Carbon buildup Synopsis Cause and Solution (long post)

Tomnavigator · 03-05-2016, 01:33 PM

Here is a synopsis of the cause to carbon buildup in the intake of diesel vehicles and the possible solutions. This synopsis is based on known and accepted facts.
Facts:
1) Carbon buildup is a combination of oil and soot.
2) The main source of oil is from the positive crank case ventilation (PCV) with possible contribution from turbo oil seal leakage.
3) The main source of soot is from Exhaust Gas Recirculation (EGR)
4) EGR on the 335d is a high pressure EGR. This means that the exhaust is recirculated prior to the particulate filter that removes the soot.
5) EGR on the 335D is active under almost all engine loading conditions
6) Diesel engines generally don’t create soot under light loads.
7) Diesel engines generate significant amounts of soot under moderately high loading (heavy acceleration)
Conclusion:
First I will give you the background and cause of the source of our oil and soot. Oil mist is generated by high pressure combustion gasses that get around the piston rings. This is called blowby gasses. The blowby gasses pick up oil mist in the engine and must be vented to prevent excess pressure building up in the engine. The gasses are vented at the top of the engine in the valve cover of almost all engines. These gasses were vented to the atmosphere for the first 50 years of the automobile until the government realized that millions of cars on the roads venting oil created a lot of oil in the environment. The idea of venting the PCV to the intake came about in the 1950’s. This was not a problem because oil only in the intake does not create a buildup especially since the gasoline added to the intake from the carburetor washed out the oil. The problem was created when you removed the solvent (gasoline) and added soot (EGR). That is why direct injection gasoline cars now have carbon buildup now also. Diesel engines have more of a problem with carbon buildup because diesel engines create more soot especially when the engine is under a load like heavy acceleration.
Diesel engines create much more soot than gasoline engines. This is why modern diesel engines now have particulate filters to remove the soot from the exhaust. Anyone that has owned a pre 2009 diesel vehicle know that the harder you accelerate the more soot you produce. Moderately hard acceleration creates a light black cloud behind you. Hard acceleration creates a dark black cloud of exhaust behind you. Just watched trucks with diesel engines take off and you know that when a diesel accelerates under load that soot is formed. Light acceleration no soot. Moderate acceleration moderate soot. Heavy acceleration heavy soot.
Carbon bulid up is formed when oil and soot mixed together form a thick paste that collect in the intake and hardens when heated by engine temperatures. If you remove either component, the problem goes away. Remove all the oil and the soot is a dry powder that won’t stick and gets sucked into the cylinders and is burnt. If you remove the soot, the oil creates a film layer in the intake and the problem is eliminated.
Removing oil from the intake will be discussed first because it is easier to accomplish. Removing the oil from the intake is accomplished one of two ways.
The first way to remove oil from the intake is to remove the oil out of the PCV gasses with a catch can or a coalescing filter such as a provent 200. A catch can works by providing a wide spot in the line that allows the larger oil droplets to settle out. This removes the largest droplets only. A coalescing filter works using two methods of oil removal. The gasses enter the filter on a Tangential inlet. This tangential inlet causes the gasses to spin acting like a centrifuge to remove the oil droplets. The gasses then move toward the center where a coalescing filter is located. A coalescing filter is a filter that is designed to remove very small liquid droplets that won’t settle out of the air on their own because they are so small. Think of fog which is small water droplets in the air on a cool morning. The oil droplets collecting on the coalescing filter combine with other oil droplets and eventually get large enough to drip off the filter media. A Coalescing filter is much more effective that a catch can. The disadvantage of either of these methods of oil removal is that neither removes 100 percent of the oil. The removal efficiency of the catch can will be related to the length of the line from the valve cover to the catch can because oil will settle out in the line. The Coalescing filter will remove over 90 percent of the oil to probably 95 percent of all oil.
The second way to remove the oil from the intake is to actually remove the PCV gasses entirely from the intake. This is done by venting the PCV to the atmosphere. This removes 100 percent of the oil. There are two disadvantages of this method of oil removal. The first is obvious. You are venting oil mist into the air. The second disadvantage is that your car will set a Service Engine Soon (SES) light because you will disconnect the PCV line heater which is built into the plastic line that goes from the valve cover to the intake. A jumper must be placed in the line to eliminate the SES.
Removal of the soot is accomplished in three ways. First you can drive the car like a little old lady and minimize your rate of acceleration. This will probably not totally eliminate carbon buildup. But, may hopefully extend the life of the vehicle to 200,000 miles or longer before carbon build up occurs. Only time will tell how effective this method is at eliminating carbon buildup. The advantage of this method is that your fuel mileage will be excellent. The disadvantage is the loss of fun factor by not driving it like a BMW. Second method of elimination of soot is by eliminating the EGR. You can disconnect the motor that opens the EGR valve or block off your EGR. Either method is totally effective and cheap to do. To block of the EGR, just insert a disk in the line that blocks the EGR flow or. The problem with either disconnecting the EGR valve motor or blocking the EGR is that either method generates a SES light and won’t pass emissions inspection. The third way to eliminate the EGR is reprogramming the engine control module to eliminate the EGR. This method is not available stand alone and is expensive because it on only provided as part of a performance coding package. If done right coding out the ERG will not generate a SES but would fail an emissions test that monitors nitrous oxides.
What I am planning on doing. 1) I drive it like a little old lady until I eliminate PCV and EGR. I get 40 to 41 MPF on each tank of fuel (using the cars trip computer) on my 72 mile one way commute on 2 lane highway. 2) I will eliminate PCV by venting my crankcase gases to atmosphere through a Provent 200 coalescing filter to remove the oil prior to venting. I will put an oil collection container on the oil discharge port of the provent to collect the oil and dump the container at oil changes. The provent is not required. But, is my concession to protect the environment and only costs about $90 on ebay. 3) I may also unplug my EGR valve and put up with the SES while I wait for someone to offer affordable ERG elimination coding.

