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Smoke on startup ?

 
Old 07-14-2014, 03:02 AM
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Elephant Chuck
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Default Smoke on startup ?

Who is getting significant startup smoke?

On the replacement engine, I get a visible belch on about 1/3rd of startups. The size of the belch varies, ranging from 'normal 911' to significant. It has to sit for 1/2 hour or more or there will be no smoke.

On the original engine, it was worse. More frequent and generally a larger belch.

Today I had a first time experience in that the smoke was more than a single puff on startup. It smoked heavily as I drove off, and continued for about 3 blocks. It was a lot of smoke.

This is now two engines, behaving similarly. I am plenty familiar with 911 engines giving a little puff on startup. This is way past normal for a new car.
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Old 07-14-2014, 03:51 AM
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JCBH
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Weird - my original engine seemed to consistently have a lot more smoke at startup. So far, I have not noticed any smoke since getting the new engine. Will keep an eye out for sure.
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Old 07-14-2014, 07:55 AM
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Elephant Chuck - what color is the smoke at start-up??. I have owned 2 other Porsches and they always had some blue smoke at start up. Not all the time but was obvious enough. I have learned that this is not a problem. Pretty common actually. The weird thing is my C2S Loaner never has any smoke at start up so I attributed that to the new 991 motor.

Now, if you are getting white smoke what temp is it outside and does it smell?. Some times when it is cooler out that is just a function of the heat hitting the cooler air and should have no odor.
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Old 07-14-2014, 08:28 AM
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Maverick787
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Should be fine as long as it's not black which would oil burning. Agree with the the temp change possible cause.
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Old 07-14-2014, 09:04 AM
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Thought Blue Smoke would imply Oil Smoke which would be natural from sitting on the bottom of flat engine?
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Old 07-14-2014, 09:47 AM
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Jimmy-D
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^ yes. My previous (2) Porsches always gave a puff of blue smoke at start up. I think black smoke is when oil is burning which is a different scenario - get out of car and run
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Old 07-14-2014, 10:17 AM
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Blue is oil, black is unburnt fuel (rich AFR), white is typically water. White can also be oil if turbocharged and the turbine-side oil seal in the turbo fails when hot, then subsequently sprays into the turbine housing and vaporises (rather than burning).

I tend to agree with Tacet but my MY99 Impreza STi, with its flat-4, doesn't blow any smoke at startup. Moisture on warm-up does pickup carbon in the exhaust though and deposit it on walls, garage doors, etc. but I very much doubt that this is what Chuck is seeing as, in my instance, it's only noticeable once deposited.

If it is blue smoke, perhaps the rings are still adjusting to the bores?

Edit:
The pistons are forged (source: wikipedia), so they are slightly undersized when cold because they expand more than cast pistons as they warm up. What this means is that the rings don't seal properly until they approach normal operating temperature and have expanded to the correct spec.

Scott.

Last edited by sk0t; 07-14-2014 at 10:39 AM.
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Old 07-14-2014, 10:57 AM
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I had it on my first engine, every 6 or 7 starts, especially if it sat a bit. With the new engine, it happened once. Blue smoke. Normal for GT3.
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Old 07-14-2014, 12:36 PM
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SanDiegoDavid
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I got my car back on Thursday. I have put almost 500 miles on over the weekend. I had one start up with smoke. There was enough smoke to concern others in the parking garage!
I had a kid in a Impreza WRX with straight pipes racing me in Rancho Santa Fe, he must have been in high school. I slowed down and let him pass, but he kept waving me up. Finally stopped and chatted a bit, he was going crazy over the car. I said I was breaking it in, so couldn't go too fast. The break in was a good excuse to talk him down from a friendly but stupid race!
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Old 07-14-2014, 01:01 PM
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Tacet-Conundrum
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Originally Posted by sk0t View Post
Blue is oil, black is unburnt fuel (rich AFR), white is typically water. White can also be oil if turbocharged and the turbine-side oil seal in the turbo fails when hot, then subsequently sprays into the turbine housing and vaporises (rather than burning).

I tend to agree with Tacet but my MY99 Impreza STi, with its flat-4, doesn't blow any smoke at startup. Moisture on warm-up does pickup carbon in the exhaust though and deposit it on walls, garage doors, etc. but I very much doubt that this is what Chuck is seeing as, in my instance, it's only noticeable once deposited.

If it is blue smoke, perhaps the rings are still adjusting to the bores?

Edit:
The pistons are forged (source: wikipedia), so they are slightly undersized when cold because they expand more than cast pistons as they warm up. What this means is that the rings don't seal properly until they approach normal operating temperature and have expanded to the correct spec.

Scott.
Funny, my old 2008 Impreza never blew blue smoke either. Having cylinders that lay flat on their sides affords he Boxster Style Engines a long life. Well at least with the Subaru's fours. The day I bought my Impreza they had an 1999 Impreza in for some work, that car had just a little over 500K miles on the Odometer.

Wasn't there a Porsche that was just about to hit 1 Million miles, believe it was a 356?

As for the Blue Smoke at startup there can be any number of reasons for this.
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Old 07-14-2014, 03:31 PM
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In this case it is definitely oil smoke. While it may look whitish to brown depending on the light, the smell is unmistakeable.

What I am seeing varies from start-to-start. Ranges from no smoke, to spraying-for-bugs.

When it's bad as SanDiegoDavid experienced, a bystander would definitely take note.

I haven't yet been around any other 991 GT3s for comparison. But I have a stable of 911s of various vintages, and what I am seeing could not dismissed as normal. If this is normal for a 991 GT3, then there is a design problem.

Last edited by Elephant Chuck; 07-14-2014 at 09:38 PM.
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Old 07-14-2014, 03:41 PM
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MaxLTV
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I have it about 1/3 of starts, same in old and new engines. I could not determine the pattern yet. 1000 miles on the new engine already.
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Old 07-14-2014, 04:30 PM
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Mike in CA
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I haven't noticed it yet on the new engine but I've only had the car back for a few days. It was an occasional occurrence with the old engine; nothing I'd consider abnormal for a boxer motor.
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Old 07-14-2014, 09:07 PM
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I am getting smoke too...
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Old 07-14-2014, 09:20 PM
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ONE episode thick blue smoke at start-up with new engine (indeed, seemed like it "belched" ... caught my attention) resolved within 10 seconds ... mileage on new engine (present 770mi - redelivered @ 273mi) = 497mi. Engine runs great. Attributed it to oil ... ?seating of rings during run-in period. Have now decided to run to 9000 rpm after putting 400+ miles on new engine.
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