adding a secondary oil separator

A6 All/ S6 All
#1

While my top end is apart I have been looking and thinking about the whole carbon and oil mist problem. Our stock separators basically have the little membrane to regulate the vacuum, one drain hose, and one suction side which seals with an O ring to the manifold.
What if one were to make a bracket to offset the separator and put an adapter from the outlet of the adapter, to a hose leading to a remote separator, then feeding back into the intake?

Or what if one were to ditch the stock one completely and just run an aftermarket one? the Mishimoto one looks nice, APR is nice too along with ECS but they want crazy money for it…

anyone add or replace the stock oil separator?

#2

been thinking about this myself.

company here in Canada makes a heated vortex oil separator with a remote tank for the oil. Makes the catch can a bit smaller, you can use the existing heating lines and the remote tank can be emptied from under the car. Pretty cool. I need to get on the ball and get mine ordered.

I need to provide hose diameter for the stock PCV and take some pics to send him. Not sure the cost but assuming in the $400-500CAD range.

www.kustomlab.com check out his facebook page for pics and details.

Also has some trick water meth kits available.

All around good guy.

#3

Hose diameter is 1" ID

#4

This has been a topic that has been out and going for about 8 years now and since the V10 FSI is unexplored except for us here on AR this topic makes sense to come out sooner or later.

Let me share where guys like the RS4 \ A4 FSI guys are at after 8 years of messing around.

The thing to start with is to understand that your oil seperator and PCV system is set and balanced in the fuel system. What I mean by this is that if you mess with your PCV system your going to get codes and have fuel trim issues as if you have too much flow your going to get a lean code and if you dont get enough flow your obviously moving backwards with trying to create a better system to help oil mist.

So after testing and testing the RS4 guys have found that anytime they get soemthing that even remotely works they get fuel trim codes because they basically made a PCV system that has the car thinking there is a vac leak somewhere but even with the best results what are you really getting. You still need to pull crank case pressure out of the bottom of the motor to help seal the rings and that in itself has oil and water vaper in it.

All in all really think about this tho. We are looking at cars that have gone 80k with no real maintantence and carbon build up over 80k. Its not like carbon clean up is something you have to do every 5k or even 10k. I look at carbon cleaning as general mantantence every 35 to 50k depending on your driving style.

Thats not to say that anyone here cant try do find a better box. I just wanted to point out what I have seen and what seems to make sense when looking at the possible downsides of trying to fix an issue thats really only an issue ever 50k

#5

I spent a substantial amount of time looking into this myself when I first got my car. What I found in my research was pretty much what Justin said above - they never work as well as they should, if they even work at all, they screw with your PCV system and make your car not run right, and at the end of the day carbon-cleaning really ain’t a big deal as long as you remember to do it every couple years. If you pay someone to do it, you’re looking at about $800, which is roughly $400/year. Even if you found a catch can solution that worked, you’ll still need to do carbon cleanings, just maybe slightly less often.

So I ditched the concept in favor of just simply keeping on top of regular maintenance.

#6

i see. THe one issue i did for see is adding another in line separator, have more hoses etc etc the pressure drop is greater over the whole length, and then the effective suction is less, thereby like you mentioned justin, the whole system less efficient in the first place.
THe carbon cleaning definitely aint so bad once i learned some tricks to do it all quicker. Just hate having to deal with pulling injectors, cleaning them etc etc. Although mine werent too bad, i think worst one was 6% down on flow from the highest one. Now they are all within 3% Next time i will probably just leave them…

#7

I thought you could help decrease the likelihood or rate of carbon buildup through running the engine through its paces regularly? Same as the R8 guys right? High heat breaks down the buildup I thought. I could easily be wrong though lol

#8

Thanks Justin. I didn’t really get around to thinking about the repercussions of messing with the PCV system… the catch can I was eyeing is smaller than typical, I’d be willing to be similar in volume compared to the stock system, what I do like is the remote reservoir that doesn’t dump the oil droplets back in the engine, altho I’m not convinced there is that much oil that makes it back.

I would like to reduce the oil in the intake manifold, when I removed mine and took it apart there was a good 5 or 6 oz of oil just sitting in the bottom of the intake. But perhaps I should be changing the factory oil separator once a year instead and might see an improvement.

