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Smokey When Starting


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Hi Folks,

 

1st Post!

 

Just had my OIL LEAK FREE 2001 Boxster S Tiptronic gearbox serviced &engine oil got changed at the same time.

 

Question; I now appear to have blue smoke upon first starting the car from cold. Any ideas?

 

I thought either a blocked breather or not so good, valve stem seals?

 

CheersFrom Scotland

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Hi Folks,

 

1st Post!

 

Just had my OIL LEAK FREE 2001 Boxster S Tiptronic gearbox serviced &engine oil got changed at the same time.

 

Question; I now appear to have blue smoke upon first starting the car from cold. Any ideas?

 

I thought either a blocked breather or not so good, valve stem seals?

 

CheersFrom Scotland

 

 

Check the car's AOS system.  Easiest way is to try to remove the oil fill cap in the rear boot while the engine idles; if it comes off reasonably easy, you are fine.  But if it is a bear to get off, the AOS needs to be replaced.

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Got it. Cheers.

Air & Oil Separator.

 

I used to be a mechanic a long time ago . How fiddily is it & is there more checks to do before I order one , other than removing the Oil Filler Cap?

 

Not really, if the oil cap is difficult to get off, the vacuum level is too high because the AOS has failed.

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Got it!

 

Bang On, AOS giving me lots of back pressure through to the Oil Filler Cap. Thanks, I think? :thankyou:

 

Question; Is it still okay to drive or should I put if off the road until I replace the AOS? :wrench:

 

Cheers

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Got it!

 

Bang On, AOS giving me lots of back pressure through to the Oil Filler Cap. Thanks, I think? :thankyou:

 

Question; Is it still okay to drive or should I put if off the road until I replace the AOS? :wrench:

 

Cheers

 

I would keep it off the road until it is fixed.  When the AOS fails catastrophically , they can suck in enough oil to hydro lock the engine and destroy it.  Not worth the risk.............

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When mine went I disconnected the tube from the manifold and plugged the manifold end, that way it cant generate vacuum, wasn't great but it ran well enough to get me about before I got it fixed.

 

Not necessarily a great idea; these are low tension piston ring engines, and killing all the vacuum to the crankcase can lead to other issues, such as burning oil and blowing out oil seals and gaskets.

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Dont follow that idea, mine did neither. i see there is another topic on here where the same was done, provided it can breathe I dont think there is a problem. The AOS is more an emissions device. But hey, go with what you feel is right.

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Dont follow that idea, mine did neither. i see there is another topic on here where the same was done, provided it can breathe I dont think there is a problem. The AOS is more an emissions device. But hey, go with what you feel is right.

  The AOS is more than just an "emissions device", it provides a consistent low vacuum level (around 5 inches of water) inside the crankcase that serves multiple functions.  First, and perhaps most importantly, it relieves any blow-by pressure build up which can keep low tension piston rings from sealing properly, which will cause loss of power and oil consumption.  In addition, the vacuum in the sump lowers the boiling point for any water or fuel accumulated there, allowing it to be converted to vapor and pulled into the intake system to be burned off before it can build up to levels that cause problems.  These engines also use silicone type sealants on flat machined surfaces on the sump cover and cam covers, as well as very low tension rear main seals, particularly the newer style PTFE seal, which can start leaking if there is any pressure build up over time.  You can also blow out the cam plugs on the cam covers as well (they are just a friction fit plug).

 

How quickly and to what level these problems will happen is dependent upon the miles on the engine, ambient weather conditions, and how the car is being used.  Just leaving the vacuum source line disconnected can help relieve some of the pressure build up, but not in all cases, plus it does nothing to address the ring seal problem and is particularly bad when it comes to build up of water and fuel in the oils.

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I understand the reasons for the vacuum and the low tension rings, the question is how much if any damage would occur with a small amount of usage while vacuum disconnected, I'm not talking long term use. While it is obviously better to avoid driving if you can it is certainly worse driving with it connected. So neither probably advisable, but disconnected better of the two if you have to drive. Anyway my 2000 80k Boxster suffered no permanent damage, drove it for about a week, drove the 30 miles to the opc to have the aos replaced, no issues since.

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  • 2 months later...

I am a newbie to the Porsche world,  entering when I bought my wife a 2001 Boxster S as a summer car.   90k miles.     We periodically were having the massive white smoke clouds this Spring.   In pouring through various forums,  it all pointed to the AOS.  And so, I went that route.    12 hrs later after practicing being a contortionist  (for a job that really is conceptually very simple, and only involves 3 hoses and a few mounting bolts!), the new AOS was installed.

 

But . . . periodically, the huge, impressive (to me, not so much to the poor folk behind the car) white smoke cloud still happens.   I'm wondering if I could have screwed up the AOS installation?  But go back and look at it, all looks good, it's solid in the attachments, and hose connections.

 

As my wife continues to drive it,  we burn through a little oil, and my son periodically checks it and tops it off . . . . and this problem gets a little worse.

 

Finally, out of frustration, I contact a private Porsche mechanic in Lexintgton, MA who is very well recommended, but who we have not seen yet.  Nonetheless, in listening to the problem,  he makes two simple suggestions.

 

1.  How high is your oil level?  Boxster is very sensitive to both high and low oil levels he says.  Keep it at 7/8 he says, and above 1/2, at all times.  (A little vague as to whether that's by the electronic gauge or dipstick)

 

2.  Do you KNOW what viscosity/weight oil you are using?  The Boxster is also hypersensitive to using the right oil weights.

 

So, after this call, I go out and check the oil, and my well-meaning son has the oil level topped off to at-full, or slightly over-full on both oil level readings.  And, since this was a new (to us) car, bought from a dealer, I cannot be 100% certain what weight/viscosity the oil level is.

 

So, I decide to simply go to the basics here,   Changed the oil myself,  using an oil as-recommended by the the Owner's manual, but I pick the heaviest weight oil of the range of oil recommendations made in the manual (since the car is only used for warm weather summer driving).  And,  I make sure that I very carefully do NOT fill to past 7/8th on either the dipstick or the electronic gauge after running the engine and filling the new filter.

 

OK,  let's see what happens.

 

What happened was . ..  problem solved.   A simple management of engine oil (type and level)  accomplished a complete end to the huge white smoke problem.  We get less smoking (almost nil)  while idling in the garage, and not a single huge-puff incident since.  

 

To be data based about it, in the 4 month period March thru June, we were experiencing about 2 huge white puffs per month.  In July and August, post oil change, and with ultra careful oil level management,  we are getting zero incidents of huge white smoke puff per month.

 

 

I sense I probably did not need to have replaced that AOS.  

 

D

Edited by dastrauckas
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