I feel stupid. I have been searching for an hour now and a) can not seem to definitively determine if my car has a PCV, oil separator, both or other and b) where any of these things are. As I browse I keep reading conflicting things. And the descriptions where they are, no pictures, are not extremely helpful. And, unless I am suddenly searching incorrectly YouTube is strangely unhelpful. It looks like it might be a part of the valve cover?? I am so confused.

There was a small amount of oil in the body throttle and idle is a bit rough. I drives well otherwise. So I want to check/replace these.

Any help would be greatly appreciated.

 

Which engine do you have?

 

Great question, 1.8L FI Turbo DOHC 4cyl. This maybe? 271860 30 687446 I got that running my VIN through https://www.lastvin.com/. If you are looking for something else you'll have to tell me how to find it. Which woudl be very helpful to know.

 

You have the 271.860 engine.

You have the 204.047 submodel. This is good to know when looking up parts diagrams. Heres a link to your parts diagrams. For the diagrams below I was looking in the "M. Engine" subsections. https://nemigaparts.com/cat_spares/e...fg/204047/61r/

I dont have that engine but ill link and post to some diagrams you can look thru. I think your pcv is in the plastic cylinder head cover. The "Engine Breather" lines lead to the cylinder head.

 

Heres a thread I came across. may have some useful info. : https://mbworld.org/forums/c-class-w...pcv-valve.html

 

Thank you. Will look through these tonight

 

I had browsed that thread before but this morning I read it more carefully again. Unfortunately it is not as helpful as I would like.

For starters I already replaced the air intake turbo hose as several suggested. That did make a difference at the time.

In post #3 it mentions and has links for a breather hose check and oil separator. I found the check valve and will replace that but I still have no idea where it is in the engine. I'll look at the parts diagrams. I don't think the oil separator applies. When I look it up on several vendors they all say it does not fit my vehicle. So I m still chasing that down. And I notice that no one ever addresses that in the thread. Post #15 specifically asks and no-one answers.

I am going to look at the Turbocharger Oil Line. I'll look for a leak before buying but that definitely seemed to help others. But wondering how that would make the idle less smooth and add oil to the body throttle.

I also want to try and figure out the whole banjo bolt thing. But again, if no oil leak then I am not going to replace it.

I truly appreciate all your help. Going to study the parts diagrams now.

 

Funny, I watching to videos abut replacing the turbo oil line. One had a banjo bolt and one does not. Looking in my car there is no banjo bolt. I think there might be a leak from this so I am going to replace it. But again I assume this would not account for oil in the throttle body.

I was looking at this thread as well, https://mbworld.org/forums/c-class-w...e-oil-cap.html. But my oil cap dos not bounce around the way theirs does, https://www.youtube.com/watch?app=de...ature=youtu.be. It stays well seated when I unscrew it. It makes the same sounds as when he lifts it off in the video but I assume any engine would make that noise with it off. I don't mind buying a new valve cover but I hate to put the money out if that is not the problem.

So I guess based in this forum, https://mbworld.org/forums/c-class-w...her-issue.html, I will replace this part, . I think I will go in from the bottom rather than take all the parts put.

 

Those valve flow a specific way so make sure the new one is facing the same way.

That valve is showing as only $12 at my local MB dealer, if you have one close. I prefer Mercedes parts in general over aftermarket.

 

Hey ​​​@jeiholzer - I believe I replied to you on another thread a few minutes ago.

yes our cars have a PCV with the check valve that I sent over on the other thread. As well as, an air/oil separator that is built into the valve cover. The air pipe is the black plastic pipe on the passenger side of the engine. It connects to the side of the valve cover by two screws, and runs to your air intake.

there is a check valve/flap inside the valve cover that seems to get clogged and stops the flow of air/oil separation. I have a video on my YouTube of when I cut open the valve cover to show what’s inside.

let me know if you have any other questions. @TimC300 is also a great resource


ant

 

@jeiholzer - also check this video out. I was researching this issue a year ago when I was running into the same issues as yourself.

at 5:45 they go into the crankcase and PCV system overview. Hope this helps



ant

 

@antboii Thank you very much. And yes @TimC300 has been very helpful on this thread and another thread of mine. That video is interesting. I am unfortunately not as technically minded as I would like. I am happy to work on my engine all day but clueless with diagnostics. I am not seeing the same issue with my oil cap as you did so for now I am going to just replace the lower PVC system. And probably do the valve cover if this does not fix the issue.

Again, thank you both.

 

For the breather tubing I am fine pulling everything to get down to it but it woudl be nice if I did not have to. From your experience do you think it is possible to do from the bottom? Or would it be easier in general to do from the top with everything pulled?

 

@jeiholzer - definitely have to replace it from the top because all of the vacuum lines come up and through or around the intake manifold.

there is also a quick connect fitting on the bottom side of the intake manifold that is tricky to undo, as a heads up.

Depending on your cars mileage, I would get an intake manifold gasket kit incase you roll a gasket or they are old and worn out.


ant

 

Ok, good to know. Thanks for the heads up on the gasket kit. That is the thing about all this stuff; all the extras you need to have just in case..... oh well.

 

I am going to try first thig in the morning. Wish me luck. If you have any general advice I am open to it. One more question though. Do you happen to know if there is a torque specification for the bold holding the intake manifold to the engine?

 

There is a torque spec for just about every nut and bolt on the car. I even found torque specs for the screws that hold the plastic under trays on (12.5ft lbs by the way).

I dont have the specs for the M271.860 but came across them for the M271.940.

 

Heres the instructions I found for the M271.940. May be of some help.

 

I cannot get the manifold t come off. I removed all 8 bolds but I feel like I am missing something.

 

Found it, I had to get the air box out to even see the ninth bolt. I can't get a socket on it due to the oil filter housing. So need to figure that out

 

Torx head bolt? I find a closed end wrench works, just have to find the correct size. I remember working on a breather cover I couldnt have done it without a 12 point 5/16 wrench, no way to fit a socket on with the firewall right there.

 

Success!! But now my oil cap bounces around so I guess the valve cover is next. I guess I should have bit the bullet and just got one. As a result I feel like it drives a bit better but the idle is still not smooth. Not super rough but not smooth. Oh well.

Still can't decide on investing in e-torx wrench given that I only needed it for one bolt. Not sure it is worth it.

I really appreciate both of your help very very much. Thank you.

I'll let you know how the valve cover goes. At least it should be a lot easier than that. (I hope)

 

5/16" and 3/8" 12 point closed end wrenchs seem to fit the common smaller torx head bolts just fine if you have them on hand. They arent high torque so shouldnt round off easily. I found metric wrenchs are too loose, a bit too big.

I find Amazon a great place to buy random tools. Look for the "used-like new" deals. Can always return them if you dont want/need them.

 

Yeah, Amazon is great for that stuff. I guess I should not be surprised that none of the local auto parts or hardware stores carry them.

 

@jeiholzer - awesome man ! Glad you got it all figured out. I was traveling yesterday and wasn’t able to pop on the forums.

my car still does the oil cap jumping and I’ve concluded that it’s because when you open the oil cap while running , we disturb the vacuum system. It’s not longer a complete sealed vacuum unit.

If you plan to do the valve cover, I would get a genuine OEM Mercedes valve cover.