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I have a 96 Legacy Outback with a 2.2 from a 94, heads from a 97, and a intake from a 96. I rebuilt the engine a few months ago due to massive oil consumption caused by bad rings. The engine never smoked at all. The rebuild went great and it runs smooth but once in a while I would have a big puff of white smoke on startup after it sat all night of for at least a couple hours. Pure white smoke, no sweet smell at all, definitely not condensation and it would last about 3 to 5 seconds and the cloud would linger for a while. It didn't use a single drop of oil or coolant from what I could tell. After 7k I decided to tear it apart again and do what I should have done in the first place which was 1 use oem head gaskets and not Topline gaskets that came with my rebuild kit and 2 replace the valve stem seals.  I had the heads checked and they were still flat. Got everything back together and after maybe the 10th time starting it I got the white cloud again. I'm at a loss. Could it be that I have a injector sticking open and that extra fuel gets burned off? . Been working on cars for most of my life and never had this problem before. I'll try to take a video when I get a chance.

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Just had another thought. If it was coolant it would probably only be a few drops that would cause it to smoke like that and I might not notice a fluid level change. I just noticed that the IAC valve has a coolant line running thru it for whatever reason. Any chance it could be seaping into the intake thru that?

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gravitate,

 

Had the exact same issue on a Toyota Cressida (1982?) years ago, and it turned out to be bad valve stem seals. They were allowing oil into the cylinders overnight, and it burned off immediately after startup for 10 seconds or so. That was a straight 6 back them.

 

Not certain if a boxer would do the same?

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... once in a while I would have a big puff of white smoke on startup after it sat all night of for at least a couple hours. Pure white smoke, no sweet smell at all, definitely not condensation and it would last about 3 to 5 seconds and the cloud would linger for a while. ...  I'm at a loss. Could it be that I have a injector sticking open and that extra fuel gets burned off? ...

 

No, because Extra Fuel, burns out in a Black Smoke, not "pure White" smoke.

 

 

... If it was coolant it would probably only be a few drops that would cause it to smoke like that and I might not notice a fluid level change ...

 

No, because Coolant doesn't make White Smoke, it makes Blueish Smoke, usually.

 

 

I agree with this:

 

... Did you replace the PCV valve? Hoses going to the valve are clear or carbon/sludgey buildup?

 

So, I kindly suggest you to check the routing of the PCV system, and check the state of the PCV Valve.

 

Let us know the results. Kind Regards.

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Coolant is white smoke, but Subaru head gaskets don't fail that way anyway they have already replaced them with OEM gaskets so its not head gaskets.

 

Oil is usually blue smoke, but small amounts of oil will cause a light gray smoke that can look white.

 

I agree the PVC is a good place to start though.

Edited by mikaleda
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So I checked the PCV and it looked clean and moved freely. I had cleaned it when I did the rebuild so I figured it was good but I decided to replace it with a OEM one because $10 aint bad. So far it hasn't smoked once and that was over 1200 miles ago. So I'm keeping my fingers crossed. I hear everyone always say to check you pcv valve on a variety of problems but until now I never realized how important it was. Thanks for your help guys. I'll let you now if it smokes again

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  • 2 weeks later...

There's a funny o-ring that goes in the back corner of the oil pan on the tube that runs up to the bottom of the oil separator. Did you replace that o-ring?

Normally it causes high oil consumption, so I'm no sure that would be your problem, but I ask just to try to rule it out.

 

Were the valve covers hot tanked? If the baffle inside one is clogged you can get oil sucked into the breather tube.

Breather tubes are clean and clear?

 

Separator plate was replaced?

Is the tube going into the separator clean?

PCV hose and the Y are clean?

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I most definitely replaced that oil ring. The whole engine was spotless when I put it back together and I cleaned the valve covers both times I had them off.  The breather tubes are clean. The pcv hose and Y are clean. I replaced the Oil Separator with a aluminum one. It's only happened once  that I've noticed sense I did the head gaskets and valve seals, where it i was doing it at least once a day when I decided to redo the heads. Weird

Edited by gravitate
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Its sucking oil in from somewhere.

PCV is usually the most likely in my experience with Toyota and nissans doing similar to this, but I haven't had a Subaru do it.

 

Is there any pattern to when it happens? Cold start? Warm start? Drive for 10 minutes, stop then start an hour later?

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Morning starts or after sitting a hour or so. What's weird is how it's only happened once in the last couple or so thousand miles. And when it was doing it more frequently before it could go a week without doing it then everyday for a while. That's why I thought maybe a fuel injector not shutting off all the way at times EDIT it happened again today, a smaller poof of smoke but still enough to notice

Edited by gravitate
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  • 4 weeks later...

So it's happening more frequently now.

I took the plugs out and stuck a cotton rope in the hole and found a small amount of oil  on the end in the 3 and 4 cylinders. Although it didn't smoke after starting it this time.

I opened the throttle body butterfly and looked in and it looks pretty clean so I doubt any oil is getting sucked thru the pcv.

Whats weird is that it slowly got worse after the rebuild and then the same after the head gasket replacement and valve stem seals. I'm thinking the oil is breaking down and getting thinner so it's seeping by something. Whats your thoughts. Could the rings not have set properly and sometimes it gets by them ?I highly doubt it but I also doubt the valve seals are leaking again or even leaked in the first place considering that they hardly ever have issues on these motors.

No coolant loss and no oil loss that I can tell but it wouldn't take much

I'm gonna add a bottle of Lucas to see if it thickens the oil up and stops it.

Ugh its pretty frustrating considering I have a Mobile Mechanic sign on my back window and I have a huge puff of white smoke when I start this thing up.

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When was the last time you changed the oil? What weight are you running? Synthetic or conventional?

 

I'd drain the oil, and run a quality 10w 30 synthetic along with a new oil filter, and see if it continues or not. If you still have the same oil in it that was used during the break in, it definitely needs replaced ASAP. Wouldn't mess with Lucas or any other oil additives. If you change the oil routinely and use correct weights for the application, you shouldn't need to touch the oil cap and only the dip stick needs a periodic inspection.

 

Many car companies are switching to extremely thin 0 and even 5w which can be too thin on engines not recommended for it or with looser tolerances, extremely HOT conditions, etc. Since you have a hodge podge of different year engines and live in AZ, I'd run fresh 10w 30 and see how it runs and see if it stops. IF you are in a very hot region of AZ, consider a 10w 40 instead as the extra desert heat in the summers will be harder on the thinner oils. 

 

You also might want to try and snag an oil catch can for the PCV line that many run on turbo'd engines. The oil will instead accumulate in the catch can vs. reaching the PCV valve (if it's even reaching that). I think there's a higher chance of oil getting into the line under high vacuum when engine is cold, but not positive.

 

 

Also, as others have pointed out, white smoke that lingers is usually coolant. When turbos completely fail, they'll leave huge plumes of it. Oil smells differently when burning (completely noxious when a diesel engines burns it) and is typically darker with a bluish tint, and smoke amount is determined by how much is getting burnt.

Edited by Bushwick
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