Smokey Joe

Hi, Having owned a 996 for 5 weeks I am still getting to grips with all the quirks/faults etc. I took the car to work for the first time, and got the nice car/ flash git comments in equal measure. But the problem was when I left for the day. I started the car and a big cloud of blue smoke came out the back. It has done it once more since. Oil levels good, doesn't smoke under acceleration, and I have heard of this before, but what is it, and should I be worried? Dave

Hi Dave. Looks like you're relatively new to the concept of flat, horizontally opposed cylinders - as opposed to the traditional straight up and down type...? These engines have something called an oil/air separator which can sometimes cause problems if they fail. But the result of this is more like clouds of white, oil-smelling smoke. What I think that you have here is merely what is regarded as 'normal' symptoms of the positioning of the cylinders in your engine. I always get a cloud of blue smoke when my car has been 'at rest' for a few days or weeks. Its because small amounts of the oil in your engine finds its way past the piston rings when you car is stone cold. This is mainly due to the pistons laying flat and the metals being cold and contracted. It's also arguable that the standard 0/40w Mobil 1 oil viscosity (or lack of) doesn't help here either - the stuff is like water. This small amount of oil then ends up in the combustion chamber which then mixes with the fuel that you add with your foot and........BOOOM! Puff of blue smoke out of both tail pipes on start up which then fades pretty quickly(?). So, pretty much normal behaviour for your engine (and all other 996's/997's). Only a problem if the smoke is white, you're using oil and she looks like a steam engine when she's under acceleration / power.

I know, I know, it's normal, but the cloud of smoke I got this morning made the road look like a war zone. It's not a good look. Do all 996's do this or just a select few?[&:]

Mine did it on and off and to varying amounts, also depends if I park it on a slope etc. However since I had a major service mid April I havent noticed it at all.

Yea, had a minor servcie plus brake fluid at Harston porsche, and I didn't see any smoke for 10 days then I got the smoke this morning (after a bit of a thrash last night). It cleared straight away. Just have to hope next years major service sorts it. Cheers Dave

I thought the SAS were coming, the amount of smoke I had this morning. It did it once or twice when I first had the car but since having it serviced I have had two huge clouds of smoke. I notice when doing the oil level check the guage goes right to the top. Could it be over filled. When arrivng at work this morning, I redid the check (24secs) and got the following reading, which is the lowest it's been since the service. My concerns are - 1. It's bloomin embarrasing 2. Will it knacker the CATS

Is it blue smoke, or a huge cloud of white/grey smoke? Does it feel oily to the touch? If it is white smoke, it may well be the Air/Oil Separator has failed. A simple check is to remove the large inlet hose to the throttle body, open the butterfly, and peek inside with a torch. If the internal surfaces are glossy with oily residue, then it is the AOS which has likely split internally.

If it is the AOS, get it fixed asap - mine didnt just split - it exploded, and the engine had to be partly dismantled to clean it before fitting the replacement part ! Chris

Thanks Richard and Chris. Suspect this is the case. And the cost of a replacement? Is it a DIY job, or a book into the garage job? Looks like a nice long weekend doing the discs and the AOS

http://www.renntech.org/forums/tutorials/article/238-air-oil-separator-replacement-aos/ But I think the procedure is different for a 3.6

I think the proceedure is the same. Tiptronics are more difficult, I believe. The part is about £70+VAT, depending on model. Not sure if it is mentioned in that thread, but you can loosen the engine mountings and drop the engine by a couple of inches to give better access. You have to be keen to DIY.

Strange, people always say they get smoke when starting if it is left. I started mine for the first time in four months to get it out for a clean the other week, and it started smooth as anything with no smoke and no noise! Certainly smoke on acceleration isn't normal, it could as mentioned, be something as 'simple' as the AOS, whilst it is a simple bit of kit, changing it is not quite so simple. Hows the oil pressure?

I am planning a weekend of pure porsche fixing fun. I have all the front disc stuff, and will get the AOS tonight/tomorrow. But just before I start removig the intake system and lowering the engine. I want to be sure it is what I think it is. On two occasions I have had a massive cloud of white smoke come out of the back of the car when starting from cold. Instead of the slight blue smoke which I have seen It clears after a minute. The car runs fine, doesn't misfire, and no engine warning lights come on. And subsequent starts, when warm, don't produce smoke. It seems worse after I have been for a quicker than normal journey the night before. And only happened after a service where the oil level gauge showed a level all the way to the top. Tickover does drop slightly, momentarily, when removing the oil filler cap, but I would expect this for a dry sump under slight vacuum. Or am I wrong. Ideas?javascript:void(AddText('[ ]'))

Hope it's not a tip,had to have my AOS replaced recently and it's not a DIY job on a tip,and I did try before having to pay someone.

Did you look inside the throttle body?

I put a long knife with some tissue taped to the end and wiped it gently along the back of the throttle body, and got this. Which I thought was ok. And then I stuck my finger in...

... and this just under (well slighty in a bit) where the butterfly would close... So if this is getting long winded. My Lotus Elised even waited 6 months before my first problem. So I'm still stupidly hoping it's just an oil level issue.

It looks dry, but a bit sooty round the butterfly, which I would say was fairly normal. Beginning to wonder about the AOS failure, although clouds of white smoke is typical. What does the oil level show on the dipstick? If it is above the top mark, try draining some off.

Yep, checked at lunch time, and it appears by looking at the dipstick that the level is at the very top. I took a photo, but it is not very clear. Oil comes up to the waisted area and slighlty above. When I did a dash oil level check, the reading was what it has been since being serviced at Harston.

