JB Posted 25September, 2016 Report Share Posted 25September, 2016 Hi guys, a bit worried. When I have started the car cold in twice in the past two days I am getting a big waft of black smoke from the exhausts upon start up then it immediately clears.normal? Is it because it's being started and moved and not driven? Haven't noticed it before. It's in at porsche tomorrow so I was hoping I can have some understanding before raising it.thanks Link to comment Share on other sites More sharing options...
StevepGT3 Posted 25September, 2016 Report Share Posted 25September, 2016 Normal Link to comment Share on other sites More sharing options...
JB Posted 25September, 2016 Author Report Share Posted 25September, 2016 Hi Steve, it's a lot! And I'm old school so smoke means issue. Is it oil sitting after build up? Thanks Link to comment Share on other sites More sharing options...
GUT Posted 25September, 2016 Report Share Posted 25September, 2016 Yup normal.Do yourself a favour and refrain from googling it. You'll be up till 4am reading countless threads and theories.My Carrera did it a bit, then it didn't, but sometimes does. Not much though.The 930 didn't, then did a bit, then didn't. Now sometimes after an extended break. If I park it on the wrong angle and oil doesn't drain out of the turbo fully, there's a smoke screen - only happened a couple of times - scared the sh!t out of me.My other one with the 964 turbo engine doesn't at all. So far.Normal.EDITAnd I just realised this was in the watercooled section. So there ya go. Link to comment Share on other sites More sharing options...
StevepGT3 Posted 25September, 2016 Report Share Posted 25September, 2016 Mine won't do it for ages, and then Wooshka garage is full of smoke, the 993 did it too.It's just one of those things that boxer engines do occasionally to cause sleepless nights. Link to comment Share on other sites More sharing options...
firstone Posted 25September, 2016 Report Share Posted 25September, 2016 My Boxster did it and it was the AOS needed replacement. It has done it again since a couple of times, scared the sh1t out of me.I had started it, let it go through the choke to idle and moved it, then switched it off. The next start up was smoky.Rare in my case. Link to comment Share on other sites More sharing options...
MFX Posted 25September, 2016 Report Share Posted 25September, 2016 Black smoke is generally not an issue (running rich). White/bluish smoke is oil, which can be more of a concern. Then it can be AOS (easy fix) or something more sinister, but that sounds fine. Link to comment Share on other sites More sharing options...
Fraz Posted 25September, 2016 Report Share Posted 25September, 2016 They hate a cold start then turn off before getting fully warmed up. I always at least take the 64 for a drive around the block, if I just move it around the garage she will blow smoke on the next start. Link to comment Share on other sites More sharing options...
Mike737 Posted 25September, 2016 Report Share Posted 25September, 2016 Same here. They really hate not being driven, so if you're moving cars around, run it for a couple of minutes instead of a quick startup and shutdown - which can cause other false scares Link to comment Share on other sites More sharing options...
JB Posted 25September, 2016 Author Report Share Posted 25September, 2016 Thanks guys, makes me feel much better. Past two days we have been working around the house with a skip so have moved her out of the garage into the road and back in twice, both occasions black smoke even though I have started and let it run for a minute or two before moving.will mention aop to Porsche tomorrow however have only had this come up in the past two days with not being driven so theory makes sense. Knowing their finely tuned makes sense.thanks again can sleep tonight.....? Link to comment Share on other sites More sharing options...
Peter M Posted 25September, 2016 Report Share Posted 25September, 2016 Hi Steve, it's a lot! And I'm old school so smoke means issue. Is it oil sitting after build up? Thanks JBTo give you a more complete answer the black smoke on start up when very cold is from the richer than normal mixture needed to aid starting. Since the catalytic converters aren't up to temperature they allow the sooty hydrocarbon rich exhaust to be seen at the tailpipe.The other blue smoke that the others have hinted at above comes from engine oil finding its way into the combustion chambers after sitting a while. Since the cylinders are horizontal and in the Mezger engines the oil tank is higher than the sump, it's pretty much inevitable and part of the charm. You won't notice it often, usually only occurs when your non enthusiast wife, family or friends are watching! Link to comment Share on other sites More sharing options...
Mike737 Posted 26September, 2016 Report Share Posted 26September, 2016 The other blue smoke that the others have hinted at above comes from engine oil finding its way into the combustion chambers after sitting a while. Since the cylinders are horizontal and lower than the oil tank it's pretty much inevitable and part of the charm. You won't notice it often, usually only occurs when your non enthusiast wife, family or friends are watching!Not sure this is so true with watercooled as it's a wet sump these days, but the possibility is still there since it pumps oil to the top of the engine on startup. So a quick startup and shutdown could cause what you are talking about on the m96 engine onwards since the oil pumps moves a significant amount of oil back up to the top of the engine during startup. GT series engines from my understanding are still all dry sump. Link to comment Share on other sites More sharing options...
