Smoke during normal deceleration

Discussion in 'Mazdaspeed 3 Troubleshooting' started by tmillner, Sep 7, 2016.

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  1. tmillner

    tmillner Greenie Member

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    Hoping some one on here can help. I've done some research but would like opinions on my specific circumstances.

    Car has 78k on it, bnrs4 installed about 10k ago. Running an e30 mix, at 24 to 25psi and Stratified Tune. Recently installed a occ to help with blow by.

    Upon deceleration from high speeds, normal deceleration, once you stop you can see a puff of light blueish smoke fly past. Doesn't smoke at idle or during acceleration. Did a compression check all cylinders over 180 psi dry, and 185+ to 210 wet, not sure why the variance.

    My research has lead me to believe valve guides on the exhaust side. There is a layer of oil in the hot side IC piping, I haven't checked the rest yet or the turbo. I'm putting a new pcv valve in tomorrow anyway but wondering if anyone had any input before I go any further with a leak down etc.



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    tmillner, via a mobile device, Sep 7, 2016
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  2. tmillner

    tmillner Greenie Member

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    Bump

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    tmillner, via a mobile device, Sep 8, 2016
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  3. Raider

    Raider Administraider Administrator Platinum Member

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    I would do a leakdown test, as that could be it. Bad rings can give the blue smoke at decel.
     
  4. tmillner

    tmillner Greenie Member

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    With the leakdown if it's rings I'll read in it in the pan right? Strange this is it only does it occasionally

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    tmillner, via a mobile device, Sep 8, 2016
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  5. Slow6_pl

    Slow6_pl Greenie Member

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    Same thing happens to me occasionally, in for possible causes.
     
  6. tmillner

    tmillner Greenie Member

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    How much oil are you going through? Looks like im using about a qt every 250 350 miles. Will be doing a leakdown next week.

    Looking at new pistons and rods now

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    tmillner, via a mobile device, Sep 17, 2016
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  7. Slow6_pl

    Slow6_pl Greenie Member

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    Similar to your consumption, however it has reduced since I reworked my K04. I'm about to go with a different turbo, because the K04 was the first diagnosis for mass loss of oil. I need to look at rebuilding, but a college kid only has so much money. I'll have my guys do a leakdown, that sounds like the right thing to do.
     
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  8. tmillner

    tmillner Greenie Member

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    If you don't mind post results and findings

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    tmillner, via a mobile device, Sep 17, 2016
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  9. tmillner

    tmillner Greenie Member

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    Ok leak down test complete. Here are results

    Screenshot_20161016-114409.jpg
    Screenshot_20161016-114455.jpg
    Screenshot_20161016-115833.jpg
    Screenshot_20161016-114426.jpg

    Cylinder #4 had the most leakage. Had the dip stick pulled out and didn't hear any air leaking to the pan. Sounded like all the leakage was going to the exhaust.

    Here is a compression test from a few weeks ago

    20160925_124458.jpg
    20160925_123253.jpg
    20160925_123410.jpg
    20160925_123538.jpg

    All were 180 and above, I think there was oil in one cylinder causing it to be higher.
    So right now I'm leaning more to exhaust valve seals.

    Wanted to post results to see what others thought.

    @Raider thoughts?


    Ps if the pics don't show up I'm terrible with this app

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    tmillner, via a mobile device, Oct 16, 2016
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  10. tmillner

    tmillner Greenie Member

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    Guess i didnt do the twitter name thing for raider right.

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    tmillner, via a mobile device, Oct 16, 2016
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  11. VTMongoose

    VTMongoose John/MD1032 Platinum Member

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    Valve seals don't affect engine compression.

    I find it hard to believe that you could have 25% leakdown on all cylinders and still produce 180 psi during a compression test. Are you sure you did the leakdown test correctly?
     
  12. tmillner

    tmillner Greenie Member

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    Yeah, 0 out gauge, set cylinder to tdc connect. Car still runs strong.

    Compression test was to show for rings not for valve seals

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    tmillner, via a mobile device, Oct 16, 2016
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  13. tmillner

    tmillner Greenie Member

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    Bump bump for any additional advice

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    tmillner, via a mobile device, Oct 19, 2016
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  14. Slow6_pl

    Slow6_pl Greenie Member

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    So we've eliminated turbo seals, rings, and compression looks good.. and you're still thinking exhaust valves sears, correct? Just trying to summarize and brainstorm. You stated there was oil in your hot side piping, do you have any catch can set up? The oil would have to get into the intake or piping somehow, if that's the oil that's burning upon deceleration.
     
    Slow6_pl, via a Samsung mobile device, Oct 20, 2016
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  15. tmillner

    tmillner Greenie Member

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    I just replaced pcv valve and put a catch can on. Only a little residue on hot side. Don't think it's turbo seals.


    I do still think exhaust seals

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    tmillner, via a mobile device, Oct 20, 2016
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  16. mangosmoothie

    mangosmoothie Platinum Member

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    get a borescope. See if you can peek at an exhaust valve while it's open in the combustion chamber. Might be hard to see but look for oil on top of the valve. If you can't see, pull the exhaust mani and look at the exhaust valves through there. If there's oil on top of them, you know it's valve guides and or stem seals.

    Bad valve guides won't really show up on compression or leak down tests.
     
    Last edited: Oct 20, 2016
  17. Slow6_pl

    Slow6_pl Greenie Member

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    Because I'm a little mechanically stupid, how would the guides or seals cause oil burning?
     
    Slow6_pl, via a Samsung mobile device, Oct 20, 2016
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  18. tmillner

    tmillner Greenie Member

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    Letting oil pass by into the combustion chamber during high vacuum.

    I will say that there is oil on top of the pistons


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    tmillner, via a mobile device, Oct 20, 2016
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  19. mangosmoothie

    mangosmoothie Platinum Member

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    the point of valve stem seals is to prevent oil in the top end from running down the valve guides. If the seals are leaking, oil will travel down the valve guide. then it sits on top of the valve. Every time the valve opens/there is high vacuum, it can get into the combustion chamber and be burned or blown out the exhaust mani. Worn guides mean a bigger gap so it's easier for oil to get down the guide. It's pretty much impossible to measure valve guide clearance with the valves still in the head. So the tell tale sign is oil pooled on top of the valves. If the seals were not leaking, oil would not be able to pool on top of the valves. It is possible to replace valve stem seals with the head on the block. Valve stem seals aren't expensive, it's just a lot of labor. So if you diy and have time, might be worth a shot. If not, either live with oil burning or have the head pulled and new guides pressed in, get a new head. And if the head is off.......... might as well refresh the whole thing.

    here is the top of the valve. If you took off your valve cover and removed the cams, buckets, valve springs, this is what you would see. The seal is the part with a coiled spring. When the engine is together and running, oil is being thrown all around in there.

    [​IMG]

    so if that seal isn't working, oil travels down the guide and pools on top of the valve. So it can get burned/blown out the exhaust port

    [​IMG]

    this isn't entirely true all the time, but if you see oil on top of the piston, is it on the edge or in the center? Edges make me think issue with rings, center makes me think dripping down from valves.

    Bad oil control rings won't really show up on compression tests either, so it could be that too. Or rings and valves at the same time
     
    Last edited: Oct 20, 2016
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  20. tmillner

    tmillner Greenie Member

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    This is why i come here. All stuff i know but still good info and explication

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    tmillner, via a mobile device, Oct 20, 2016
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