Editorial note: One day someone will realize that a lot of money can be made by offering an ERG elimination coding cheaply going for volume selling instead of trying to make a killing on one sale. Many people would pay $99 to for coding to eliminate EGR that will not pay $600 to $1,000 for stage one performance coding. Instead they make nothing hoping to make $1,000.
There is another way to eliminate carbon buildup. The installation of a solvent injection system in the intake. This works by the continuous injection of a solvent in the intake to clean the intake. The most common solvent injection system is a methanol/water injection system. This method of carbon buildup control will work if injected at a sufficient rate. However, due to purchase costs, operating costs, lack of information about needed injection rates and effects on engine life this method of carbon buildup control is not discussed here.

Yozh · 03-05-2016, 02:05 PM

Couple of points.

Meth is effective in our diesels and there is plenty of information in relevant threads on how to set it up properly.

Just disconnecting EGR or coding it our has had cases of cracked EGR coolers in Europe. That leads to coolant leaking into the intake and one case of hydrolocked engine. This is a reason everyone on this forum has had exhaust manifold side of the EGR cooler blocked as well. There is a proper kit available to block both sides of the EGR cooler, the exhaust and the intake side.

And as far as I know, JR does offer a tune that keeps all your emissions intact and codes out the EGR with it's corresponding SES light. It's a performance tune though and as such is not a $99 dream one wishes for. EGR still has to be physically blocked for the reasons mentioned above.

And one more. If you want the best "catch can", this is it:

defender_500_pd_leaflet_efu00126en.pdf

335D Alpha Pappa · 03-05-2016, 03:00 PM

2) The main source of oil is from the positive crank case ventilation (PCV) with possible contribution from turbo oil seal leakage.

So how does the oily vapors from the crankcase get to the intake? Where is the feedback loop?

gavronm · 03-05-2016, 03:15 PM

Not a bad summary. I second the idea that an inexpensive EGR delete "tune" would be an exptremely popular product. I would buy it.

