Lots of air coming from the oil cap

Posted by Benshooter, Jan 12, 2010
Maintenance & Repairs - Oil choices, timing belt, setting timing, CV boot replacement, alternator servicing, fuse/relay checks, and other basic maintenance, repair and diagnosis discussions.

  1. Benshooter

    Benshooter Proven Member

    Joined:
    Dec 9, 2009
    Posts:
    205
    Likes Received:
    3
    Las Vegas, Nevada
    This is a bit of an extension on to my post about my low compression numbers...

    I had the car warm and at idle this morning and I pulled off my oil cap and noticed a very good amount of air was being blown out of it. Not just a little, a lot.

    It's not blow-by, my rings are fine... And it doesn't smoke unless I'm hard on the boost, and even then, it only smokes a tiny, tiny amount and not all the time. I couldn't even notice it until I had someone drive the car in front of me as I followed, so I'm guessing it's not the exhaust valves...

    Could it be the intake valve seats? Possibly even the seals or stems? It seems like I've narrowed it down to that but I don't want to perform any unnecessary work since I'm on a budget for the next month. Maybe the big web cams weren't ground properly?

    And yes, I have a new OEM PCV valve installed...
     
    #1
  2. ramsack

    ramsack Banned Member

    Joined:
    Dec 27, 2007
    Posts:
    2,196
    Likes Received:
    13
    West Lawn, Pennsylvania
    yeah i tried adding oil once with the car on and it just sprayed everywhere. it is normal. there are pulses of air from the pistons going up and down.
     
    #2
  3. LiquidX

    LiquidX DSM Wiseman

    Joined:
    Sep 19, 2008
    Posts:
    6,591
    Likes Received:
    79
    Anywhere, Pennsylvania
    How is your turbo?
     
    #3
  4. ramsack

    ramsack Banned Member

    Joined:
    Dec 27, 2007
    Posts:
    2,196
    Likes Received:
    13
    West Lawn, Pennsylvania
    why would the turbo be blowing air into the valve cover?
     
    #4
  5. LiquidX

    LiquidX DSM Wiseman

    Joined:
    Sep 19, 2008
    Posts:
    6,591
    Likes Received:
    79
    Anywhere, Pennsylvania
    If your seals are bad you will blow air into the block which makes it to the head and inturn blows air out of the cap. Doing a boost leak test off of the turbo will help determine that. I'm stating that because you burn oil on boost and a little at idle.
     
    #5
  6. Benshooter

    Benshooter Proven Member

    Joined:
    Dec 9, 2009
    Posts:
    205
    Likes Received:
    3
    Las Vegas, Nevada
    It has some lateral play, I'd saw a few millimeters, but even if the seals were shot, I'm still pulling 10-12 hg/in vacuum at idle, so I don't see how it would be blowing a ton of air into the crankcase...
     
    #6
  7. ramsack

    ramsack Banned Member

    Joined:
    Dec 27, 2007
    Posts:
    2,196
    Likes Received:
    13
    West Lawn, Pennsylvania
    if the seals in the turbo are bad then oil will be leaking out into the turbo, not air leaking in. and why would there be boost at idle? even on boost the air pressure isn't enough to overcome oil pressure. it is normal for oil to blow out of the cap like that. happened to me on my NON TURBO like i said about adding oil when running. it is actually blowing in and out very fast but you will only ever feel the outward pulses.
     
    #7
  8. LiquidX

    LiquidX DSM Wiseman

    Joined:
    Sep 19, 2008
    Posts:
    6,591
    Likes Received:
    79
    Anywhere, Pennsylvania
    Well, at idle you should be around 15-20 inHg unless you are running a different grind cam. Updating your profile will help though.

    Maybe so, but I still said to do a boost leak test to test the seals anyway. I know that pressurized air should NOT pass the turbo shaft seals and if it does, it'll go into the block. You are correct though that air SHOULDN'T blow into the turbo but burning oil during boost is a symptom of turbo seals going out.

