I think my engine vacuum is too high. I can feel the negative pressure when I loosen the oil cap at idle.
I remember reading a thread about the sucking sound, but I can’t seem to find the thread. What does it mean?
I know I’ve changed the oil separator and feeder hoses in the past 6 months…
The motor vac is suposed to be high. Something to check if your worried about the motor health try a compression check. The intake track has alot of vac on it you want to make sure there is no outside air leaking past the intake
Compression check was fine for all 10 cyls.
This was the post I was searching for-I can’t seem to find anything from Tapatalk.
http://audirevolution.net/forum/index.php?topic=3967.msg113423#msg113423
My mechanic did spray as directed in #2, but didn’t hear any change from the engine. He did not measure fuel trims.
But my problem is #1, the oil fill cap does not come off easily. Is there a way to tell if the oil separator is bad without taking it apart to check the membrane? It is only 8 months old…
i looked for a crankcase vacuum spec but did not find one. Once someone finds the spec, put a manometer onto the dipstick tube and see if its within spec.
my oil separator pisotn was stuck in full open resulting in excessive crankcase vacuum and oil pullover rate. replaced with new one (could also clean old one) and it is noticeable less vacuum and no unusual consumption. Never did find the actual spec though.
I could take out the oil separator, but hoe do you “clean” it? What am I looking for?
For number 2 you might not hear a change as the car can adapt the fuel control very quickly but you wont know that unless you look at vag com as described. You really need to look at vag com for that.
As for the PCV you have to be careful cleaning it as things like brake cleaner and other minerial spirts are harsh. One good way to test the oil seperator is to pull it off and blow a low amount of pressure into each end. The air should never make it out the other end. If you get air out the other end youll know to pop the cap and inspect the memberane
^justin, you will get air out the other side, this separator for the v10 doesnt have a check valve in it. It is elsewhere in the PCV routing. Albeit, when you blow into the foul air inlet side, it should have some good resistance, i just put some hose over ti and blew with my mouth so i had a subjective account of old vs new. Old one was easy to blow thrrough, new one not as much.
Also once i took the separator off It was clear the old piston was retracted almsot all the way (exposing 2 or 3 of the cyclone chambers-also creating a larger orifice at the time, which means high vacuum pull on the crankcase). I used engine degreaser (much more gentle than brake cleaner) in it and diddled the piston back and forth untill it was free to move. I also popped the cover off to inspect the diaphragm, but it was ok.
I replaced the unit with a ebay china version as I had it on hand (didnt want to be stuck with no valve if i pulled the old one off and say it was fuibar’d). china version working fine, but if it fails I will put the OEM one back on.
http://uploads.tapatalk-cdn.com/20161007/41a2859dc1ade9fd27a1f8357668631d.jpg
I got the oil separator loose, but I’m not sure how the hose clip works on the connection that drains to the oil pan below.
But I’m not sure how this is supposed to work. If I blow on the inlet side the air goes right through—I’m guessing to the IM outlet.
If I cover the IM outlet and blow again, there is much more resistance, but I can still hear a air leaking to somewhere—to the old pan? I’m not sure which path the membrane is supposed to regulate.
http://uploads.tapatalk-cdn.com/20161007/b9711d9b201ef91444a4d34cfdc1664b.jpg
Any idea if this is functioning properly?
Ill post more pictures and get pictures on this later today
The oil drain has a one time use clip and your going to need to remove that if you want to get a good test.
The most top part is from your crank case and that part should flow with out much or any restriction. But when you blow you want to make sure you can hear and see the piston slide back and forth as this plays an important roll.
The middle hole is where your diaphram is at. And you did the test right you want to cover the inlet and make sure there is some resistance. When i say low pressure I really mean low pressure.
The air you hear leaking is into the oil pan. Now if you remove the unit you can blow into it and you should no be able to get any air to go in. when you suck in and be careful sucking in on the oil drain side you might get a oil suprise you should be able to hear the membrain crack open.
For reference ill post up pictures on how all this works later today. So far as long as your piston slides on the top part it sounds like you should be good.
Care to post the results.
Also If you can pull the cap off the car and it stalls then I would start to worry. The oil cap is going to be under negitive pressure as that is part of how it works. Too much negitive pressure will result in the car stalling when you pull the cap off as that now creates a huge vac leak and if the PCV system diaphram is not sealed up right there will be too much air passing by
I don’t have the compression results, my mechanic did it before he replaced the injectors.
But here is a video when I remove the oil cap - it almost stalls.
I put in a new VAG oil separator less than 1 yr/6000mi ago. 
I would say that looks about right. If you want to see about how hard the PCV system is pulling pull up both of your air intake tubes and expose the air filter just under the maf. Remove your air filter and put your hand infront of the inlet that plugged into the air filter. You will be able to feel at idle just how much air the motor pulls in.
The PCV system plugs into the passenger side inlet tube the crank case is getting its air pulled out by the use of the intake track. So there is going to be a good amount of vac.
A healthy car should see about 15 to 17lbs of vac
“It looks like right” means maybe not a problem? Cause I’m also trying to track down the P0024 fault with the cam sensor…
Yes I dont see anything wrong with how the car reacted when you pulled the cap off. Also if you did have a tear or an issue with the PCV you would generally also get a lean codes as the car would be pulling in a good amount of un meatered air.