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  1. #1
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    Tracking Source of Intermittent Smoke from Exhaust

    Hey guys,

    I've done a bunch of research on this since it started happening and I haven't been able to find someone who describes a symptom similar to mine. So now I reach out to the community in hopes of finding a solution


    Here's what happens, randomly:
    Cold start the car and let it warm up, just sitting there idling till the revs come down. Pull out from driveway and start driving, no smoke at all, no smell. I get to the first stoplight on my way and Im sitting at the light, start to smell a nasty smell, something burning but Im not sure what. When I take off from the light (light to medium throttle input), a cloud of white smoke comes out of the exhaust. As I continue to accelerate, smoke goes away. If I happen to hit another light rather soon and have to stop, then more smoke comes out upon acceleration (less than first time tho). If I dont hit any light and just keep driving (i.e. get on freeway) and the car gets to full operating temp, then the smoke and smell will not come back, no matter how long I let it idle.

    As a test, I started my car one morning and let it continue idling after the revs came down. After about 5min, I could smell the nasty smell and I could see a very light smoke was coming from the exhaust and starting to fill the parking garage. I gave it some throttle input and a bunch of smoke came out and then clear. After that I shut the car off.

    Like I said, this happens randomly. It doesn't happen every time I start the car when its cold.


    My guess: Leaking injector? But does a leaking injector make a really nasty smell? Its not the smell of unburnt fuel or the normal catless smell. It is something distinct and pungent.

    Any thoughts, help, opinions are greatly appreciated.

    Thanks guys!
    Mike
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    460whp/510wtq tuned by Terry

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    Sounds like valve stem seals to me.

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    Hey @E90Company

    Do you have any related links where I could learn more about that? This is the first time I've seen the valve stem seals mentioned. Is it something that can be serviced?
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    460whp/510wtq tuned by Terry

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    I'm at the airport right now so unfortunately I don't have any DIY's or anything I can link, but a valve stem seal job is a bit extensive and costly if someone does it, but it can be serviced and will fix the problem. Your description sounds like that's what it is most likely. What happens is oil leaks past the seals because they are worn out, and some will go straight into the cylinders and burn off. How many miles do you have on the car?

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    I would of said valve stem seals as well but how do you explain that it doesn't happen all the time? And oil usually has a black/blueish color when it burns, not white. Has your coolant level gone down? What about oil?

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    1 out of 1 members liked this post. Yes Reputation No
    I had leaking valve stems. First are you fully catless or not? When I had my stock dp's in i would get little smoke as you explained, but when I went catless I noticed it a $#@!load (every time I came to a stop or even at idle).



    If it looks similar to the video I'd say you have valve stem leakage, if its very brief/ dosen't happen everyday its prob turbo seals. Mine smoke a tiny bit every now and then.

    What year car?
    08 328i, totaled by women driver
    07 335i, lots of mods.
    Now- 14 Focus ST
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  7. #7
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    Click here to enlarge Originally Posted by Alex325i Click here to enlarge
    And oil usually has a black/blueish color when it burns, not white.
    This is a misconception. I depends on where the oil is burning. If it is burning in the cylinder, then yes, blueish smoke is common. But if unburnt oil gets into the exhaust, the smoke can be white.

    I told a garage full of techs that my car was smoking because if a bad turbo letting oil into the exhaust. On of the less illustrious of the group tried to tell me I was burning coolant not oil because the smoke was white. I wasn't going to argue about the finer points of engine diagnosis with a bunch of car techs I don't know so I just said, "Maybe". Once I pulled it apart it was apparent the tech was wrong. White smoke can be caused by oil.
    Eppur si muove.

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    Click here to enlarge Originally Posted by E90Company Click here to enlarge
    I'm at the airport right now so unfortunately I don't have any DIY's or anything I can link, but a valve stem seal job is a bit extensive and costly if someone does it, but it can be serviced and will fix the problem. Your description sounds like that's what it is most likely. What happens is oil leaks past the seals because they are worn out, and some will go straight into the cylinders and burn off. How many miles do you have on the car?
    Got just over 60k miles on the car. It is a 2007.


    Click here to enlarge Originally Posted by Alex325i Click here to enlarge
    I would of said valve stem seals as well but how do you explain that it doesn't happen all the time? And oil usually has a black/blueish color when it burns, not white. Has your coolant level gone down? What about oil?
    Maybe it only happens when cold because once it is warm the seals dont leak anymore? Coolant level has not gone down. Oil level says it is at max every time I check it. Click here to enlarge


    Click here to enlarge Originally Posted by mikolo-n54 Click here to enlarge
    I had leaking valve stems. First are you fully catless or not? When I had my stock dp's in i would get little smoke as you explained, but when I went catless I noticed it a $#@!load (every time I came to a stop or even at idle).

