Smoke on startup ?
07-14-2014, 03:02 AM
#1
Former Vendor
Thread Starter
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.
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.
07-14-2014, 03:51 AM
#2
Rennlist Member
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.
Jeff
Jeff
07-14-2014, 07:55 AM
#3
Race Director
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.
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.
07-14-2014, 08:28 AM
#4
Should be fine as long as it's not black which would oil burning. Agree with the the temp change possible cause.
07-14-2014, 09:47 AM
#6
Race Director
^ 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
07-14-2014, 10:17 AM
#7
Instructor
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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.
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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07-14-2014, 12:36 PM
#9
Rennlist Member
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!
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!
07-14-2014, 01:01 PM
#10
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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.
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.
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.
07-14-2014, 03:31 PM
#11
Former Vendor
Thread Starter
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.
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.
07-14-2014, 04:30 PM
#13
Race Director
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.
07-14-2014, 09:20 PM
#15
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.