FAQ on Carbon Build-Up Issue (First Attempt) - Page 4

LLcoolM5 · 23rd August 2005, 03:51

Quote:

Originally Posted by Philip

What is the source of this information? If true, finding this difference in design may allow us to work backwards to understand how the problem is created.

All information for this FAQ comes from this site (M5board.com). Here is the quote from my original first attempt on the FAQ. " ...The information I obtain is directly from this M5board and I have no other sources of information. I was hoping we could contribute to factual data gathering".

The source of information you are refering about the head design comes from two threads: Carbon Build Up - How Common is it?
and
I am in big trouble with this one!

I myself keep having a intermetitment ODB code P0411 (Secondary Air Injection System Incorrect Flow Detected). I am hoping and praying it is not the dreaded C-word. This weekend I am going to take apart the secondary pump and start working backward from there. I have a very serious vested interest to try and narrow down the cause, source and remedy for the carbon build-up. This is no way me dictating or suggesting I know anything, I am just scanning the archives and gathering all the information into one source so as to spark idea and thoughts and maybe solve this problem.

mottati · 23rd August 2005, 06:35

i was at dinan last week for a couple of things, and they showed me a car getting cams, they pull out the engine, remove the heads, machine some clearance etc, etc.
I asked about this carbon issue. Jeff, at dinan mountain view, told me they have had a couple of customer cars with this. He went on to say that bmw has an 'elaborate repair kit' for this problem. The main 'fix' is drilling out the passages for the smog pump, in the heads, making the passages larger. THe carbon clogs the passages that the smog pump delivers air into, i believe near/at the exhaust port. He went on to say he thought the cars they had were babied, but it sounds like that may not be the main issue, it might be a passage that was too small by design, and easily clogs.
Mike

BKH · 23rd August 2005, 06:49

Quote:

Originally Posted by mottati

He went on to say that bmw has an 'elaborate repair kit' for this problem. The main 'fix' is drilling out the passages for the smog pump, in the heads, making the passages larger. THe carbon clogs the passages that the smog pump delivers air into, i believe near/at the exhaust port. He went on to say he thought the cars they had were babied, but it sounds like that may not be the main issue, it might be a passage that was too small by design, and easily clogs.

Now THAT starts to sound like a "design defect."

vndkshn · 23rd August 2005, 15:55

Quote:

Originally Posted by DavidS

Dan,

How about removing the exhaust and the top of the plenum and the intake runners, and spray a water/alcohol mixture onto one trottle butterflie at a time at perhaps 2k RPM?

David

Well, not sure what removing the exhaust really buys you, unless the concern is the alcohol damaging the cats, or the carbon clogging the cats.

The one concern with doing one at a time, the individual cylinders might dry up before you get the car in a driveable state to take it on its clean out run.

Definitely a task that not many would take on a whim... too bad engines don't typically warn before they grenade, it would be interesting to try it out on one!

vndkshn · 23rd August 2005, 16:03

Reading through the updated FAQ, two things strike me. First is the idea that only pre 01 cars had this issue. It has been reported that the 01s had higher oil consumption. I wonder if we are seeing this carbon problem on mainly older cars due to the oil consumption problem, or due to mileage/age. If due to oil consumption, the water trick likely will not work. I also doubt any fuel additives would have a great effect in this area. If due to "true" carbon buildup from the fuel, then either would help.

Second, I wouldn't associate the smog pump fix as true carbon build-up, but more of a sign of the high oil consumption.

wilsodh · 23rd August 2005, 16:18

Quote:

Originally Posted by mottati

The main 'fix' is drilling out the passages for the smog pump, in the heads, making the passages larger. THe carbon clogs the passages that the smog pump delivers air into, i believe near/at the exhaust port.....it might be a passage that was too small by design, and easily clogs.
Mike

Atheroclerosis is not an easy fix in humans either... ; o

Maybe we are getting somewhere... if we could get our hands on some BMW documentation which speaks to this, we might have a stronger case to make to get this fix covered under warranty. I can imagine that documentation pertaining to 'design flaws' (or perhaps 'design deficiencies') would not be disseminated lightly owing to warranty implications. Anybody have a well-placed friend who works at BMW??

Cheers,
Dave

E39 MFIVE · 23rd August 2005, 17:13

Well in regards with Water injection.

Its the miracle Mod for forced induction vehicles.

Not only does it instantaneously reduce intake temps to
close to ambient outside temps, greatly reduces chances
of detenation, and steam cleans the carbon build up.

more info at www.coolingmist.com and www.aquamist.com

But they are for forced induction, with super heated charged air
coming from the turbos, which evaporates the water, turning it
into steam which physically asorbs heat and cleans the engine.

Not sure how it could be done with normally aspirated engines.
it certainly would be worth a try..

DavidS · 23rd August 2005, 17:41

Quote:

Originally Posted by vndkshn

Well, not sure what removing the exhaust really buys you, unless the concern is the alcohol damaging the cats, or the carbon clogging the cats.

The one concern with doing one at a time, the individual cylinders might dry up before you get the car in a driveable state to take it on its clean out run.

The purpuse of removing the exhaust would be to spare the O2 sensors and the cats from the carbon flakes.

I don´t think the cylinders would be wet at all apart from a brief moment during each intake cycle.

I have another three ideas:

1. Shot blasting with tiny CO2 pellets through different nozzles sweeping the cylinder walls. Nozzle enters through the spark-plug hole, and through the the exhaust headers . The advantage over other kinds of shot blasting is that there is no clean-up necessary, the shot blast "sand" evaporates.

2. Thermal chock with liquid nitrogen. This would make the carbon deposits shrink more than the engine block, and fall from the cylinder walls.

3. Solvent pumped in through the spark-plug hole, with an outlet tube located at the top corner of the cylinder (so no air is trapped) and then going out through the spark plug hole too. Combined with intense ultrasound from a transmitter inside the cylinder.

David

BKH · 23rd August 2005, 19:32

Just an idle thought here - would one fail emissions testing with a smog pump-triggered SES light - and would it fall under the extended EPA emissions warranty?

vndkshn · 23rd August 2005, 22:11

Quote:

Originally Posted by DavidS

1. Shot blasting with tiny CO2 pellets through different nozzles sweeping the cylinder walls.

2. Thermal chock with liquid nitrogen.
3. Solvent pumped in through the spark-plug hole

Interesting ideas.. only issue, with number 1, whatever is used to inject the CO2 pellets would have to be very flexible. The deposits form on the piston head and the cylinder head, not the cylinder walls. Number 2 would require filling the whole cylinder, or somehow "squirting" it around in the cylinder. Wonder what effect that might have the the cylinder wall finish though... Number 3, my concern would be the solvent leaking past the rings and getting into the oil pan and basically removing any oil from the wrist pins as well as the main and rod bearings. Could be a rough initial startup.