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Thread: Oil Filler cap trick?

  1. #1
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    Oil Filler cap trick?

    First off, any help or advice given is greatly appreciated. I recently bought a 2002 325ci, the SES light came on the first day I got it (go figure), so I took it to Advance to get the codes read. I got the following codes P0313, P0300, P1344, P1346, P1083, P1085, P0174, P0171, P1350 lol. From what I have gathered they are mostly misfire, and lean mixture codes. The guy at advance suggested that I change my 02 sensors, but from reading here I learned of, and tried the "oil [COLOR=blue! important][COLOR=blue! important]filler [COLOR=blue! important]cap[/COLOR][/COLOR][/COLOR] suction trick". I read in here that if you start your [COLOR=blue! important][COLOR=blue! important]car[/COLOR][/COLOR], let it idle, slowly remove the oil filler [COLOR=blue! important][COLOR=blue! important]cap[/COLOR][/COLOR] and detect alot of suction, and car stumbles slightly then you have a bad PCV valve. I tried that and had a pretty strong suction. So I am assuming that is the problem. However, I tried showing it to a friend and the second time I did it, it smoked pretty bad for a few minutes. I drove it around for a few, and the smoke went away but it really concerns me. does anyone have any experience or suggestion with this? Again thanks for any advice or help.

  2. #2
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    See answered post in other thread.
    Quote Originally Posted by B4SH View Post
    If anyone knows, it's this guy who knows literally nothing about everything.
    Quote Originally Posted by fcvapor05 View Post
    Do you even OT? The mean 401k around here is probably about $6, what with all the shiny cars and $1,000 watches and donations to get other members' Volvos running.


  3. #3
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    We have seen a few cylinders filling with oil when the PCV goes, 2 in the last week. If the conditon worsens the car won't start and you will need to evacuate the oil out of the cylinders. Autozone codes are pretty worthless and even the GT-1 isn't the best diagnostic tool for this situatin. Removing the cap is actually the best test and if the cap is really hard to remove right after start-up and there is a loud sucking noise its probably the PCV.

  4. #4
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    Critter: which other post? Can't find it...

    Chris Powell
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  5. #5
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    Hm I thought my PCV was bad but nothing happens when I take out my dipstick.

  6. #6
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    The best test for a failed CCV is to check the crankcase pressure with the engine idling. If the CCV is operating properly the pressure will be 3-6" of water.

    Hm I thought my PCV was bad but nothing happens when I take out my dipstick.
    If nothing happens when you remove the oil filler cap, the CCV is completely plugged or there's a large intake leak. When everything is right, removing the oil filler cap causes an intake leak and the engine will change speed and run a bit rough.
    The car makes it possible, but the driver makes it happen.
    Jim Levie, Huntsville, AL

  7. #7
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    Quote Originally Posted by bmwdirtracer View Post
    Critter: which other post? Can't find it...
    I'll see if I can find it... this was posted in some other forum, worded nearly identically, although I don't know if it's the same OP.


    Quote Originally Posted by Mototryph View Post
    First off, any help or advice given is greatly appreciated. I recently bought a 2002 325ci, the SES light came on the first day I got it (go figure), so I took it to Advance to get the codes read. I got the following codes P0313, P0300, P1344, P1346, P1083, P1085, P0174, P0171, P1350 lol. From what I have gathered they are mostly misfire, and lean mixture codes. The guy at advance suggested that I change my 02 sensors, but from reading here I learned of, and tried the "oil filler cap suction trick". I read in here that if you start your car, let it idle, slowly remove the oil filler cap and detect alot of suction and car stumbles slightly then you have a bad PCV valve. I tried that and had a pretty strong suction. So I am assuming that is the problem. However, I tried showing it to a friend and the second time I did it, it smoked pretty bad for a few minutes. I drove it around for a few, and the smoke went away but it really concerns me. does anyone have any experience or suggestion with this? Again thanks for any advice or help.
    And I told him that this is what's supposed to happen when you take off the oil filler cap and it may even set the check engine light.

