Positive crankcase pressure at idle.

Discussion in 'OT Driven' started by deusexaethera, May 14, 2008.

  1. deusexaethera

    deusexaethera OT Supporter

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    Technically this applies to a Volkswagen, but you guys seem to know more about the inner workings of engines than do the import guys.

    I've been having trouble with multiple oil leaks lately. Now, as far as I know, if the PCV system were providing adequate vaccuum to the crankcase, even if seals were leaking they would at least be letting air in instead of letting oil out (until the engine shuts off, at least). But there are two problems with that:

    1. I rebuilt the PCV system myself a few months ago, and I know it's providing adequate vaccuum.

    2. When I pull the dipstick out while the engine is still running, I can see a stream of thin smoke blowing out -- not drifting, not wafting, blowing out.

    So, there's positive pressure in the crankcase, and the PCV system isn't moving enough air to compensate. My engine is turbocharged, but that shouldn't make a difference at idle because the turbo isn't spooling at idle (and the PCV valves are there specifically to keep turbo pressure from making its way into the crankcase, anyway). So something is applying pressure to the inside of the crankcase, even at idle. The only thing I can think of that has high pressure at idle is the insides of the combustion chambers.

    Does this sound like bad rings to you guys too? 'Cause it sounds like it to me.
     
  2. mikeflys1

    mikeflys1 New Member

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    yes
     
  3. art_VW_shark

    art_VW_shark OT Supporter

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    dude your Vdub is so fucked :(
     
  4. Mjolnir

    Mjolnir WHM6D > *

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    Put an LS1 in it. That's the only answer.
     
  5. Bugalu

    Bugalu OT Supporter

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  6. deusexaethera

    deusexaethera OT Supporter

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    Hah! I was just thinking the other day how funny it would be to put an LS1 in it. It's got a longitudinal engine and everything, so the only real issue would be whether the engine bay is big enough. There's that W8 engine that fits, but I don't know how much shorter the W pattern makes it compared to a V.

    Seriously, though, goddamnit. My old Mazda didn't have blowby until it was 14 years old.
     
  7. deusexaethera

    deusexaethera OT Supporter

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    Three words, buddy, three words: USE SYNTHETIC OIL.

    Well...actually, the prior owners' choice of lubricants probably has nothing to do with my bad rings, but that little turbo gets so bleeding hot it'll burn cheap oil to a crisp. Literally.
     
  8. Mjolnir

    Mjolnir WHM6D > *

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    I know this is a cxompletely dick thing to do, but why not make it someone else's problem?
     
  9. deusexaethera

    deusexaethera OT Supporter

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    I've modified the car. Dealers won't give me shit for it. The only buyers I could sell it to would be other enthusiasts (such as the word "enthusiast" can apply to a would-be Passat driver).
     
  10. Mjolnir

    Mjolnir WHM6D > *

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    rock <> deusex <> hard place
     
  11. deusexaethera

    deusexaethera OT Supporter

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    Heh...yeah, I guess. The car is a classic example of a money pit -- for $25k I can get a new car, or for a few hundred I can fix the latest in a series of problems, each slightly more expensive but easy enough to justify when you consider the money I've already invested in fixing it. Pretty soon, I'd spent enough that I could've made a substantial down-payment on that new car. Oh well, live and learn.

    The thing still drives well, it just sprays oil out of every possible location -- including the oil cap, because VW engineers thought a screw-on oil cap was too "old-school" and they just knew they could make a better one. :rolleyes:

    Anyway, I might as well assess how bad it is. Does anyone know where I can get a compression tester, along with a decent explanation of how to use one? I'm bound to need it again, someday.
     
  12. P07r0457

    P07r0457 New Member

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    Volkswagen is the pinnacle of excellence few automakers can match or even comprehend for that matter. Domestics have shoddy engineering with unacceptable levels of extra millimeters between interior panels. My Passat does every thing and it does it stylishly. When people ask me what the culmination of intensive research and design is only one word comes to mind: Passat.

    When people ask me what the answer is to the fuel mileage problem the answer is clearly Diesel. And of course it is Volkswagen there at the ready delivering diesel technology.

    Who may you ask dominates Le Mans with Diesel? That's right bitch, Audi. And in case you didn't know, Volkswagen and Audi are the same thing, the same great excellence freight train.

    I am constantly bombarded by you fools who have no understanding of global economics and the automotive industry. I deusexaethera am a lone wolf and perhaps the only person on these boards that can completely understand what a car is and does. None of you know what you are talking about primarily because you don't have enough logic to do the right thing and get a Passat.