I was also toying with the idea of meth injection, as a pre-emptive way to reduce carbon buildup on the valves. Haven’t seen anyone try it out yet however.

Snow performance has one that runs off a MAF signal, and I like that concept.

#9

no. in fact high load engine operation whre there is most blowby is most conductive to carbon buildup. This is fact and an italian tune up will not help with carbon build up. low to moderate engien loading will prolong the amount of time between cleanings. This is simple physics, as the single biggest contributor to carbon build up is blowby gasses which contain oil.
a few SAE articles and tests were conducted in a controlled manner to determine what kind of engine operation causes the highest amount of deposits.

although i cant post the actual article, here is the conclusion from it:
SUMMARY/CONCLUSIONS
• A standardized, vehicle-based GDI IVD test has been developed
that is both repeatable and responsive to known additive chemistry.
• Higher engine-loads lead to an increased rate of deposit
formation.
• IVD formation in this protocol is an oil-related process, and
the majority of the oil that finds its way onto the intake valves
comes from the PCV system.
• The oil leaving the crankcase through the PCV system is whole
oil containing additives and contaminants (not distilled base oil
vapor which contains no additives).
• PCV gas flow in the intake manifold is inconsistently distributed
among the eight runners of the manifold leading to the valves.
• Inhibiting the carbon-formation process lessens the rate of
deposit formation on the intake valves.
• Oil consumption past the rings bring both additive and nonadditive
elements into the combustion chamber where they are
incorporated into the exhaust-gas particles.
• Particles found in EGR exacerbate deposit formation rate.
• Particles found in EGR appear to incorporate combusted oil
additive components, engine wear metals, and ambient air
contamination.

#10

I have heard of one guy running meth injection on a c6 s6. I think there is some really good upsides to doing it. Obviously you have to then maintain the meth system and fluid levels, but hell the m4 GTS runs meth from the factory so it’s doable

#11

Yes kinds of. But what Greg posted is also true but you need to put it into context.

Any time you can create a situation where the in coming air charge (ICAC) is cleaner with a higher velocity and density then the crank case air charge (CCAC) your in a better environment. So doing a few WOT pulls every time you drive is a good thing.

Before I go into the explanation the best way to keep the car running well is maintantence and keeping ontop of your oil levels and keeping your oil in good shape.

What Greg posted is 100% true but… the higher engine loads that are conducive to the build up of carbon are… lower rpm higher motor loads were the percentage of CCAC is at a higher percentage and in some cases equal to the ICAC. This would be when your at say 8% throttle but in high gear where the motor is straining or chugging a bit that is to say the motor has a high load on it. These situations create a point where the CCAC is very elevated.

Ideally you always want the larger percentage amount of ICAC over CCAC. That will happen at WOT. The times where carbon build up is when the percentage of CCAC is at its highest compared to the ICAC… This is when your brining in less fresh air (ICAC) and the motor is pulling in more oil air (ICAC) Genreally its pretty impossible to have more CCAC than ICAC but you don’t want the percentage of CCAC to be close to the ICAC.

let me try to explain.

Situations that are high load are slow take off and slow speed driving with constant slow and go. The PCV baffle spring is supposed to reduce the amount of flow at less then optimal conditions but its a spring and things can be made worse if you have a rip in your PVC baffle.

To try and say it another way to help those that might not be following along. ITs like this.

You have two major inlet points going in to your intake manifold and feed into the motor. One point has your throttle body on it and that is roughly 3" and then you have your PCV oil separator and that is about say 1".

Your motor is pulling air into it and it will take air from where ever it gets it. This is why vac leaks cause misfire and fuel codes because the motor is pulling air from a spot that is not measured by the MAF… but let me get back to the point.

You have two points of air entry one from the throttle body (fresh air) and one from the crank case or PCV system (oil or dirty hot air) For ideal power you would just take off the PCV system all together as the oil hot air makes for less power and builds up carbon. But we have a PCV system and we actually need it so lets get again back on track.