    Quote Originally Posted by thejlevie View Post
    The best test for a failed CCV is to check the crankcase pressure with the engine idling. If the CCV is operating properly the pressure will be 3-6" of water.


    If NOTHING happens when you remove the oil filler cap, the CCV is completely plugged or there's a large intake leak. When everything is right, removing the oil filler cap causes an intake leak and the engine will change speed and run a bit rough.

    I didn't know this was the case, but we should be shouting this from the rooftops, because if I read another person write that they "tried taking their oil cap off and their engine stumbled so they replaced their CCV and it didn't change anything", I might just scream.
    Quote Originally Posted by B4SH View Post
    If anyone knows, it's this guy who knows literally nothing about everything.
    Quote Originally Posted by fcvapor05 View Post
    Do you even OT? The mean 401k around here is probably about $6, what with all the shiny cars and $1,000 watches and donations to get other members' Volvos running.


  8. #8
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    The previously mentioned slack tube is the best indicator, but not everyone has access to that. My main concern is that we have been seeing more than just CEL's we've been seeing damage. Like window regulators these cyclone valves will eventually fail.

  9. #9
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    The CCV has a finite life. At some point the internal diaphragm will fail and there will be idle problems and excessive oil consumption. The only reliable diagnostic is the crank case pressure check.
    The car makes it possible, but the driver makes it happen.
    Jim Levie, Huntsville, AL

  10. #10
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    Thank you, Jim and Critter. I really don't understand how the basic diagnostic aid of pulling the filler cap got turned so completely backwards as to indicate the opposite!

    Do either of you fine gentlemen have knowledge of BMW V12 specific vacuum system differences? I seem to recall my "factory" training denoted some such item, but a fellow BMW guy and master tech says the V12's "have no vacuum", which makes no sense to me.

    Chris Powell
    Racer and Instructor since, well. decades, ok?
    Master Auto Tech, owner of German Motors of Aberdeen
    BMWCCA 274412
    German Motors is hiring ! https://www.bimmerforums.com/forum/s...1#post30831471

  11. #11
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    Sorry, but I can't be of help w/respect to V12's.
    The car makes it possible, but the driver makes it happen.
    Jim Levie, Huntsville, AL

  12. #12
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    I guess the thing I am most concerned with, is that when I took the oil cap off the second time it smoked really bad after I put it back on. Is that normal, does anyone know what might have caused that? It hasnt smoked since, but it let quite a bit of smoke out when it first happend. I guess I shoul have worded my original post a little different.

  13. #13
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    The smoke may be just another symptom of a bad CCV. When you took the cap off the flow of air through the crank case increased and that pulled oil up into the intake.
    The car makes it possible, but the driver makes it happen.
    Jim Levie, Huntsville, AL

  14. #14
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    Well its being serviced right now, the dealer I bought it from is taking care of everything for me, so thats cool of them. I spoke to the mechanic, and he said he did a smoke test on it, found out it has a leak and he is going to fix it. Could the fact that it has other leaks be causing the high suction, when I removed the oil cap? He said it is leaking from somewhere under the intake. Im not as mechanically inclined as most of you, so please excuse the questions. Just paranoid, and really hate having lights on in my car. Again, any help is appreciated.

  15. #15
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    Quote Originally Posted by bmwdirtracer View Post
    Thank you, Jim and Critter. I really don't understand how the basic diagnostic aid of pulling the filler cap got turned so completely backwards as to indicate the opposite!

    Do either of you fine gentlemen have knowledge of BMW V12 specific vacuum system differences? I seem to recall my "factory" training denoted some such item, but a fellow BMW guy and master tech says the V12's "have no vacuum", which makes no sense to me.