    I've poured oil into my car while running and haven't had any blow out before. Both turbo and non turbo vehicles.
     
    #8
    gingerbredman00 likes this.
  9. Benshooter

    Benshooter Proven Member

    Joined:
    Dec 9, 2009
    Posts:
    205
    Likes Received:
    3
    Las Vegas, Nevada
    I known that most engines will have some air coming out of the breather/oil cap but I've never felt an engine push out nearly this much air and I suspect it of having something to do with my 120-124-126-130 approximate compression numbers.
     
    #9
  10. ramsack

    ramsack Banned Member

    Joined:
    Dec 27, 2007
    Posts:
    2,196
    Likes Received:
    13
    West Lawn, Pennsylvania
    ok, i agree with you on some points, but oil seals in the turbo would have nothing to do with his problem. that is a LOT of air to be leaking by them which is impossible. i would be looking at your rings then you have pretty crappy compression numbers.
     
    #10
  11. Benshooter

    Benshooter Proven Member

    Joined:
    Dec 9, 2009
    Posts:
    205
    Likes Received:
    3
    Las Vegas, Nevada
    When I bought the car the owner had written down on the mod list "Big Web Cams" and he said they're the common 272/260 set up. Notice I mentioned the big Web cams towards the end of my post :) Ive heard that these have some serious QC issues and if the lobes weren't properly machined on the cold side, it's possibly it may not be allowing the valves to close and fully seat. I'm wondering I anyone else has had similar issues with Web cams

    Just ran a BLT for fun from the turbo inlet and capped off the UICP. Holds pretty damn well. Not perfect, but no bubbling sounds.

    It's HIGHLY unlikely that it's the rings. There was only a 1-3 psi improvement with the wet comp test and I used plenty of oil on top of that it has newer pistons and rings

    one last thing (not trying to hound you) I didn't say I was burning any oil on idle. No smoke, exhaust smells "good".
     
    #11
  12. firefighter

    firefighter Proven Member

    DSM Profiles:
    1
    Joined:
    Sep 8, 2008
    Posts:
    77
    Likes Received:
    0
    amsterdam, New_York
    Cam has nothing to do with blowby.Your compression seems a little low. By any chance does your dip stick work itself out? if so you might have excess blow by.This is caused by worn rings. What you might want to check is your plumbing to your intrcooler.You might have oil in all the piping as well as your intercooler. What causes this is the vent tube coming from the valve cover to the intake hose having to much crank pressure. You can solve this problem by installing a catch can off of the valve cover. Depending on how much oil you use it might not be a big problem BUT you wil eventually need a ring job and if thats the case you might as well freshen up the whole engine..
     
    #12
  13. Benshooter

    Benshooter Proven Member

    Joined:
    Dec 9, 2009
    Posts:
    205
    Likes Received:
    3
    Las Vegas, Nevada
    I apreciatte everyones input and I'm not trying to be a dick but please read the entire thread. The rings are not the problem; this was deducted from a very minimal compression increase in the wet compression test.

    I have a simple valve cover breather filter on it. There's usually a little oil soaked in it but it has never been so saturated that it dripped or anything. My dipstick doesn't pop out but I pinched the tube slightly so it fits snuggly. My LICP has a verrry thin coat of oil along the bottom circumference of it, nothing too serious.
     
    #13
  14. LiquidX

    LiquidX DSM Wiseman

    Joined:
    Sep 19, 2008
    Posts:
    6,591
    Likes Received:
    79
    Anywhere, Pennsylvania
    My mistake, I thought I read idle in there as well.

    I did read the post entierly, that's why I edited one of my posts dealing with the idle. I stated that 10ish is low for stock but for aftermarket cams, depending on grind, is normal.
     
