cfmistry

Changing the air filter in my '12 C350, I noticed about 5mL of oil sitting in the air intake plumbing (just inside the filter itself). The filter didn't seem to have any oil on it that I could tell.

So I'm not too familiar with direct-injection engines, and I thought I remembered reading somewhere that a little oil in the air intake is normal. Can anyone confirm this and put my mind at ease?

Thanks,
Cyrus

babyboxer1

Was the air filter OEM? I do recall reading about those "performance" after-market air filters like K&N is that they are coated with oil and because the MB intake generates so much suction, it's not uncommon for that oil to get inside the intake. For that reason, I just went to buy mine from the dealer. I don't know enough about the issue to say that's your problem or it might be something else, just passing along some info I found while considering my air filter options. Hope that helps.

cfmistry

This was engine oil, and yes the OEM filter.

Carsy

I know this is a normal occurrence on a diesel. The sump breather is piped into the inlet manifold after the air cleaner so the engine burns the oil vapour rather than ,like in the old days , expel it to atmosphere. When the oil vapour cools on exposed pipework some can condense showing up in the ducting.

If there is not a lot there I would not be concerned.

Oaklandish510

W204Motorsports

The PCV from the driver side head is directly connected to the intake elbow resulting is a lot of oil going threw the intake on most mercedes engines. I put a catch can on that side of the PCV system and the throttle/intake manifold stays really clean now, I will post pictures on my next oil change on how I installed it, its quite easy, you just have to T in the existing hose and there's enough room for the catch can right next to the intake elbow. This is now The K&N filters, yes they come preoiled but you wont see that oil, the fine mist might get on the MAF and make it less efficient, that is the only down side of K&N but the fix is easy, I just clean them with brake cleaner and install them dry, dont use the oil spray or cleaning kit K&N sells because some brake cleaner and water does the job, its simply cotton fibers.

I wouldn't be too worried, you probably removed the intake when the PCV was doing its job and the oil didn't reach the combustion chamber, as soon as you run it the oil going threw the system, mainly it stays in the intake manifold and creates carbon build up or in your case, since its direct injection, build up on the valves, I would definitely recommend a catch can, especially if its a direct injection engine.

superangrypenguin

Bosch engineers have proved that catch cans do duck all when it comes to this. You're mainly catching condensation, as a FYI. This is why I stay away from DI cars.

W204Motorsports

What ? Plenty of catch cans work and should be from the factory but it is a cost the manufacture doesn't want to spend. Off course they work and have been proven by plenty of GTI and BMW owners with direct injection systems, no they dont cure the problem, but they do catch the oil goign to the intake manifold and valves which keeps them clean of oil so the carbon wont be able to stick as easily. Hell I have a friend with a 2007 lexus GS300 with direct injection and he has been using a catch can for years and his car is past 250km with no real carbon build up.

Again, on our cars, the hose coming from the passenger head into the intake elbow tends to put a lot of oil threw the intake system. I have seen it on more then one m272 engien where I remove that hose and its covered in oil. Now Like I said, that is the "dirty side" of the pcv, the driver side is the clean side and mercedes did put a sort of oil separator but I've seen those clogged up too many times so I would also recommend changing it out (Part Number 272 016 0134 ) after 150 000km.


I've been running with a catch can T'ed into the dirty side of the pcv next to the throttle body for almost a year now and the throttle body/intake stay noticeably cleaner and the can does its job on catching the oil not only condensation and does it very well, the out let hose stays spotless while the inlet hose is full of oil and that would all go threw the intake system, so do so more research on how a catch can make you're whole engine last longer and run cleaner.

superangrypenguin

OK. I'll leave it to the experts but you and I have been proven wrong by the likes of Hyundai and bosch

W204Motorsports

Please send me links those articles because it's a mint, there's plenty of experts that can back me and I'm just speaking from experience and results, you believe what you want.