    Well...the current V8's don't produce any vaccuum because they have Valvetronic... and if the current V12s are Valvetronic, then they don't create any either. I'll try to recount exactly why... the current Valvetronic cars don't use a conventional throttle butterfly to regulate the amount of air going into the engine, they use differing amounts of valve lift. i.e. at idle the intake valves only open up .2mm (or something tiny like that, I don't know the exact number), but at full throttle, they open up, say, 1.5mm (again, example number). Now.... normal engines create vaccuum because the valves always open the same amount and are trying to suck in the same (very large) amount of air per piston stroke, but the throttle butterfly holds it back and voila! we've created engine vaccuum. In normal driving, the Valvetronic engine's throttle butterfly is held wide open (only to be used as a backup if the Valvetronic fails) so there is flow, but there's vaccuum only in the cylinder itself, so the Valvetronic engines actually have a vaccuum pump on the front of the engine to create vaccuum for the engine to use for CCV and braking and whatever else uses vaccuum.

    Sorry for the novel....

    Quote Originally Posted by thejlevie View Post
    The CCV has a finite life. At some point the internal diaphragm will fail and there will be idle problems and excessive oil consumption. The only reliable diagnostic is the crank case pressure check.

    We had a discussion about these failing CCVs just this morning. We've come to the (unofficial) conclusion that when the Federal Gov't required the banishment of MTBE usage in fuel and the oil companies started using ethanol instead, is about the same time we started seeing problems with the CCVs freezing due to condensation issues. Prior to about 2005, we never saw a X5 3.0 come in with a frozen CCV, much less a hydrolocked engine from oil ingestion.

    Our theory is that ethanol produces extra water vapor during combustion and (especially in cars that don't drive 20 miles every time they're started up) that extra water vapor ends up causing the oil to foam, fills the CCV and then the water content in the frothy oil freezes when the car is shut off.

    Discuss.
    Last edited by Critter7r; 01-28-2009 at 12:59 PM. Reason: Automerged Doublepost
    Quote Originally Posted by B4SH View Post
    If anyone knows, it's this guy who knows literally nothing about everything.
    Quote Originally Posted by fcvapor05 View Post
    Do you even OT? The mean 401k around here is probably about $6, what with all the shiny cars and $1,000 watches and donations to get other members' Volvos running.


  16. #16
    hooRAH is offline Certified Ziptie Mechanic
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    Quote Originally Posted by Critter7r View Post
    Our theory is that ethanol produces extra water vapor during combustion and (especially in cars that don't drive 20 miles every time they're started up) that extra water vapor ends up causing the oil to foam, fills the CCV and then the water content in the frothy oil freezes when the car is shut off.

    Discuss.
    Clever theory. I don't know if I would venture to guess that the oil would foam more, as I think you'd see a lot of mis-diagnosed "head gaskets" out there for foam on the dipstick, and I'd think you'd see evidence of that when you pulled the CCV out.

    Still, it may be possible that the extra water vapor in general is suspended in the oil, and makes its way to the CCV with the rest of the oil, and freezes in the CCV.

    I really don't feel like replacing my CCV, but I think its next on the list.

    BTW, OP, congrats on getting the dealer to take care of the problems - when I first saw that list of codes, after 1 day of driving, I thought "Man, this guy got suckered".

    Then, when I realized that you bought it from a dealership, while good that they agreed to fix the problems, I think its pretty obvious that they cleared the OBDII system and put it out on the lot, which is a bit shady.
    01 330Ci 5spd / 07 Honda Pilot EX-L
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  17. #17
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    SO if its not the CCV (my oil is ok) then what would cause the leak. Manifold gasket?

  18. #18
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    We had a discussion about these failing CCVs just this morning. We've come to the (unofficial) conclusion that when the Federal Gov't required the banishment of MTBE usage in fuel and the oil companies started using ethanol instead, is about the same time we started seeing problems with the CCVs freezing due to condensation issues. Prior to about 2005, we never saw a X5 3.0 come in with a frozen CCV, much less a hydrolocked engine from oil ingestion.

