Odd solution about carbon...

[brusk]

That's not true. There are two lines in PCV systems one going to the intake behind the throttle body and one in front of the throttle body. In this case one behind and the other before the turbo. When you floor it and the intake manifold is pressurized the engine will have higher crankcase gasses from the blow by passed the rings then gets sucked back in from the intake pipe before the turbo. This is where the catch can is placed.

[shah269]

Soooo to sum it up...oil+pressure+high temp= high speed drops carbonizing when they come in contact with the very hot head and valve.

[Freon]

Aenema, Brusk's explanation is correct. The PCV system (it's not just one valve) is not active just at idle and low load. At high load you vent to the intake pre-turbo, which will have a slight vacuum. High load is when you are going to have the most pressure build up in the crank.

I also don't buy that the turbo seals if in good condition are leaking. Once they start leaking the turbos should be replaced. There will be some oil in the turbo compressor due to the pre-turbo PCV vent.

[Ænema]

Originally Posted by Freon

I also don't buy that the turbo seals if in good condition are leaking. Once they start leaking the turbos should be replaced. There will be some oil in the turbo compressor due to the pre-turbo PCV vent.

The seals may not be leaking per se, but the stock MHIs use a piston seal, which at low loads/pressure don't seal as well as they could. That's why RB and VTT upgrade the seals to a step gap design to help with the oil consumption.

[mike the snake]

Is there a way the crankcase vent system could be routed outside the engine? Maybe through an oil catch can, and out to the atmosphere?

Seems like it could probably be easily be put back for smog tests.

Probably not the best for the environment, but it sure would cure the carbon buildup problem for good!

Not sure if it would even be that much worse than some of the methods offered for cleaning the carbon (aside from the walnut shell thang).

I worked at a shop that was not allowed to use water to clean things like wheels and parts, we had to use cans of brake cleaner and solvents and rags. There's no way that was better for the environment.

[Freon]

Yes, you could just run the crankcase vents straight from the block to atmosphere, but it will get oil everywhere in your engine bay. I would highly recommend against that.

For anything but a dedicated race car, a catch can is solution. If you want to get fancy, the colder the catch can is relative to the vented gases, the better condensation you will get.

Any drain off from spraying water on engine parts would have to be treated before allowed to enter a sewer system, septic system, or the ground. It's about protecting the water supply. Dump too much crap into the ground and every well in miles could be ruined. I'm not surprised in the least. Hobbiest oil-changers who dump their used oil down the sink is a big problem, and why you typically cannot install a floor drain in new garage constructions these days. I think it can be tough just to install a sink in a garage in some cities. Protip: any oil change shop will take your used oil for free and recycle it.

[tracer bullet]

Kerosene in the oil does clean things the oil contacts, this is true. I've gambled and cleaned out sticky lifters in previous cars this way. However, kerosene is not a good lubricant. I'd never do more than idle with it and even then not for a very long time. I'd never have it in for 100's of miles, especially driving with it and potentially higher revs. Asking for trouble.

And as a general rule you don't want any kind of cleaners whatsoever in your oil. You prevent that at all costs. For those that change their oil by pushing a tube down in from the filler at the top, do not clean that tube with anything afterwards.

I spent 10 years doing Quality Engineer and warranty analysis work at an engine manufacturing plant providing to Ford, and was once ICML certified in lubrication and oil analysis. I say that not to sound cool or to say that I'm necessarily even right, but just that I've been around a lot of this stuff for a long time and have seen a lot of damaged engines related to a lot of different things getting into the oil. Please don't put kerosene or any other cleaner into your oil unless you have a known problem in the oil system, realize that you are gambling when you do so, and definitely don't drive on it.

[AlBinVA]

and would like some indications of the problem. from what I read, it's not if you will get it, but when. I have 50k miles on my 135 and do not have any sluggishness or rough idling or any apparent (to me) engine noises or issues.

So, can anyone describe to me the telltale signs of carbon buildup or should I just assume that I have it and have it removed?

With regard, to additives added to the oil, JUST SAY NO.

[mike the snake]

My 135 with 44k miles ran normally, only when I went full throttle did it buck a couple times, and then went to misfiring and what I suspect is limp-mode, CEL and very little power with engine shaking. After a couple minutes, or after stopping and restarting, the engine went back to running fine.

It never gave any indications that the valves were gunked up, always idled and ran smoothly.

After the wlanut shell valve cleaning, no more misfires, and seemingly a bit more power.

3k miles later, and I just installed the Burger oil catch can, which should help.

I was also told that the oily mist in the blow-by that normally makes it's way into the engine affects the octane rating and reduces power.

[m7ammed]

Sorry to sound dumb, but one would think BMW would have installed an oil catch can if it would have helped with this? Is there any other reason why BMW never installed something like this?