A lot of people just don't install them correctly and yes they just catch moisture and a very small amount of oil but even then, still better to be caught in the can then run threw your engine.

Here's a very detailed thread on the subject, it's for the LS engine but an engine is an engine; https://www.corvetteforum.com/forums...-catchcan.html

Im still waiting for those articles by Bosch and Hyunday as you mentioned. My question to you, you really think manufactures care about long term engine life ? No they don't, as long as the engine makes it threw warranty.

superangrypenguin

I've already bashed this topic to death on this forum and the results from Hyundai have already been presented in the DI engine thread. I know it has because I was the one that brought it up. Please take a perusal.

W204Motorsports

"Bosch engineers have proved that catch cans do duck all when it comes to this. You're mainly catching condensation, as a FYI. This is why I stay away from DI cars."

Then you bring in hyunday,all I see is opinions not facts, im still waiting for those links or at least a factual reason on why on earth they would invent catch cans that dont work .. Which if you look at the link I showed you they obviously do something .. I'm just trying to understand why you're so against it when there's plenty of results out there and its just common sense on catching PCV oil in a can instead of running it threw the intake... It is a must have on direct injection cars.. a must ! It wont prevent carbon build up but it can slow it down dramatically.

superangrypenguin

Sigh. You are entitled to your opinion. Have you ever actually sent the contents of the crap in your catch can to Blackstone Labs. I have also been using DI engines before most of you, when they were even far worse than the DI engines of today. Think 2.0 TFSI engine from Audi.

You're catching a TON of condensate, that's about it. But please, go ahead with using your catch can if you so well please. If catch cans were the answer to this issue than far more automakers would be using it. Think about that.

Here's a thought process. I've been adding a ton of rubber seals to my W204 to quiet down the windnoise, and it really hasn't done much. I had to pause just the other day and think to myself...wow, a bunch of high paying German engineers haven't actually thought what I am thinking of? Clearly not.

And why am I not bothering? Because I don't need to prove something I already know. There's a DI engine thread in this forum which I have already posted at length about, with the results of the GDI testing that Hyundai commissioned in there somewhere.

But alas, I know, there are MANY people who hold your line of thinking. "Wow, I see stuff, this catch can is GREAT", at which just say... "ok, go right ahead and waste your time and money". The improvements to your engine health are marginal at best, but go right ahead. It's a free world after all.

W204Motorsports

I understand your logic but mercedes engine suffer from oil contamination in the intake, when I look inside the intake manifold and its spotless where as before it would be full of oil then I know the catch can is doing something.. You can look at the LS thread I showed you and they have it much worse. The m156 engine suffer from the PCV contaminating the intake manifold and requiring a full disassembly before 200k to clean it up if the oil hasn't eaten away the plastic flaps intake the intake that is which in most cases if the owner never had a catch can or cleaned of the intake manifold, all the plastic inside is probably about to snap.

Again, location is key the catch cans, I've seen them both full of water and some with just oil without condensation.


Don't expect the engineers think of everything because with cost and budget maybe they do think of it but the budget doesn't allow it so they skip it.. The wind noise is really annoying me too, I used some adhesive foam tape around the door seals to push them out and found that the piece of rubber under the side mirrors reduced the most wind noise but I still hear wind which I believe is just the aerodynamics of the car and the glass is just not thick enough to block of the sound, that's just a theory but I would say I've drastically reduced wind noise compared to when i first got it. On my next long trip, im bringing my stethoscope and going to find exactly where wind is getting in.

superangrypenguin

You're right and we're all entitled to our own theories, but here's the thing. ALL direct injected engines all suffer from oil contamination which ends up killing the intake valves. Various automakers have tried, for years, to somehow try and remove the oil before it hits the intakes, but you can thank your local government (or California probably) for insane emissions standards which is why we have this issue of DI engines dying much earlier than traditional PFI do. So yeah, Twitter lives to survive another day as a bird but now we have a car to crush/recycle. Short term thinking made possible by idiotic politicians who don't understand anything about cars.