    #14
  15. firefighter

    firefighter Proven Member

    DSM Profiles:
    1
    Joined:
    Sep 8, 2008
    Posts:
    77
    Likes Received:
    0
    amsterdam, New_York
    Lets think about it, you have what you believe is to much pressure coming out the top of your valve cover. There are several thing that could cause this increase in pressure 1. rings 2. turbo 3. ventilation system not working properly. Start off by checking the vent system. You indacate that the breather has a little oil on it .Replace it run the engine see if that changes it, if not check the turbo I don't think that has anything to do with it. If the seals are bad you'll have oil leaks either internal or external.If it's external you'll just have a messy turbo If its internal thats very bad,again if its on the intake side you could do damage to the engine, if on the exhaust side you could have a engine fire.Just in case check your oil lines coming off your turbo. The last thing is your rings.If you did a wet test and compression went up that means you have a little bit of blow by .That could be causing a increase in your oil pan.Causing excess pressure coming out of the oil cap.
     
    #15
  16. BIRDCLAWTSi

    BIRDCLAWTSi Supporting Member

    DSM Profiles:
    1
    Joined:
    Apr 13, 2009
    Posts:
    502
    Likes Received:
    3
    Danbury, Connecticut
    do a leakdown test and see what is going on.that will put it to rest. or you can use a smoke machine. see where the smoke comes out.
     
    #16
  17. romeen

    romeen DSM Wiseman

    Joined:
    Jul 12, 2006
    Posts:
    2,434
    Likes Received:
    24
    Vancouver, Washington

    Agreed.:thumb:

    With the engine idling remove the oil cap (be prepared for it to spray a bit of oil) and place a piece of paper over the opening. It should look like it's rapidly bouncing up and down as the air alternately pushes out and pulls in. If compression checks out, boost leak test is good and car is running fine then I would say nothing to worry about.
     
    #17
  18. Benshooter

    Benshooter Proven Member

    Joined:
    Dec 9, 2009
    Posts:
    205
    Likes Received:
    3
    Las Vegas, Nevada
    I'm about to start pulling my hair out... :ohdamn:

    IT'S NOT THE RINGS. How about in Spanish? NO ES LOS ANILLOS!

    Cleaning or changing the breather filter isn't going to make a damn bit of difference. The oil cap blows the same with or without it. Think about it, that much air coming out of the oil cap which has roughly 10 times the area as the VC breather, the VC breather can't vent all that properly with or without a filter.

    Like I said, unless it's something way out in left field that I'm unaware of I pretty much have it narrowed down to the valvetrain but I need to know what exactly to look for within the valvetrain and how to test those components to see if or how they are malfunctioning. The only other problem I can think of is a headgasket that's leaking evenly (again, highly likely).

    I am aware that normally there is SOME air cycling in and out of the breather or oil cap neck when the cap is off, it usually feels like a light breath on your hand. This is due to the alternating crankcase pressure etc. The force with which the air is coming out of my oil cap neck is like someone forcefully blowing on to my hand.

    I think this might be the best idea i've heard so far. I have a good fogging machine for Halloween. How would I use it exactly? Put it by the intake and watch for any fog coming out of the oil cap/vc breather? Now that I think of it, this could be a great alternative for finding boost leaks, whether the system is pulling vacuum or is pressurized...

    Tip of the hat...
     
    #18
  19. firefighter

    firefighter Proven Member

    DSM Profiles:
    1
    Joined:
    Sep 8, 2008
    Posts:
    77
    Likes Received:
    0
    amsterdam, New_York
    Thats what I love about you guys. You ask for help but then you seem to have all the answers. why ask for advise. good luck to you.
     
    #19
  20. Benshooter

    Benshooter Proven Member

    Joined:
    Dec 9, 2009
    Posts:
    205
    Likes Received:
    3
    Las Vegas, Nevada
    No I don't have the answers and I come looking for help with a big slice of humble pie but I clearly stated, and RE-stated, it's not the rings. If they were bad I would have seen more than a mere 1-3 psi increase when performing the wet compression test. Make sense? I'm trying to be humble and nice but I don't like repeating myself and this isn't my first rodeo.

    Sorry if I offend but this isn't a generic problem/answer and I've already stated what the possible problems are and are not.
     