******* THIS IS JUST MEANT TO BE AN EXAMPLE I suppose I could do the math on volume and PSI and CFM but this is to help everyone get an idea on what’s going on **************

So your driving and your giving the car little throttle but your going up a small hill. As the car has to go up the hill… the LOAD of the motor or how hard the motor has to work to keep the car going up the hill goes up. In this example you keep your throttle (FRESH AIR) in the same spot and say the throttle plate (FRESH AIR) is at 10% throttle…but since the motor is getting more load the motor is needing and pulling in more air but your throttle position hasn’t changed so now the motor is getting and pulling more air from the PCV system(OIL AIR)… so its now getting a higher percentage of oil air then it was before but your amount of fresh air hasn’t increased… this is true of every time the load goes up and the throttle air amount and the PCV air amount are closer in total amount.

Basically you always want to keep the amount of fresh air well over the amount of PCV air coming into the motor. A good way to see if your motor load is down is to check your instant MPG the better your MPG is generally that goes in line with your motor load…

When you go WOT the amount of fresh air WELL EXCEEDES the amount of PCV air by a grand amount as the PCV system will get to a point where it can’t match the flow of the bigger throttle body your still getting a oil charge but the percentage of oil to fresh air is in a better balance percentage wise.

I don’t know if that made any sense but that’s the best way I can explain PCV percentage air Vs fresh air for carbon build up.

IS an Italian tune up going to get rid of carbon… no probably not I don’t see how it could… if it could youd be sucking carbon into the motor and that would not be a good thing…

Whats the best solution. Maintain the car keep the oil separator in good working order. Keep on top of your oil changes your gastkets etc.

#12

The oil separator has a drain hose that goes back in the pan so its not a terrible system. I think its important to inspect the oil separator and make sure to keep it clean and functional.

I think the big thing we all need to keep in perspective is that we are cleaning cars that have been owned and almost never carbon cleaned or owned and never had the oil separator looked at let alone the PCV system as a hole. After you have done the carbon clean work you really shouldn’t have to do anything for over 35k miles.

There are always cases where maybe the oil separator is broken or a check valve is bad and your getting too much oil pull into the intake but this would fall under maintaining the car and doing basically what the owners before us never did.

Jimmybones made a few great posts on carbon and just what we are talking about. I did a seach as he is an ex Audi master tech so he has seen it all.

The basic part of what he has said and the Audi study guide and reports from people backs up is that we need the oil separator and the amount of crank case vac that we have. It controls the rings sealing properly and actually helps make more power due to keeping compression and less ring blow by at high rpm.

Jimmy gave a ton of great suggestions some that come off the top of the head to keep carbon at bay. Here are a few good ones I remember

1 don’t idle your car or let you car sit at idle if you don’t need to.
2 don’t over fill your oil
3 don’t let your car sit and warm up on cold days. Start and drive
4 don’t lug the motor (drive under high load operation where you have limited throttle opening)
5 clean and check your PCV system when you do oil changes
6 drive on the high way over taking side streets. The higher rpm and air flow is good for the motor.
7 Remember your always pulling oil through the PCV system… having higher rpm and more incoming air from past the throttle body pulls the oil vaper into the cylinders vs letting the oil come in at a slower weaker pull where it falls and can cling to parts.

Those are some good tips that I remember jimmy and few other Audi techs pass on. Over all good stuff to live by along with a good maintantence practice.

#13

So much helpful info here, this is the main reason why I think AR is the best online source for our V10 motors.
I’m not a gear head so i pretty much take the info here as gospel in fear of getting ripped off at the dealer.

Thanks again for the info guys.

#14

mpg = >carbon build up got it!..i think I remember a jalopnik article about this a few years ago, with that in mind ive always drove spiritedly when possible! Does the quality of the synthetic oil have a factor in the carbon build up i wonder? I’ve been using the liqui moly hitech 5w40 with their ceramatec additive @ 5k intervals

#15

getting solid data is hard so for me I take what I have seen along with the other repituable people I know and talk to

Good synthetic oil seems to help play a roll by not braking down as easy. So it makes sense and liquid moly is a GREAT oil so I would say your in good shape. 5k is just about right to make sure the oil isn’t braking down. Some say you can go longer but when you think about how our oil is getting used in a hydrolic fashion to move both the intake and exhaust cams and the tensioner system I think to me it makes sense to keep the oil fresh