ANYWAYS, I guess my point I was trying to make is that MB engines are not unique in the fact that there is unburnt fuel and oil vapors (and others) that end up clogging intake valves. Audi has had this problem, BMW, etc. I've seen hundreds, if not, thousands of enthusiasts much like you and me try to address this by trying to move some of the gunk from our engines - and these attempts are laudable and we all are trying to just make our engines healthier as I think it's safe to say we all love our cars. The reality is though, I have not seen one thread whereby someone goes..

From 10000 miles to 20000 miles, I didn't use a catch can. My intake valves looked like this ->
From 20,000 miles to 30,000 miles, I did use a catch can, and wow my intake valves are clean!

That's the sad, but inconvenient truth. Can you prove that running a catch can has drastically cut down on intake valve buildup on your car? Are you able to post pics?

W204Motorsports

No I dont have picture, sadly my brain cannot upload pictures but on my next oil change I will do a write up on how to install a catch can and Il take a picture inside my intake manifold and throttle body looking like new and my car has 240 000km. I will get pictures from my friends c230 next time I work on it and show the difference on a normal looking intake, it will be covered in oil.

Now like I said, the catch can isn't a cure for direct injection cars, its not the secret fix for carbon build up but it will reduce the buildup since the head/valve/intake wont be covered in a a mist of oil which makes the carbon stick to it. My friends GS300 has had a catch can for years and last time we looked down his intake it looked acceptable, granted he has both direct and port injection which helps a lot but almost 300 000km and no real build up issues.

Like you said, stay away from DI engine or try to get the port and DI ones at least, DI on its own is just looking for trouble in the long term and a catch can is just a bandage that will keep it from bleeding for a while but it will bleed at some point..

superangrypenguin

Fantastic. thanks for your help and for the discussion this lovely Monday! I genuinely look forward to the results!! (I'm being 100% serious, this could be a game changer for me!!)

edgalang

Then I will take on this task/challenge and report (assuming you guys are still around). I special ordered my M276 from the factory and have had every mile accounted for thereafter. I currently have 96k miles and the plan is to get it to the 1st high mileage award before selling (155k miles/250k km). At a rate of 20k miles a year, I'll hit this in roughly 3 years, and as promised in my previous threads/posts I will report it all. At 100k, I'll take a look inside the engine air filter housing to check for any oil residual.

superangrypenguin

I have been begging for this for years. Please do, and kindly post your oil that you use and the oil change interval. I think this would be better than watching **** for me. Really REALLY interested. Thanks in advance!

W204Motorsports

The filter wont have any oil, the pcv is after the MAF sensor, oil stars at the elbow/throttle body and beyond. Your engine will probably look better then someones who only drives 5000k/year since you're burning off some of the carbon, driving it hard also helps a lot, people with the m276 should at least floor it a few times a week to get the carbon loose because once it starts accumulating and building up, flooring it and high way drives wont really help, looking forward for your results.

superangrypenguin

Oh no, here we are again

Ok, so I used to do this too as I believed the same thing. Two things.

1) Every study I have that talks about flooring it and such "to dislodge carbon" have found that it isn't the case. (for DI engines under WOT only).
2) That said, I cannot explain why when I did do this, there'd be a HUGE cloud of black smoke out of my car.
3) And if it were true, you're dislodging a bunch of carbon into your cats. That's not necessarily a good idea.

Youtube has a bunch of before and after videos of people using injector cleaners and testing via a boroscope. Even with PFI engines (in their case) AND with using an injector cleaner, AND with flooring it, they weren't able to dislodge carbon (in 95% of the cases).

Again, this doesn't explain #2, and I can't for certain say if you're right or wrong, and it probably doesn't harm anything if you were to floor it now and then, but then it completely negatives the positive fuel economy gains with DI.

