addicts.com/forums/showthread.php?t=359427

http://www.e90post.com/forums/showthread.php?t=769963

http://www.bimmerfest.com/forums/showthread.php?p=7100218


----------



## Hoooper (Jun 17, 2013)

yeah, I think either EGR delete or a good catch can would both help a lot, since with just EGR delete at least you wouldnt really get buildup in the manifold (ive had enough other cars that keep puddles of oil in the manifold without gumming up) and with just catch can the soot should just shoot through the system since its dry. I really think that the oil mist combining with soot at the EGR is the entire source of the problem. Once that soot and oil binds together it would become thick, somewhat sticky, and heavy so it falls out of the airstream and sticks to anything it touches. Its all speculation, but in my opinion doing just one of those things should make a huge difference in buildup


----------



## Hoooper (Jun 17, 2013)

along those lines, I am going to set my CANtool to automatically delete emissions codes today and disable the EGR. I likely wont leave it that way for too long for the sake of the DPF since its still working, but I am interested to see if the autodelete will work on the EGR code(s) and if there will be any negative impact on performance.


----------



## TDIwyse (Sep 17, 2010)

I'm behind on my reading and playing "catch up"...

Hooper, THANKS for taking the time and sharing the info on the intake.

Question, is there a gasket that needs to be replaced, or is it reusable, when you remove the intake and replace? realoem shows 2 things called profile-gasket ... didn't know if it/they were reusable or not? http://www.realoem.com/bmw/showparts.do?model=PN73&mospid=51054&btnr=11_3876&hg=11&fg=40

And do you have the specs on the torque for the bolts when re-tightening? Did you use any thread sealant?

I had a cheap little boroscope I bought to look into the intake but couldn't reach the valves. The intake had a thin layer of the material you describe, but it wasn't "closing in" like my old VW TDI suffered from. The D has lots of air flow capability yet, enough to do 12.6's in the quarter mile anyway.

Could you see the valves when you had the intake off? Any pics of those? That's the part I'd be more concerned about...

Thanks again for sharing this info.


----------