It certainly is full, but difficult to say how much it has been overfilled. If it was me, I would try to drain about half a litre or so, and check that it comes within the markers. I always preferred to run mine with one empty bar below the max mark, rather than all full bars including the one above the max.

I'll drain off a bit tonight,and save it to top up (due to the cost of mobil one ), and see how it goes. I'd much rather do the front discs this weekend than the AOS.!! Thankyou

Drained off a litre by accident, dropped the sump plug, and I put back just over half a litre. So in reality I removed just under 1/2 a litre of oil. It showed one bar less than full on the electronic guage. I went for a very spirited drive (what a fantastic car). This morning, started the car and ..... No smoke at all. Yippee!!! So I can only assume the technician at Harston typed in the wrong values when setting up the oil fill at service. Just hope I have haven't damaged any seals or the CATs with this issue. The chain tension nut looks very oily at the moment. But still, it looks like I can spend the AOS money on wheel refurbishment.[ ][ ][ ]

still getting a largish puff of smoke at start up now and again (everyother morning). I know peope,have said it happens. But can I do anything to reduce it? Coud it be an AOS on the way out, but not one that had failed. I sorted the mega cloud because of over filling, but this smokey start up I don't like. [ ]

What grade of oil are you using and what are the miles on the car? Alasdair

Can I assume the large clouds have gone completely, and it is a puff of blue smoke you are now getting? What are the circumstances in which you last use the car before parking it up overnight? For example, I know that if I reverse my car out the garage, wash it, and put it back in, I can almost guarantee a puff of blue smoke the following morning. If, for example, you pull your car up to the garage, and leave it there for an hour or two before putting it to bed for the night, you will have a similar situation. As Alasdair is suggesting perhaps, try a 5W-40 oil rather than 0W-40. I also found that made a difference on my 50k+ miles 996 C2.

Yes, it normally sits on the drive after I get back from work, then I put it away in the garage later on. Maybe at the next service I'll go for the 5w-40. The car is a 52 plate Targa, and it has done 73k. On that mileage it's only just run in! I got a puff of whiteish/bluish smoke on start up, and then after about 5 or 6 seconds the exhausts clear and no smoke is visable. I have noticed sometimes that it is one side rather than both, and it's not always the same side. One of the best views is looking out of the wing mirror and seeing the classic 911 wheel arch, just occasionally spoilt waiting for the puff of smoke on start up.

Just to humour me, try putting it straight into the garage when you get home, and see if it still puffs in the morning.

no smoke this morning. But tonight I thrashed the car back from the next village ( 4 miles), and then put it straight in the garage so will see what it's like tomorrow morning.

Yippee, still not a single smokey start up. I think I will still get the odd 'Flat Six' start up, but that I can handle (just). It was the huge clouds that bothered me. I will still follow advice though and use 5w40 at the next service. Thanks for advice/support from all! So as long as I don't get it serviced at Porsche I should be OK...

Couldn't sleep most of last night. My car has had quite a few smokey start-ups recently. One of them, as I left work, continued as I drove down the road for about 200yds. So it got me thinking that maybe a should replace the AOS. I did the " remove filler cap while the engine is running", and noticed that the engine revs dropped and did not idle smoothly. Is this a sign of the AOS on its way out? Normally I'd get about 2 or 3 in a row every 5 weeks, but these seem to be more often. And how much to replace? I looked through the Renntech article, and seems a bloomin long job for a diy'er. And I have to replace the coffin arms, drop links... And I'm not sure I'll have the time for AOS as well, unless I buy another car for work. Would it be any cheaper when having major service which is due? Worried Dave

I've heard a lot of people say about that, but my 996.1 with over 100k never did this no matter how long I left her for. Always a clean smoke free start up, although she did have that rattle / vibration noise for about a second on every start up no matter what the circumstances were.

Another factor in this random smoking, if, as has been suggested by more knowledgeable people than myself, the Air/Oil separator is not on its way out and overall the oil level is not higer that the maximum mark and the engine is in good order, the position of the piston rings on their relevant piston can contribute and is nothing to worry about or anything that can be adjusted. When I used to assemble flat four engines when working for a respected VW engine builder in Surrey we used to start off by putting the gap in the oil control ring at say 4 o'clock, the lower compression ring gap at 8 o'clock (or vice-versa) and the gap in the top ring at 12 o'clock. That way you would have to have serious volume of oil pooling in the barrel for it to be able to find its way past the rings. With the best will in the world you have to think that over time the rings would rotate around the piston and at some time line up just right, then just when you least expect it you get the smoke; then you start the engine and they move again so it can't happen. I am no expert on how much, or whether at all, the rings shuffle around the piston, but it is at least plausible. What I do know is that if you don't position the piston rings as described, the engine smokes like a bar steward when you are bedding it in.

Was it difficult to remove the oil cap - i.e. a lot of vacuum on the filler tube? if so, it could be the AOS. I'm still not clear what colour the smoke is. Blue, black, or white? Does the smoke feel oily when you put your hand next to the exhaust? Is it coming out of one exhaust, or both?

It's more towards white than black. I'll film it when i start it in the morning. I can then share the film. And the filler cap wasn't difficult to remove, but it did make a difference. And it's not always equal out of both exhausts. Ahhhh, I know I'm going on, but I only have a finite budget before the Mrs hits the roof. And I need to pick a choose the jobs I can do. I am still waiting for the right time to do the coffin arms a drop links. The plan is, roof open and a nice blast down to Reims, and retune with a couple of boxes of fizz in the front! So I need to get all the issues fixed.