TT Smoke on Startup - Getting to the bottom of it

[InsBro]

Okay - I know it was posted a while ago but here are my findings - my car has done it 4 times now

Firstly oil level makes no difference - I assumed when full (1 bar from the top) it was more likley to do it

I always let the turbo's cool down after a spirited run for quite a distance (plus it keeps the locals happy be driving steadily through the village) - So hot shut down is not a cause

2 of the 4 times are when its only been parked for 30 mins or so rather than let cool down 100% for 3-4 hours so thats out of the equasion as Ive been in and out of the office alot recently and it hasnt done it since.

The other 2 times are both first thing in the morning one was today (ambient air temp 8 degrees car temp from garage 10 degrees) The other was when we had the major frost 4-5 weeks ago (garage temp 1.5 degrees air temp -4 degrees)

Thats it I cant see any pattern at all in why it does it.

Anyone else any idea?

Jez

[Glenn Mc]

Glad this isn't just mifffing me :(

I have tried to work out a pattern, but failed too.


Could be anyting to do with cornering or accellaration forces, just before it is switched off ?


G.

[InsBro]

Could be anyting to do with cornering or accellaration forces, just before it is switched off ?
G.

Or Lack of? As my drive home last night was the least spirited for weeks due to oncoming traffic and the fact I can get the PSM light to flash away in 3rd with the current state of my rear tyres :D

Jez

[Gastro]

Mmm - its confusing isn't it.
The older air cooled's were a little more predictable since a lot was to do with oil passing between the pistons in engines that had relatively slack tolerances.

With the more modern 911/boxster's I'm not entirely sure its oil that causes the 'smoke' - more a rich mixture with a bit of oil (does that make sense ?).

My boxster would do it - but predominantly (not exclusivley) if I did a short journey and then let the car stand overnight to be restarted the following morning........

Does this shed any light on the matter ? Perhaps not :o

[InsBro]

Simon

Its defo oil smoke as you can smell it it doesnt smell rich like fuel smoke at all.

Jez

[Kurgen]

Simon

Its defo oil smoke as you can smell it it doesnt smell rich like fuel smoke at all.

Jez


Are you having to keep topping up the oil.?

[InsBro]

Are you having to keep topping up the oil.?


996 TT's are quite heavy on oil consumption some are 1 litre per 7-800 miles

Mine isnt quite that bad but i do have to top it up, i thouhgt it would be as its quite low mileage.

Jez

[Gastro]

996 TT's are quite heavy on oil consumption some are 1 litre per 7-800 miles

Mine isnt quite that bad but i do have to top it up, i thouhgt it would be as its quite low mileage.

Jez

Thats the quoted allowed tolerance for most 911's isn't it...... it certainly was that in the 964 handbook and in fact its the same for the n/a 996's .........in fact they quote up to 1.5 litres per 1000km :eek: in the handbook that I've got...

[InsBro]

Thats the quoted allowed tolerance for most 911's isn't it...... it certainly was that in the 964 handbook and in fact its the same for the n/a 996's .........in fact they quote up to 1.5 litres per 1000km :eek: in the handbook that I've got...


Yes it is but my 996 C4 didnt use 2 litres in top ups in 13 months and 11k miles

Jez

[Gastro]

Yes it is but my 996 C4 didnt use 2 litres in top ups in 13 months and 11k miles

Jez

......may be your hair rollers at the time explain that - now that your driving a mans car - it needs maintenance ;) :D

[dave blackley]

and the fact I can get the PSM light to flash away in 3rd with the current state of my rear tyres :D

Jez

TYRES :D :D :D

YOU KONW WHERE I AM

[Chris Ward]

Mmm - its confusing isn't it.
The older air cooled's were a little more predictable since a lot was to do with oil passing between the pistons in engines that had relatively slack tolerances.

With the more modern 911/boxster's I'm not entirely sure its oil that causes the 'smoke' - more a rich mixture with a bit of oil (does that make sense ?).

My boxster would do it - but predominantly (not exclusivley) if I did a short journey and then let the car stand overnight to be restarted the following morning........

Does this shed any light on the matter ? Perhaps not :o
Black or dark Brown smoke is Fuel....
anything from white to blue is oil....

[Chris Ward]

Mmm - its confusing isn't it.
The older air cooled's were a little more predictable since a lot was to do with oil passing between the pistons in engines that had relatively slack tolerances.

Also the NA engines don't have the same charge in the cylinder so the piston does not get quite as hot as the Turbo engine...and seeing as the Pistons are made from ALI there expansion rate is higher than the Steel cylinders...therefore the Turbo engines will have slightly larger clearances that the NA piston to bore...

[Gastro]

There you go......... Chris 'Oracle' Ward has the answers...... :)

Are you coming to the breakfast meet matey ??