    #20
  21. this_tsi_8urV8

    this_tsi_8urV8 Proven Member

    Joined:
    Jul 13, 2004
    Posts:
    402
    Likes Received:
    1
    Chicago???, Illinois
    What are the results of the compression test?
    You are either getting too much blow by OR somehow too much or not enough air is leaving the crankcase.
    Connect the tranny side vent of vc back to intake pipe, make sure pcv is actually working and pref Mitsu(I remember reading you replaced it, but not sure with what), or you have a clogged line blocking air flow.
    When I connected my catchcans, I hooked them up wrong, and had them like that for A WHile and beating on it too, I went to wash the car and it was idling for a while and I saw some and I thought I messed up my recently rebuilt engine, got scared, turned off car and tried taking off oil cap, it was really hard to turn, bc of the pressure in the system, after cpl of min of pressure subsiding, I twisted off cap and you can hear the pressure. Turned on the car and there was smoke and pressure coming out of cap. And then I realized I had it connected wrong and was blocking the exit of the pressure from the vc. After I fixed it, car didn't smoke, and no more pressure in crankcase.
    Also, I had that same problem when my ring lands broke and my rings were fried.
     
    #21
  22. Benshooter

    Benshooter Proven Member

    Joined:
    Dec 9, 2009
    Posts:
    205
    Likes Received:
    3
    Las Vegas, Nevada
    121 126 125 128

    120 124 126 129

    120 125 127 130

    that's 1234 order

    wet:

    122 129 129 130.

    The PCV is OEM. I don't see what the difference would be in routing the vc breather to the intake mani but I'll give it a shot an see what happens.

    Was your catch can vented?
     
    #22
  23. LiquidX

    LiquidX DSM Wiseman

    Joined:
    Sep 19, 2008
    Posts:
    6,591
    Likes Received:
    79
    Anywhere, Pennsylvania
    Those numbers are VERY low. When did you have the rings done?

    Having the line hooked up to the intake will create a vacuum pull from the head removing the pressure in there better IMO. Also, even OEM PVC valves are bad and don't seal properly when there is positive pressure (went to the dealer and went through 8 PVC valves until I found one that sealed properly). Look into using one of these to as a back up for the PVC. I use one and it works great.
     
    #23
  24. Benshooter

    Benshooter Proven Member

    Joined:
    Dec 9, 2009
    Posts:
    205
    Likes Received:
    3
    Las Vegas, Nevada
    The numbers are definately crap, but service limit is 130 so I should be able to sneak by for a short time. When I bought the car he gave me a list of all the mods and work done and it supposedly had 5000 miles on it, which means it's at about 7k now. New pistons (.5mm oversize according to the paperwork). The kid was very honest and up front about anything I asked so I don't think he was lying to me about the miles on the rebuild. Plus, when I pulled the plugs out, I put a small video camera (normally for small plumbing application but works awesome for anything like this) down the spark plug holes and the pistons look brand new. All of this along with the wet test results are why Im pretty sure it's in the valvetrain.

    I tested the pcv with a rubber tipped air sprayer thing when I noticed the problem. Holds pressure fine and releases it all the same.

    I think it will definately help the pressure vent when the intake is at a vacuum, but what happens when I boost? Seems like it would make the problem worse and that's what I'm afraid of.
     
    #24
  25. BIRDCLAWTSi

    BIRDCLAWTSi Supporting Member

    DSM Profiles:
    1
    Joined:
    Apr 13, 2009
    Posts:
    502
    Likes Received:
    3
    Danbury, Connecticut
    if you can thread it into the sparkplug hole, maybe take the compression tester and remove the gauge, hook the line to it and go from there, you will have to put the engine at top dead center on the compression stroke for each cylinder. see where the smoke comes out, if any at all. tail pipe=exhaust valve,intake=intake valve,oil cap=rings,etc...i have a smoke machine for evap leaks at work and that is how i did it without a leakdown tester. good luck
     
    #25

Share This Page