Catch 22, sadly.

W204Motorsports

No injector cleaner cant ever work or if it does it barely will because the injector will never shoot the cleaner behind the valve where most of the carbon is. However, its known that people that drive DI cars more spiritually will have less carbon then people who do short trips, why ? Because the engine and combustion temperature are higher and the carbon tends to burn off. Now for the black smoke, not its not too good for your cats but I would just drive it hard after something like black smoke coming out to burn off wtv came out of the engine in the cat.

Im surprised you actually saw black smoke, must off been a nice chunk of carbon that flicked off or you have some serious fuel system issues and the pump spiked resulting in a very rich mixture but that would throw a check engine light for sure.

superangrypenguin

I don't think I got my point across, sorry. My point was that in the best of conditions, which is an engine that utilizes PFI and when a user uses a fuel injector cleaner, AND the user floors the engine, if that won't dislodge carbon, then a DI engine where fuel doesn't touch the intake valve (only blowby gases if one uses a fuel injector cleaner that is based around PEA which survives combustion) then nothing will.

I've heard the other theory you brought up regarding a hotter operating temperature, and with my good ol' VAGCOM I could actually see some of these values, there is no way you are running your engine hot enough to make baked on carbon deposits more volatile. Audi tried this in the 2.0 TSI engine (from the TFSI) engine by increasing operating temperatures by 10'C (or Fahrenheit, I don't remember). Obviously this didn't do much. The reality though is that unless you're willing to operate your temperature to the point of melting for iron/steel components, you really haven't operated the engine hot enough to affect carbon deposits.

As far as black smoke goes, keep in mine ALL DI engines in N. America run rich and can't enter the ultra lean burn mode because of the shoddy sulphur amount in our fuel, which further makes worse the issues with DI. Yes, I'm certain a fair amount of carbon was ejected in my case, but what I can't explain to you is why. The operating temp of any modern combustion engine isn't hot enough to affect carbon. My only guess is perhaps the car was operating in a rich burn mode or if there was really really light carbon that was blown out (all Audis have black tail pipes), but that said, anything that is baked on onto an injector is stuck there for good, short of walnut blasting or if you use the BG intake valve cleaners if you believe their stuff work. I've used it twice (BG44K or something?) My before/after boroscope exams didn't show anything conclusive thugh.

W204Motorsports

Audi's exhaust tips are always black because those 2.0/1.8T love burning oil which is probably why VW/Audi seem to have the most carbon build up issues. Yes the temperatures would have to be really high for large carbon particles but the key is the drive it hard with quality fuel since it was new/low mileage to prevent the build up or at least slow it down, once you have a lot of carbon already built up it's too late and taking it apart to clean it is the only way.

I had this issue at around 180k with ping happening under load. I looked down the spark plug hole with a boroscope and it was pretty dirty. The car was always ran with quality high octane fuel and I use chevron twice a year. With new sparkplugs/MAF and no check engine, I knew it was soem kind of carbon issu in the combustion chamber so I ran sea foam threw the intake, twice and never heard pinging again. Looking with my boroscope, there was definitely a difference but just the fact it made it stop pinging is proof on its own. Note that it was a very minimal ping, happened only after long drives or under certain temperatures and acceleration.

Cats also seem ok even tho the first time I sea foamed it, the smoke was ridiculous, the second time wasn't as drastic.

Anyways, all this I believe was caused because of Mercedes poor design of the PCV which lets a lot of oil into the intake and eventually into the head and combustion chamber, this is why I also run a catch can ever since and the carbon doesn't stick to the engine as easily, I know this because I look down my intake manifold and throttle body every oil change and there they are no long covered in a mist of oil.

Knightmare69

Actually I have, they couldn't identify it. It smelled like gas but I tried to light it on fire with no results. It was brown and sludgy, almost rust colored. Let me see if I can dig up the Blackstone report.

*Edit, found it.