    If it looks similar to the video I'd say you have valve stem leakage, if its very brief/ dosen't happen everyday its prob turbo seals. Mine smoke a tiny bit every now and then.

    What year car?
    I have been fully catless for 10k miles. If you dont mind, how much did it cost you to fix the valve stem seals?
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    You mentioned that once the car has come up to operating temp that the smoke does not appear. Could it not be condensation? Also when the smokes coming out it should leave some sort of residue on the exhaust tips. Dab your finger and check it out. Clear? Oily?
    Last edited by 123ersan; 09-30-2013 at 05:18 PM.
    Trebilabackend/JB4 - VVT stage 1 - CP-e downpipes - wagner evo2 FMIC - ER charge pipe - Forge diverter valves - BMS DCI - n55 mids - evolve race exhaust - KWv3 - Quaife diff - huge 8 pots Click here to enlarge

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    I have exactly the same, after cold start, some stop and start traffic and my gas car turns in a oil burning diesel engine, when continuing towards the highway the smoking stops. It's there but hard to replicate, but it's there let's say 3 out of 5 workdays.

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    I have an oil burning and whiteish/blueish smoking problem. It doesn't happen when I start the car but it smokes whenever there is a decelerative load on the engine, whether it be coasting or engine braking at low loads. Sometimes it's only mild to moderate smoke, sometimes it's severe billowing smoke. I've read that it can be due to the vacuum generated when decelerating which pulls the oil through the seals and then burns up. It also leaves a lot of black carbon residue all over the exhaust tips.

    I'm banking on it being the turbo seals which I can just replace with RBs in the future.
    Stuff

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    Click here to enlarge Originally Posted by MAC335 Click here to enlarge
    Maybe it only happens when cold because once it is warm the seals dont leak anymore? Coolant level has not gone down. Oil level says it is at max every time I check it. Click here to enlarge
    It doesn't happen when cold due to oil properties. When the oil is cold it's much thicker and therefore won't be as likely to seep through small leaks in the seals. Once it's warmed up it's much more fluid and will therefore leak.

    In regards to the oil level I can almost guarantee that you are leaking oil but it just won't show it yet, especially if you only recently started leaking or if you had a recent oil change. Mine is consuming oil at a rate of about 0.5-6L/1000km. There is a large leeway between the max oil level shown on the computer and the real max oil level, maybe almost 1L. I know this because I regularly have to top up my oil levels and when I dropped my oil for an oil change, at most only 5-5.5L of used oil came out and my computer dipstick was telling me I was at about the halfway mark. I assume the "low level" mark probably means that you have less than 5L. Computer dipstick max is around 5.5-6L. True max is around 6.5L.
    Stuff

  13. #13
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    Click here to enlarge Originally Posted by MAC335 Click here to enlarge
    Got just over 60k miles on the car. It is a 2007.




    Maybe it only happens when cold because once it is warm the seals dont leak anymore? Coolant level has not gone down. Oil level says it is at max every time I check it. Click here to enlarge




    I have been fully catless for 10k miles. If you dont mind, how much did it cost you to fix the valve stem seals?
    its a 4k repair at the dealer(Thank god for my 100k warranty!!) . I have a picture of the service sheet in this thread: http://www.bimmerboost.com/showthrea...Whiteish-smoke

    Keep an eye on your oil level, I was loosing a quart every 3 weeks 700-1k mile(s) range.
    Mines an 07 as well and I had 70k miles when I installed downpipes(no sec cats already) and I finally started notice smoke every time I decelerated or came to a stoplight. Friends did tell me my car would smoke a lil when driving behind me but I never noticed it until I went fully catless. Thought it was my turbos as well, turned it stock, dealer looked at everything and it was valve stems!!

    couple more question, do you have oil cooler? What are your oci's?

    My smoke was white unless under direct sunlight it had a small blueish hue but for the most part it looked white.
    08 328i, totaled by women driver
    07 335i, lots of mods.
    Now- 14 Focus ST
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    Click here to enlarge Originally Posted by ajm8127 Click here to enlarge
    This is a misconception. I depends on where the oil is burning. If it is burning in the cylinder, then yes, blueish smoke is common. But if unburnt oil gets into the exhaust, the smoke can be white.

    I told a garage full of techs that my car was smoking because if a bad turbo letting oil into the exhaust. On of the less illustrious of the group tried to tell me I was burning coolant not oil because the smoke was white. I wasn't going to argue about the finer points of engine diagnosis with a bunch of car techs I don't know so I just said, "Maybe". Once I pulled it apart it was apparent the tech was wrong. White smoke can be caused by oil.
    Makes perfect sense, thanks for clearing it up.

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