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Thread: Internal Oil Leak

  1. #1
    Join Date
    Sep 2016
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    2002 325Ci Convertible

    Internal Oil Leak

    2002 325ci convertible 231,000 miles. I recently had my car at the dealership to repair the top. I told them that I was using a quart a week in oil and asked them to check for an oil leak and to also check the PCV value and oil separator. They said that they could find anything externally but suggested that I might have an internal oil leak (what ever that means).

    I am already using Lucas oil treatment but does not seem to be helping with the oil consumption. Are there any other type of additives that I should use to cut down on oil usage?

  2. #2
    Join Date
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    Internal oil leak would be caused by worn rings or valve guides. Your next step should be a leak down test and compression test. That will give you a pretty good idea of the internal health of the engine. If you get good results from those tests you probably need to replace the oil separator. If the diaphram inside the separator fails it can cause high oil consumption like yours. I'm not aware of any way to test that separator but there might be. Usually if your CCV system has anything close to 100,000 miles on it you should just replace it before the plastic tubes break.

  3. #3
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    Wouldnt it be great if they could explain that to you. Second above comment

  4. #4
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    Thank you for responding. What is a leak down test?

  5. #5
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    You put each cylinder at top dead center with the valves closed inject air pressure in the the combustion chamber via the spark plug hole and the gauge attach to the line that's threaded into the spark plug hole will measure the amount of air leaking past the piston rings or valves, so low numbers good say 10% or below good, higher numbers bad.

  6. #6
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    I honestly don't believe your engine is toast. I think it's the CCV system but a leak down test should be done first just to confirm. Diagnostics are much cheaper than blindly throwing parts at an issue. That's a deep rabbit hole you don't want to go down. It's probably a failed separator or a clogged CCV drain tube. Both a very common issues and both will easily cause excessive oil consumption.

  7. #7
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    Really you need to do top up the oil write down the date and mileage, the the next time you need oil see how many miles it took to use the oil

  8. #8
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    I should also mentioned that I occasionally pass some smoke in first gear after coming to a stop or sitting at a traffic light. I do not have any smoke when I start the car.

  9. #9
    Join Date
    Mar 2017
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    Norwich, Connecticut.
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    E46 wag. E36 convertible
    You have 231k...that's a lot of engine and drive train time. At this stage, all gaskets... including front-rear engine main seals, transmission forward and tailshaft..rear diff not so much but an inspection for sure, are near end.... I'm mentioning vitals...others include a 2 cam valve cover (if in-line) and oil filter body housing, and a few more more unlikely. 231k ....Everything is on the table unless you have a tabulated history with time lines for next service..(meaning important items were serviced along the way) .For example, what is the integrity of your DC alternator now..at 231k? .....Replacing the alternator involves a lengthy procedure and it's costly if you don't replace it yourself...At 231k, I would replace the alternator, not just put a new regulator in...I'd suspect the cooling system has had attention but does the original radiator still flow as was when new?..................This is the time when in the past I have decided to NOT spend more money or time on it...but cut and chase...and find another!.........good luck guy
    Last edited by Eaglesail; 09-12-2017 at 04:31 PM.

  10. #10
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    jclausen, my commute is about 100 miles per week. Round trip to work is 8 miles. On Monday nights I have band practice, 50 miles round trip and then some local weekend driving.

  11. #11
    Join Date
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    Bellevue, WA
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    335d, 328xd (had 330xi)
    The M54 engines are notorious for using oil. As mentioned, some sort of leak due to wear is the probably cause. Probably your valve stem seals.

    If it's not more than a quart every 1200-1500 miles, just keep topping it off.

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