JB Posted 26September, 2016 Author Report Share Posted 26September, 2016 usually only occurs when your non enthusiast wife, family or friends are watching!Uncanny..? Link to comment Share on other sites More sharing options...
Shady Speedway Posted 26September, 2016 Report Share Posted 26September, 2016 I understood the rings can align at times. If they are all at '6 o clock' after shut down. Oil can make it's way along to the combustion chamber. Random. Link to comment Share on other sites More sharing options...
Peter M Posted 26September, 2016 Report Share Posted 26September, 2016 Thanks Mike for that correction. You are right about the different engine type and I regret I didn't give a clearer answer at all in the end! EDIT: Clarified my original post to reference Mezger engines especially Link to comment Share on other sites More sharing options...
DJM Posted 26September, 2016 Report Share Posted 26September, 2016 Mine won't do it for ages, and then Wooshka garage is full of smoke, the 993 did it too.It's just one of those things that boxer engines do occasionally to cause sleepless nights. ditto with my GT2. Link to comment Share on other sites More sharing options...
Mike737 Posted 26September, 2016 Report Share Posted 26September, 2016 Thanks Mike for that correction. You are right about the different engine type and I regret I didn't give a clearer answer at all in the end!No worries Peter. Definitely filled in some knowledge for me on the aircooled blowing smoke Link to comment Share on other sites More sharing options...
JB Posted 29September, 2016 Author Report Share Posted 29September, 2016 Hi guys, thanks again for the help and advice.got the car back today from PCB and along with some other minor warranty things they fixed, they replaced the AOS. Apparently there was something wrong with it, was blocked and taking in too much air....All good now, driving like a dream.cheers Link to comment Share on other sites More sharing options...
Mike737 Posted 30September, 2016 Report Share Posted 30September, 2016 Glad to hear it's sorted. The AOS is a bit of a pain on the watercooled series. Was it an engine out job on a 4S since it has a different engine? Link to comment Share on other sites More sharing options...
JB Posted 30September, 2016 Author Report Share Posted 30September, 2016 Hi mike, dont believe so, had the car for a day and a bit, replacing bushes, door lock and battery cables, so I would say no?they didn't seem too phased about it.. Link to comment Share on other sites More sharing options...
Tommytt Posted 16November, 2016 Report Share Posted 16November, 2016 I had/ have the same. Normal and sporadic.The last time I pulled the car out the garage to clean it - no smoke. The started it to put back in the garage and ----- puff (always impresses the wife )if it's ongoing it could be the oil separator needing repayment. as @shadyspeedway says, it's just oil making it was at irregular intervals. Link to comment Share on other sites More sharing options...
Mike D'Silva Posted 17November, 2016 Report Share Posted 17November, 2016 I understood the rings can align at times. If they are all at '6 o clock' after shut down. Oil can make it's way along to the combustion chamber. Random.Interesting... when re-assembling a new motor, we all go to great pains to align the rings and 9, 12 and 3.. so that there is no chance for them to align or so that oil doesnt seep through if the ring gap is at 6pm position.. but if the rings all move around anyway, then why bother with alignment during assembly? Link to comment Share on other sites More sharing options...
Tommytt Posted 17November, 2016 Report Share Posted 17November, 2016 there is no chance for them to align or so that oil doesnt seep throughHi Mike, I am far from qualified. any explaination here as to why this might be happening? Link to comment Share on other sites More sharing options...
Peter M Posted 17November, 2016 Report Share Posted 17November, 2016 Rings slowly rotate around the piston. This is the reason that they are pinned on two stoke engines to prevent them rotating so that a ring end can't spring out the exhaust port and get jagged.As for aligning the ends of the ring ends so they don't coincide when rebuilding I don't know. OCD I guess. Link to comment Share on other sites More sharing options...
Shady Speedway Posted 17November, 2016 Report Share Posted 17November, 2016 Interesting... when re-assembling a new motor, we all go to great pains to align the rings and 9, 12 and 3.. so that there is no chance for them to align or so that oil doesnt seep through if the ring gap is at 6pm position.. but if the rings all move around anyway, then why bother with alignment during assembly?Yeah. This is what I was told at trade school. evidently once the bores are glazed and the tension of the new ring has been lost through wear things can move apparently? An old P car guy explained to me. Link to comment Share on other sites More sharing options...
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