[Rosco]

Sounds like mine is very similar to yours Jez. I've only had to top mine up once in 2-3000 miles and only occasionally smokes on start up. Main time I've noticed it is when it has been parked for half hour or so. In fact it did it badly when we were at Oulton and I started it up for you. When I came back to it, it chuffed like a bugger! Definately blue! :confused:

[03-turbo911]

This one used to have quite an appetite for oil while running her in but it's much better now. The previous turbo was much better in this regard. The smoke that I keep getting once a week maybe is a whiff of dark brownish coloured smoke, not the usual white/blue smoke that I remember so well on previous 996's.

[InsBro]

Well since I posted this thread today is the first time my car has smoked on startup but only a little

Strange


Jez

[A-Mac]

I would venture that a combination of design [Boxer engine] and being turbocharged are the major contributory factors in smoking on start up.

When the engine stops it must have valves held open, if this is exhaust valve, then some oil from the cam boxes will enter the cylinder in question. Also turbos have sumps and will have oil in the chamber, this may also get burnt up....

Just a few thoughts

Allan

[Gastro]

Well since I posted this thread today is the first time my car has smoked on startup but only a little

Strange


Jez

Maybe its seasonal :o

[A17DY C]

My 996 c4s always smokes when I start it up, is this because it doesn't get used on a regular basis?

[Chris Ward]

Allan is right...

There are about 5 scavenge pumps in the Turbo engine...

1 for each Turbo
1 for each head
1 for the engine

They all feed back to the oil tank....

There is a lot of oil being used by the engine...the vairiocam, turbos and valve lift all are controlled by oil pressure and valves...

There is even small jets that squirt oil onto the underside of each piston when the rev's go higher that 2500 RPM...

The horizontal cylinders are going to have oil sitting in the bore, under the piston...and as Allan says if the inlet valve is open the oil can seep down the valve stem into the inlet port ready to get sucked into the cylinder..

[Chris Ward]

Check this link....

http://www.clw.me.uk/911/brunt2005/bruntindex.htm

Think it's the 19th picture down Black 360 and C4S Cab..

The C4S just started up...and the smoke was really bad...hence the cloud over the 360...

[InsBro]

Check this link....

http://www.clw.me.uk/911/brunt2005/bruntindex.htm

Think it's the 19th picture down Black 360 and C4S Cab..

The C4S just started up...and the smoke was really bad...hence the cloud over the 360...

:eek:

Its never been that bad :D

[StuartMartin]

Mine smokes about 1 time in 20.
Sometimes it is not too bad, but occaisionally there is a huge cloud of the stuff. More than in your 19th picture.
It is oil - you can smell it.
After 1 -2 secs it stops then never gives out anything afterwards.
I don't worry about it.
It is completely random, and is regarless of how long it has been left, how hard it was driven, the weather, how flat the ground is, the day of the week, etc. It has to be something like how the engine stops, i.e. what position the crank stops and what position the valves and pistons are in. This would be random.

I use less oil in the turbo than in the C4S.

C4S was 6 litres in 28K miles.
Turbo is 3 litres in 27K miles.

I ran both in carefully, following my normal pattern.
I am convinced this is the key to any consumption issues. You need to polish the bores and other parts during the first 1000 miles, then open it up over the next 2K. After 3K it is mostly done. After 10K it is fully done until you wear out the pisotn rings of the bores.
I plan to do starship mileages in it, so it is worth me taking the effort to look after it. The first 3K took less than 8 weeks, so I managed to be patient.
Caning it straight out of the box is the main problem.


Oil conmsumption goes up a but if you drive it hard it, so I use a bit more in the summer than winter. But the car only gets used on the road.

[InsBro]

Stuart

As you say it is totally random

Mine hasn't done it since

Jez

[03-turbo911]

Mine stopped smoking a month ago. Maybe I should do the same.:)

[NLW73]

jez

have you spoke to porsche about it? is the car under warranty?

allan's explanation sounds about right and often oil residue can be left to explain the smoke.

I take it it does not smoke at all on the moce as that is when you have to worry. or even when you back off?

[StuartMartin]

Mine stopped smoking a month ago. Maybe I should do the same.:)

It is just lulling you into a false sense of security. It will wait until you least expect it, then when someone is watching will produce a large cloud, just to impress the neighbours and other people in the street what fine shape it is in.

[InsBro]

jez

have you spoke to porsche about it? is the car under warranty?

allan's explanation sounds about right and often oil residue can be left to explain the smoke.

I take it it does not smoke at all on the moce as that is when you have to worry. or even when you back off?


Yes & Yes

They say its a lottery in the workshop sometimes they can go for weeks without one smoking then 2 will do it in one day.


No smoke at all when caining it or when i back off

Jez

[03-turbo911]

Never had large clouds of smoke with any of my turbos,past or present. My '02 targa did it once in a parking building. Had to explain to concerned security personel that they all do that.