    Our theory is that ethanol produces extra water vapor during combustion and (especially in cars that don't drive 20 miles every time they're started up) that extra water vapor ends up causing the oil to foam, fills the CCV and then the water content in the frothy oil freezes when the car is shut off.
    That's an interesting theory. But I wonder it it has more to do with which engine is involved and when that engine was generally available in an X5.
    The car makes it possible, but the driver makes it happen.
    Jim Levie, Huntsville, AL

  19. #19
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    Quote Originally Posted by hooRAH View Post
    Clever theory. I don't know if I would venture to guess that the oil would foam more, as I think you'd see a lot of mis-diagnosed "head gaskets" out there for foam on the dipstick, and I'd think you'd see evidence of that when you pulled the CCV out.
    Here's the funny part (funny weird, not funny haha): the oil doesn't really do any foam-ing in the oil pan, a little foam gets onto the bottom of the dipstick but only because it gets sent there from the CCV and down the guide tube to get back to the oil pan.

    It's the CCV that causes the foaming. The CCV has a diaphram inside and that diaphram tends to vibrate while the engine is running. So imagine a thin rubber diaphram vibrating a mixture of oil and water and voila! instant foam. Then that foam starts to make its way back down the guide tube for the dipstick (on its way to the oil pan) when the engine is shut off in 5 degree weather. You can imagine oily foam not travelling very fast down a 1/2-inch diameter tube and the water suspended in the oily mixture freezes, holding the foam in place. The car sits long enough and it freezes solid, so the next time the car starts BAM! smokin out the tailpipe and the valve cover gasket blows off from the pressure.

    Quote Originally Posted by thejlevie View Post
    That's an interesting theory. But I wonder it it has more to do with which engine is involved and when that engine was generally available in an X5.
    It's the 3.0 M54 engine that has that problem. It's been available since the beginning of E53 X5 production.
    Quote Originally Posted by B4SH View Post
    If anyone knows, it's this guy who knows literally nothing about everything.
    Quote Originally Posted by fcvapor05 View Post
    Do you even OT? The mean 401k around here is probably about $6, what with all the shiny cars and $1,000 watches and donations to get other members' Volvos running.


  20. #20
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    Well, for people who read this for ruture refrence. I spoke to my mechanic today, and he ended up replacing the PCV valve, and some vacum hoses. I should be getting it back this afternoon, so I will let you guys know if any lights come back on. I never mentioned anything I read in the forums here to my mechanic, but he explained to me the exactly the things I have read, so it is comforting to know that he is doing exactly what you guys suggested. I appreciate all of your help, and for the guys who took the time to write up those DIY forums... You are the shit. I will let you all know what happens.

  21. #21
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    I just replaced my valve cover gaskets. Leaking really badly. The spark plug wells were filled up so much that I could just make out the top of the spark plug.

    New gasket, oil removed from spark plug wells, and all is well.

    I have a 2001 X5 with the 3.0. The best I can tell, I don't have a PCV, but do have the Oil Separator. Is the Oil Separator the CCV your refrencing? From the diagrams I have seen, the Oil Separator is a vaccum device with 4 hoses running to/from it. I live in Michigan, and we in the North have been subject to some pretty cold temps lately.

    Does the separator need replacing? Best diagnostic trick for it?

    Side note.. From day one, this car has used oil. 1 qt. every 1100-1300 miles. Could the separator be apart of the oil consumption? (I don't see smoke from the tail pipe)

  22. #22
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    Critter, thanks so much for valvetronic lesson, I'd never realized the repercussions from the system vis-a-vis the engine's vacuum and intake.

    MJFX, smoke test the system.

    Chris Powell
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    Master Auto Tech, owner of German Motors of Aberdeen
    BMWCCA 274412
    German Motors is hiring ! https://www.bimmerforums.com/forum/s...1#post30831471

  23. #23
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    soo, what happend? lol my friend's car is throwing the same codes and curious to know what the problem was.

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