Smoking and Oil Loss (Troubleshooting Nightmare)

Discussion in 'Mazdaspeed 3/6 Engine' started by VashEXE, Jan 29, 2017.

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  1. VashEXE

    VashEXE Silver Member

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    Alright guys, I've beat my head against the wall for a while now and I've decided to see if any of you guys have any other input on my smoking nightmare that's been going on for a while now. I'll start with the details and what I've done so far.

    My car started smoking during deceleration when I was downshifting. Most of the time when I roll up to a stop light I'll have a cloud of smoke that was trailing me whoosh up in front of my car. I can see puffs of smoke sometimes when shifting as well, so I assume that it's doing it most of the time when I shift. The car does not smoke at all during idle, even when revving it pretty hard.

    I have done a compression and leakdown test on the car. Compression looks good at 175-180psi on each cylinder. Pretty good for almost 130k miles. The leakdown was done dry and all cylinders were sitting at around 25% leak. I haven't done a wet test to verify if the leak decreases or not, but that's for another time.

    I have verified that my Perm plate and vented catch can were breathing properly and there weren't any obstructions in the line or anything. The can never really has much in it, but it does have a small amount of gunk in it during each oil change.

    I've inspected the turbo on both compressor and exhaust sides for possible oil seal issues (not likely because EFR), and both sides were dry.

    The car runs pretty good and I don't really have any other complains besides how much oil it's burning. All of my logs look good and don't show any strange knock or anything.

    I have to put about half a quart in every couple hundred miles due to how much oil it's burning, which means I have to top it off at least once a week unfortunately...

    My current thought is possibly something valve related (seals, guides, etc.), but generally with something valve related you'd see smoke during cold starts, which I don't.

    If you guys have any other ideas on what this might be, I'm all ears. I'd really like to get this figured out.

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  2. VashEXE

    VashEXE Silver Member

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    A little update on this;

    I've changed my driving habits a bit and no longer revmatch downshift when coming to a stop. I no longer see smoke when rolling up to a light and I don't see oil loss like I did before. I still do smell a little bit of stank, but I do have a vented catch can, so it's probably just that.

    I'm going to take a look under the intake manifold later this week and examine the injector seals for shits and giggles. I'll also be looking at the perm plate and verifying there's nothing weird going on with it that I couldn't see from under the car.

    Any other bright ideas are welcome.
     
  3. HawkeyeGeoff

    HawkeyeGeoff MSO Chicks Greenie Member

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    @VashEXE if you suspect something valve seal related, remove the intake manifold and inspect for oil in it. If it's doing it bad enough there will be pools.

    How much oil are we talking here? And 25% really isn't great for leakdown, fyi. That's getting to the point that you will blow by a bit regardless.
     
  4. mangosmoothie

    mangosmoothie Platinum Member

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    I suppose guides ocould be worn enough or seals could be leaking just so oil is sucked down under heavy vacuum, but not otherwise. Guides generally don't show up on compression. When you do a leakdown, is air going to the bottom end, or through the top? If you're lazy and don't wan to pull the IM, you might be able to stuff a borescope in the spark plug hole, rotate the engine by hand, and watch the valves when they open for oil residue.
     
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  5. HawkeyeGeoff

    HawkeyeGeoff MSO Chicks Greenie Member

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    I dig the lazy efforts. +1
     
  6. VashEXE

    VashEXE Silver Member

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    The only thing that makes me think it ISN'T valve related is the fact that I see no smoke during cold starts. If it were pooling up on top of the valve you'd usually see smoke on a cold start, which I don't. I am pulling the intake mani out in the next few days as well, so I'll inspect that when I pull it off.

    The amount of oil I lose is directly related to how much I revmatch downshift while driving. When I am downshifting a lot (lots of stop and go traffic and stop lights) I will get clouds of smoke out the back of my exhaust. Recently without downshifting I get no smoke and no noticeable oil loss.

    I've read some different opinions on leakdown tests saying that the motor being warm/cold can effect results, but I'm not really sure what is correct. Compression is good, but the leakdown is definitely a bit higher than I'd like it to be. I was thinking about redoing the leakdown with the motor warm or with some oil in the cylinders to see if it effects the results at all.
     
  7. mangosmoothie

    mangosmoothie Platinum Member

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    All I'm saying is the guides/seals could only be leaking under vacuum. That could explain why you don't see it on a cold start.

    Just spit ballin
     
  8. HawkeyeGeoff

    HawkeyeGeoff MSO Chicks Greenie Member

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    Cold start = one big vacuum event and as it pulls the engine rpm's down. Yeah?
     
  9. VashEXE

    VashEXE Silver Member

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    That's what I'm unsure of. It's definitely under vacuum on a cold start, but I'm not sure if the vacuum on the cylinder is as high during a cold start as when you're engine braking down from higher RPMs. I'm assuming since the RPMs would be higher than a cold start while engine braking the cylinder vacuum would be higher, but I don't know for sure.
     
  10. mangosmoothie

    mangosmoothie Platinum Member

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    I was thinking engine not running=no vacuum therefore no oil pooling on valves, and no smokey start. I didn't think about it that way. However, I don't think that is as extreme as higher rpm engine braking vacuum.

    I guess high vacuum could also pull oil up from the bottom end. You can have good compression/compression rings with oil control rings that aren't working so well.

    Sounds the issue is only under vacuum

    Still spit ballin.
     
  11. HawkeyeGeoff

    HawkeyeGeoff MSO Chicks Greenie Member

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    Vacuum pulls oil down. Hence when you do break in procedure you want to pull oil down the walls to rid it of any metal particles.
     
  12. mangosmoothie

    mangosmoothie Platinum Member

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    I was thinking more oil could be making it past the rings. The oil control rings aren't scraping walls on the way down, and that vacuum is pulling the little bit of oil on the walls up past the rings. Then the rings will push that oil into the combustion chamber on the upstroke. But even then, bad oil control rings wouldn't be specific to engine braking.

    Sounds like valves, catch can, or turbo seals. I still think a bore scope into the combustion chamber would give some answers, especially if it's exhaust side valves/seals leaking. Obviously pulling the intake mani won't show that. It's also possible he can see oil in the combustion chamber. If it's on the outside of the piston, probably rings.
     
    Last edited: Feb 9, 2017
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