Hoooper · 03-05-2016, 04:05 PM

Quote:

Originally Posted by 335D Alpha Pappa

2) The main source of oil is from the positive crank case ventilation (PCV) with possible contribution from turbo oil seal leakage.

So how does the oily vapors from the crankcase get to the intake? Where is the feedback loop?

The CCV connects into the intake at the elbow coming from the filter box/MAF tube just before the intake connects to the turbo(s)

Monroe · 05-16-2016, 03:47 PM

Monroe (me) has been building up oily carbon for more than a year. It began when the
dealer overfilled the crankcase. Evidenced suggested overfilled by only one quart.
Wrong. Months later I measured the overfill at several quarts and suspected from
evidence the oil was intended for gasoline engines. Additionally an unknown amount
of crankcase additive containing volatile xylene, toluene and another aromatic had
by the measuring day, evaporated; meaning considerable crankcase overfill.
I bought lunch for a self-employed PhD chemist, who suggested "things will get
worse." They have. Please accept my advice about dealer oil changes:
Before you retrieve your car, cut a plummers' snake to match the dip stick.
Don't drive away until you are convinced the crankcase is not overfllled.

kydiesel35 · 05-16-2016, 04:26 PM

Quote:

Originally Posted by Yozh

Couple of points.

Meth is effective in our diesels and there is plenty of information in relevant threads on how to set it up properly.

Just disconnecting EGR or coding it our has had cases of cracked EGR coolers in Europe. That leads to coolant leaking into the intake and one case of hydrolocked engine. This is a reason everyone on this forum has had exhaust manifold side of the EGR cooler blocked as well. There is a proper kit available to block both sides of the EGR cooler, the exhaust and the intake side.

And as far as I know, JR does offer a tune that keeps all your emissions intact and codes out the EGR with it's corresponding SES light. It's a performance tune though and as such is not a $99 dream one wishes for. EGR still has to be physically blocked for the reasons mentioned above.

And one more. If you want the best "catch can", this is it:

Attachment 1376607

Whoa. Now that's a nice catch can, wonder how much that costs.

My intake manifold looked a little on the oily side today, no carbon. Been spraying water injection for the past few months...