[mike the snake]

BMW, Audi, Volkswagen, Minis, and others, all are having the same issues with carbon buildup. It has to do with the direct injection engines.

[shah269]

I hear that the VW guys with their DI engines are having major issues!
Not only are the cars drinking oil but the carbon build up is nuts!
Volvo is totally freaked out by it since all of their cars next year will be 2L TDI's (Turbo Direct Injection)

[Fed P]

It's funny to read that Volvo is freaked out - how do you know this? It seems they shoulda known what they are getting into, the problem has always been around since the beginning of DI!

[shah269]

well as always it started off with the words "How bad could it be!"
And ended with...."Oh really that bad!"
Remember volvo people hold on to their cars till they are dead! So think how bad the crbon build up on a 2L DI Turbo would be at 100+K miles!

[Qbrozen]

Originally Posted by m7ammed

Sorry to sound dumb, but one would think BMW would have installed an oil catch can if it would have helped with this? Is there any other reason why BMW never installed something like this?

Because it wouldn't look too good to the joe schmoe consumer that they have to add "empty catch can" to their required maintenance schedule.

[Pig Farmer]

For what it's worth, I installed a BMS catch can about a year ago. It gathers a couple tablespoons of oil between each oil change (~4'000 miles or 4 months). The last time I drained the catch can I noticed that the inside of the hose running to the BMS was coated with oil. The inside of the hose leaving the BMS was bone dry. So it would appear that the catch can is helping to some degree. I plan on dropping the intercooler during the next oil change to see if the intercooler is collecting any oil. Prior to the catch can, I did notice a small amount of oil would accumulate in the intercooler. And while the intercooler probably acts like a large catch can, oil in the intercooler reduces it efficiency.

[Sindarin]

Just out of curiosity, has anyone had any carbon issues on the N55?

Reason I ask is that the N55 had a number of improvements over the N54 to the crankcase ventilation system to help prevent carbon deposits.

[gdub]

mine was barely drivable, misfiring at idle and anything WOT above 3k it would misfire and then CEL. mainly cylinder 3, but cylinder 6 would show sometimes, and sometimes more than 1 or 2 cylinders would show error. this was at 37k, it's been blasted since and it runs great. i'll be getting a catch can soon

[yawn]

So I have the BMS OCC, but just how much does it stop the carbon buildup? I don't doubt for a second that it's not catching the bad stuff (I cleaned out a thin film after 6 months) but we still need to walnut blast every now and then right? It's no cure, or is it?

[Fed P]

Originally Posted by sharkatron

So I have the BMS OCC, but just how much does it stop the carbon buildup? I don't doubt for a second that it's not catching the bad stuff (I cleaned out a thin film after 6 months) but we still need to walnut blast every now and then right? It's no cure, or is it?

I have not seen a definitive answer on "how much" - only that it helps, as you yourself know since what you cleaned out did not end up on your intake valves. Carbon cleaning is still gonna be necessary =|

Lots of people see varying levels of oil in their catch cans, seems to depend on a lot of things, from type of driving to the particular car.

[shah269]

One of the things I use to do to help my old 1.8Ts (had to, Bug and Jeta) stay running happy even though all the other 1.8T's were spitting and crying was this.
Let the car warm up, depress the break as hard as you can and gunt he engine up to redline twice to three times once a week.
Funny thing would happen, the engine would run a little rough for a few seconds .... just a little cough or two and then she would run smooth as butter.

Before my last oil change from BMW jungle juice to the French Elf my mechanic uses I added a half a cup of chevron Techron to the oil. I’ve done this on the bikes to help clean the guts. Though in a bike is’ more like 1.4th of a cup. Worked very well on my very old VFR and my very abused GPZ. And did a number of times on the old 1.8T.

The more I think of this, the more we need to be 100% sure as to where this oil/carbon is coming from? Is it the crank case atmosphere? Is it blow back of some unburned fuel in the combustion chamber? Is it a simple issue of the ethanol that is being added to our gas?

Once a true root cause is determined then a true solution can be implemented. Till then boys, I’m sorry but we are just sticking out dicks into holes hoping we are in the right one.

[Colt]

Originally Posted by m7ammed

Sorry to sound dumb, but one would think BMW would have installed an oil catch can if it would have helped with this? Is there any other reason why BMW never installed something like this?

Cost.

Originally Posted by sharkatron

So I have the BMS OCC, but just how much does it stop the carbon buildup? I don't doubt for a second that it's not catching the bad stuff (I cleaned out a thin film after 6 months) but we still need to walnut blast every now and then right? It's no cure, or is it?

No it's not a cure, just a temporary solution to something that is inevitably going to happen one way or another.