    But that is perfectly fine I like being the only Passat on that road at night, coasting (most comfortably mind you) at a cool 90+mph with excellent stability.

    I am basically a master mind of all things car related and none come even close to bringing to the table the same knowledge that I do each and every day in OT Driven.
     
  13. deusexaethera

    deusexaethera OT Supporter

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    (sigh)

    You forgot the quotes this time.
     
  14. art_VW_shark

    art_VW_shark OT Supporter

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    we've been using the Vdub synthetic. lol my dad does all maintenance at dealer. :mamoru::mamoru::mamoru: not my dime. speaking of which, my good ol' b5.5 is due for a oil change soon. and an alignment. and it's still poor on fuel, but none of the dealers, surprise surprise, have been able to pin that to a particular problem.


    car runs like a fucking CHAMP other than aforementioned problems. :bowdown::bowdown::bowdown: 7 year old VW, in a month
     
  15. sleepyhead

    sleepyhead New Member

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    you can pretty much pick up a compression tester anywhere. Harbor freight even has them now, there's nothing too complicated about them.

    1. Warm the car up a bit.
    2. unplug the individual fuel injectors if you can, or take out the fuel pump fuse and run the car, so you de-pressurize the fuel system.
    3. Remove the spark plug from 1 cylinder.
    4. screw in the compression tester
    5. Crank the engine 5-10 times or until the gauge stops rising. Make sure you hold the throttle open.
    6. Read the number, reset the gauge, replace the spark plug and move onto the next cylinder.
    In a nut shell that's it.
     
  16. deusexaethera

    deusexaethera OT Supporter

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    Ah, so that's how it works. That'll do, thanks.
     
  17. PanzerAce

    PanzerAce Active Member

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    the key, however, is to complete the SAME amount of cranks for each cylinder :o. yes, it can change it.
     
  18. deusexaethera

    deusexaethera OT Supporter

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    Ah fuck, why'd you have to bring that up? Can't I just crank it for 15 seconds per cylinder, or something similar where the peak pressure should be reached long before I stop cranking?
     
  19. mikeflys1

    mikeflys1 New Member

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    The method listed above is the way i've always done it except i remove all the plugs. You should get about half of the total reading in the first 2 cranks and it really doesnt matter if you crank exactly the same on all cylinders...the gauge just holds peak pressure so its not gonna change really past 5-6 cranks. In your case getting an exact reading probably wont matter anyways...it sounds like its gonna be pretty obvious which cylinder(s) arent holding pressure.
     
    Last edited: May 16, 2008
  20. PanzerAce

    PanzerAce Active Member

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    Long as the time/revs are the same when you test each cylinder, should be fine.
     
  21. deusexaethera

    deusexaethera OT Supporter

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    Good enough then. Now I just gotta buy one.

    Thank god I have a fourbanger; the V6 in my dad's old van could probably use a test like this, but the sparkplugs are halfway down the engine bay. Might are right at the top.

    You know, now that I think about it, I had a compression test done back in '06, and the numbers were all between 175-180psi, right on target. So either the rings don't like 18psi of boost, or I shouldn't have driven the thing 75 miles on three cylinders that one time when the ignition controller went to shit. :hs:

    (it was either that, or camp out in a parking lot in the middle of God's country all night.)
     
    Last edited: May 16, 2008
  22. PanzerAce

    PanzerAce Active Member

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    three cylinders shouldn't have fucked up the ring. It's probably the PSI that it didn't like.
     
  23. deusexaethera

    deusexaethera OT Supporter

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    Well, the problem is (and I wish I'd thought of this at the time) the fuel injector was still spraying gas into the cold cylinder the whole time, diluting the oil on the cylinder walls. I should've unplugged the fuel injector before driving it, but I was a car noob at that point.

    That's one thing I can say about this car, I learned quite a bit about how it takes care of its business.
     
  24. Mjolnir

    Mjolnir WHM6D > *

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    Silver lining.

    I had a mid 80's Buick when I was going to tech school that I'd always try new shit on after I learned it. By the time I graduated it had new ball joints, new half shafts, a rebuilt tranny, and multiple "repairs" that were the result of me taking shit apart and figuring out how it went back together or stuff that broke after I "improved" it.

    Good times, aren't they?
     
  25. deusexaethera

    deusexaethera OT Supporter

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    Well, it's not the rings, fuck have it all. The acceptable range is 150-190psi on a new engine, and my numbers follow:

    190
    192
    210 (!)
    180

    I cranked for ten seconds apiece, to be sure I got a good reading. The engine literally couldn't be better if it were new.

    So where the fuck is the crankcase pressure coming from??
     

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