03-05-2016, 01:33 PM	#1
Tomnavigator Private First Class 82 Rep 189 Posts Drives: 2010 335D, V-10 Touareg Diesel Join Date: Mar 2015 Location: Southwest Louisiana iTrader: (0)	Carbon buildup Synopsis Cause and Solution (long post) Here is a synopsis of the cause to carbon buildup in the intake of diesel vehicles and the possible solutions. This synopsis is based on known and accepted facts. Facts: 1) Carbon buildup is a combination of oil and soot. 2) The main source of oil is from the positive crank case ventilation (PCV) with possible contribution from turbo oil seal leakage. 3) The main source of soot is from Exhaust Gas Recirculation (EGR) 4) EGR on the 335d is a high pressure EGR. This means that the exhaust is recirculated prior to the particulate filter that removes the soot. 5) EGR on the 335D is active under almost all engine loading conditions 6) Diesel engines generally don’t create soot under light loads. 7) Diesel engines generate significant amounts of soot under moderately high loading (heavy acceleration) Conclusion: First I will give you the background and cause of the source of our oil and soot. Oil mist is generated by high pressure combustion gasses that get around the piston rings. This is called blowby gasses. The blowby gasses pick up oil mist in the engine and must be vented to prevent excess pressure building up in the engine. The gasses are vented at the top of the engine in the valve cover of almost all engines. These gasses were vented to the atmosphere for the first 50 years of the automobile until the government realized that millions of cars on the roads venting oil created a lot of oil in the environment. The idea of venting the PCV to the intake came about in the 1950’s. This was not a problem because oil only in the intake does not create a buildup especially since the gasoline added to the intake from the carburetor washed out the oil. The problem was created when you removed the solvent (gasoline) and added soot (EGR). That is why direct injection gasoline cars now have carbon buildup now also. Diesel engines have more of a problem with carbon buildup because diesel engines create more soot especially when the engine is under a load like heavy acceleration. Diesel engines create much more soot than gasoline engines. This is why modern diesel engines now have particulate filters to remove the soot from the exhaust. Anyone that has owned a pre 2009 diesel vehicle know that the harder you accelerate the more soot you produce. Moderately hard acceleration creates a light black cloud behind you. Hard acceleration creates a dark black cloud of exhaust behind you. Just watched trucks with diesel engines take off and you know that when a diesel accelerates under load that soot is formed. Light acceleration no soot. Moderate acceleration moderate soot. Heavy acceleration heavy soot. Carbon bulid up is formed when oil and soot mixed together form a thick paste that collect in the intake and hardens when heated by engine temperatures. If you remove either component, the problem goes away. Remove all the oil and the soot is a dry powder that won’t stick and gets sucked into the cylinders and is burnt. If you remove the soot, the oil creates a film layer in the intake and the problem is eliminated. Removing oil from the intake will be discussed first because it is easier to accomplish. Removing the oil from the intake is accomplished one of two ways. The first way to remove oil from the intake is to remove the oil out of the PCV gasses with a catch can or a coalescing filter such as a provent 200. A catch can works by providing a wide spot in the line that allows the larger oil droplets to settle out. This removes the largest droplets only. A coalescing filter works using two methods of oil removal. The gasses enter the filter on a Tangential inlet. This tangential inlet causes the gasses to spin acting like a centrifuge to remove the oil droplets. The gasses then move toward the center where a coalescing filter is located. A coalescing filter is a filter that is designed to remove very small liquid droplets that won’t settle out of the air on their own because they are so small. Think of fog which is small water droplets in the air on a cool morning. The oil droplets collecting on the coalescing filter combine with other oil droplets and eventually get large enough to drip off the filter media. A Coalescing filter is much more effective that a catch can. The disadvantage of either of these methods of oil removal is that neither removes 100 percent of the oil. The removal efficiency of the catch can will be related to the length of the line from the valve cover to the catch can because oil will settle out in the line. The Coalescing filter will remove over 90 percent of the oil to probably 95 percent of all oil. The second way to remove the oil from the intake is to actually remove the PCV gasses entirely from the intake. This is done by venting the PCV to the atmosphere. This removes 100 percent of the oil. There are two disadvantages of this method of oil removal. The first is obvious. You are venting oil mist into the air. The second disadvantage is that your car will set a Service Engine Soon (SES) light because you will disconnect the PCV line heater which is built into the plastic line that goes from the valve cover to the intake. A jumper must be placed in the line to eliminate the SES. Removal of the soot is accomplished in three ways. First you can drive the car like a little old lady and minimize your rate of acceleration. This will probably not totally eliminate carbon buildup. But, may hopefully extend the life of the