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Thread: Venting the M54 Crankcase to the Atmosphere

  1. #1
    Join Date
    Feb 2018
    Location
    St Louis, MO USA
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    6
    My Cars
    1995 M3

    Venting the M54 Crankcase to the Atmosphere

    Let me start by saying I've read a ton of posts on M54 oil consumption and having built a couple engines so I am familiar with the concept of piston rings.

    My newly acquired 2005 X3 with a 2.5L M54 was guzzling a quart of oil every 150 miles. That's right. I got ripped off. Oh well. No white smoke from the exhaust. None. No leaks or drips. Not even a drop. It's a new-to-me vehicle with 100K miles that may have been neglected. As a way of troubleshooting I completely bypassed the CCV. Blocked everything off and vented the crankcase to the atmosphere. With no crankcase vacuum a fair amount of white smoke now whisps from the crankcase vent port. Engine still uses the exact same amount of oil. One quart every 150 miles. I have two explanations for this: 1. CCV was fine but I have worn or coked oil control rings; 2. By some strange coincidence the amount of oil an M54 without crankcase vacuum consumes is the same as that of one with a bad CCV.

    After bypassing the CCV and not getting the results I had hoped for I read a ton more posts. I then suspected that I could have coked oil control rings but still good compression. That's a valid condition on these engines, right? Well I tried Marvel Mystery Oil and Seafoam treatment in the crankcase to no avail. After two quarts of Marvel and two oil changes and two quarts of Seafoam and two more oil changes consumption is the same.

    Thoughts? Is there a logical next step to diagnose before throwing in the towel and assuming the oil control rings are toast? Compression test? Engine is peppy and like I said no smoke out the back.

    As an owner of a 2004 E46 325 I granted myself permission to post in the this forum for this issue instead of the X3 forum thinking I'd get a better answer here.

    Thanks for your help.

  2. #2
    Join Date
    Jul 2011
    Location
    Arlington, VA
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    5,472
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    2018 BMW M240i
    The M54 crankcase needs to be under a vacuum or else it’ll burn oil. That’s what the CCV is supposed to provide-vacuum. The CCV was designed by an engineer fired by Audi (imho)! So, bite the bullet and install a new OEM CCV. See if that reduces the oil consumption. If it doesn’t, your next step is to buy GM Top End cleaner from amazon. Then go to E46Fanatics and search for threads on the top end soaking process. If the engine still burns oil you can install an oil catch can. The can will provide even vacuum.

    Also double check for lesks at the oil filter housing. The M54 is notorious for leaking there. A new gasket is less than $10.

  3. #3
    Join Date
    May 2017
    Location
    Owings, Md
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    1996 328i
    Pardon my intrusion but I saw this under the new posts and had to look. I had a Lexus RX 300 develop the same kind of oil consumption around 200k miles (no history of abuse) from coked up rings. I was able to get them free by soaking with seafoam straight in the cylinders. It will work best to lift the passenger side up to help bring the block a little closer to level. Drain the oil out and leave the plug out of the pan so you can see how quickly the detergent is flowing past each cylinder, a compression test beforehand will certainly identify the worst. Manually work the crank shaft back and forth to help free up the rings and keep adding seafoam until the the rings can slow down the flow. I let it sit overnight and cranked it over in the morning with the plugs out and rags to catch the spray. I didn't think to pull my O2 sensors but they were fine. This is a pretty aggressive treatment and it may dislodge big chunks of carbon that could cause other problems but I looked at it from the pespective that the engine is basically done and it was worth the risk. My compression returned to within spec and I kept at it with the crankcase treatments like you have already done and I got another 70k miles out of the car till I sold it.

  4. #4
    Join Date
    Jul 2011
    Location
    Arlington, VA
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    The pros over at E46Fanatics use GM Top End cleaner. It’s very strong stuff.

    https://www.amazon.com/Genuine-88861.../dp/B00BK7LR36

  5. #5
    Join Date
    Feb 2018
    Location
    St Louis, MO USA
    Posts
    6
    My Cars
    1995 M3
    Thank you for the helpful comments. I've order two bottles of X66P and will report back.

  6. #6
    Join Date
    Mar 2017
    Location
    Norwich, Connecticut.
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    335
    My Cars
    E46,MB,Volvo,Audi,MG..
    Custom VENTING for ccv ....requires custom metal fabrication....Doing so, may void many 'state' emissions inspections.....It may not pass emissions...if you alter....just saying....

  7. #7
    Join Date
    Feb 2018
    Location
    St Louis, MO USA
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    6
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    1995 M3
    Update: I jacked the X3 pretty high to get the pistons to sit almost straight up and down. Did two soaks with B12 and one soak with GM Delco X66 Top End Cleaner. Effing miracle. Engine went from using a quart every 150 miles to no detectable use in 200 miles. It must have freed up a stuck ring. Very pleased.

    Thank you Marco Zandrini!

  8. #8
    Join Date
    Mar 2017
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    Norwich, Connecticut.
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    E46,MB,Volvo,Audi,MG..
    Yes: now all well and fine....but wait a minute...report back in 5k.....Seriously!

    Your posting here has raised an alarm for any M54.

  9. #9
    Join Date
    Jul 2011
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    Arlington, VA
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    2018 BMW M240i
    You’re welcome!! Also, try Shell Rotella 6 oil. People at E46Fanatics swear by this oil for their M54 engines. This oil is widely available. Try Walmart.

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