vehicle to 200,000 miles or longer before carbon build up occurs. Only time will tell how effective this method is at eliminating carbon buildup. The advantage of this method is that your fuel mileage will be excellent. The disadvantage is the loss of fun factor by not driving it like a BMW. Second method of elimination of soot is by eliminating the EGR. You can disconnect the motor that opens the EGR valve or block off your EGR. Either method is totally effective and cheap to do. To block of the EGR, just insert a disk in the line that blocks the EGR flow or. The problem with either disconnecting the EGR valve motor or blocking the EGR is that either method generates a SES light and won’t pass emissions inspection. The third way to eliminate the EGR is reprogramming the engine control module to eliminate the EGR. This method is not available stand alone and is expensive because it on only provided as part of a performance coding package. If done right coding out the ERG will not generate a SES but would fail an emissions test that monitors nitrous oxides. What I am planning on doing. 1) I drive it like a little old lady until I eliminate PCV and EGR. I get 40 to 41 MPF on each tank of fuel (using the cars trip computer) on my 72 mile one way commute on 2 lane highway. 2) I will eliminate PCV by venting my crankcase gases to atmosphere through a Provent 200 coalescing filter to remove the oil prior to venting. I will put an oil collection container on the oil discharge port of the provent to collect the oil and dump the container at oil changes. The provent is not required. But, is my concession to protect the environment and only costs about $90 on ebay. 3) I may also unplug my EGR valve and put up with the SES while I wait for someone to offer affordable ERG elimination coding. Editorial note: One day someone will realize that a lot of money can be made by offering an ERG elimination coding cheaply going for volume selling instead of trying to make a killing on one sale. Many people would pay $99 to for coding to eliminate EGR that will not pay $600 to $1,000 for stage one performance coding. Instead they make nothing hoping to make $1,000. There is another way to eliminate carbon buildup. The installation of a solvent injection system in the intake. This works by the continuous injection of a solvent in the intake to clean the intake. The most common solvent injection system is a methanol/water injection system. This method of carbon buildup control will work if injected at a sufficient rate. However, due to purchase costs, operating costs, lack of information about needed injection rates and effects on engine life this method of carbon buildup control is not discussed here.
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03-05-2016, 02:05 PM	#2
Yozh Colonel 870 Rep 2,615 Posts Drives: 2011 335d M-Sport Join Date: Mar 2014 Location: Wet Coast iTrader: (4)	Couple of points. Meth is effective in our diesels and there is plenty of information in relevant threads on how to set it up properly. Just disconnecting EGR or coding it our has had cases of cracked EGR coolers in Europe. That leads to coolant leaking into the intake and one case of hydrolocked engine. This is a reason everyone on this forum has had exhaust manifold side of the EGR cooler blocked as well. There is a proper kit available to block both sides of the EGR cooler, the exhaust and the intake side. And as far as I know, JR does offer a tune that keeps all your emissions intact and codes out the EGR with it's corresponding SES light. It's a performance tune though and as such is not a $99 dream one wishes for. EGR still has to be physically blocked for the reasons mentioned above. And one more. If you want the best "catch can", this is it: defender_500_pd_leaflet_efu00126en.pdf
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03-05-2016, 03:00 PM	#3
335D Alpha Pappa Second Lieutenant 43 Rep 237 Posts Drives: 2011 335D Join Date: Apr 2014 Location: NY iTrader: (0)	2) The main source of oil is from the positive crank case ventilation (PCV) with possible contribution from turbo oil seal leakage. So how does the oily vapors from the crankcase get to the intake? Where is the feedback loop?
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03-05-2016, 03:15 PM	#4
gavronm First Lieutenant 88 Rep 358 Posts Drives: 2011 335D M-Sport Join Date: Feb 2015 Location: United States iTrader: (0)	Not a bad summary. I second the idea that an inexpensive EGR delete "tune" would be an exptremely popular product. I would buy it.
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05-16-2016, 03:47 PM	#6
Monroe New Member 0 Rep 12 Posts Drives: '09 335D Join Date: Mar 2016 Location: Columbus, Georgia iTrader: (0) Garage List 1982 Mercedes-Benz ... [0.00] 2009 BMW 335D Sport [0.00]	Monroe (me) has been building up oily carbon for more than a year. It began when the dealer overfilled the crankcase. Evidenced suggested overfilled by only one quart. Wrong. Months later I measured the overfill at several quarts and suspected from evidence the oil was intended for gasoline engines. Additionally an unknown amount of crankcase additive containing volatile xylene, toluene and another aromatic had by the measuring day, evaporated; meaning considerable crankcase overfill. I bought lunch for a self-employed PhD chemist, who suggested "things will get worse." They have. Please accept my advice about dealer oil changes: Before you retrieve your car, cut a plummers' snake to match the dip stick. Don't drive away until you are convinced the crankcase is not overfllled.
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