Blue Smoke at start for 5-10sec.

Hello, When I start the car (C2, built in 99), I have blue smoke coming out of the exhaust for 5-10 seconds. Unfortunately, this happens all the time and cannot be attributed to the typical boxer smoke. It alternates between right and left. Currently, however, it is preferentially on the left. The oil consumption is relatively low, but I have only driven 300 km since the symptom appeared. When I turn off the oil cap, the car dies. Is this normal, that the car dies? Actually, the oil separator should continue to close when this occurs and the car should continue to run, shouldn't it? I am a little confused. Unfortunately, I don't have a pressure gauge to check the vacuum and I don't change the oil separator on the car just for fun. If I get a pressure gauge, what vacuum can I expect with a correctly functioning separator? Are there other possibilities for correct diagnostics? Thanks in advance guys for your help Youtube Video: You Tube

If the engine dies it's safe to say the vacuum is too high. If you need to really pull on the oil cap after you turned it to get it off, then that is another indicator. If you have the material lying around you could make your manometer: https://sciencing.com/make-own-manometer-5241146.html (use tea or black coffee to colour the water) A plastic glove could work to connect it to the oil fill tube in an airtight manner. Further worthwhile reading: https://rennlist.com/forums/996-foru...by-test-2.html Edit: engine sounds different from my 99 c2. I think I hear piston slap. Consider endoscoping your engine https://youtu.be/2wY_4JPOeKo

Agree with hardtailer. That clicking noise is not normal.

If you aren't project inclined like me to build something from scratch, you can find this manometer or one like it on amazon. You just have to source the oil cap at your dealer and plastic tube and connector at you local hardware store. Pretty good chance you have a failed AOS which is extremely common. Smoke and inability to remove the oil cap easily is a pretty good indicator. Manometer will give you more accurate confirmation. This is an easy fix. My suggestion is you go with the UAOS track version even if you don't track the car. You won't ever loose any sleep again on the aos. But before you start spending alot of money on parts and labor, you may want to consider doing the following to check the condition of your engine. Imho, every 996 owner should go thru this exercise. 1. Test your oil to see what the bits in the oil tell you. 2. Drop your sump to see what's in it as well as check your oil filter as well for bits. 3. Scope your bores from the sump to check for bore scoring. Once you know the condition of your engine, you can make decisions on next steps as to where, what and how you want to spend money and time on the car.

Thanks, guys. The car was in a garage and my dealer told me the noise is supposed to be the hydros. You don't hear it anymore after a minute or so of running. I can't believe it's normal for the car to stall when you open the oil filler cap.

From your stated symptoms, its very likely to be a cut and dry case of failed aos. Afaik, nothing else can cause a large vacuum leak enough to stall the engine when taking off the oil cap, (like you said above).... If your car dies when taking off the oil cap, that shows a massive vacuum leak into the crank case. With the oil cap on, the engine is direct sucking in oil, NG. Typical of aos failure. That leak is pulling in oil to the intake causing very bad things that can happen, like 'hydraulic cylinder lock' totaling your engine. Bending rods, shattering pistons, etc.... My advice to you, do NOT drive the car till it is fixed. A locked up engine is no fun and very expensive to fix. jmho

FYI, my 3.4 ticks like that upon initial start up, but goes away in about 5 seconds. It's done that the whole 16 years I've owned it.

There are 3 major areas of sudden catastrophic failure for the M96. All are easily prevented with readily available solutions. 1. AOS - Best case you get a little smoke. Not so good case you get alot of oil sucked in and hydralock occurs of which the top of your cylinders shatter. Can be easily fixed with a better than oem aos like uaos. 2. IMSB - well documented problem that can be easily fixed with the LN Solution or Retro. If you want a one and done solution that's permanent, go with the solution. If you want a solution that you will need to replace again in 7 or so years, get the Retro. 3. Water Pump - eventually the plastic fins fall apart and plastic pieces get lodged causing excess heat and engine cracking. Just replace your water pump every 5 -7 years and you won't have to worry about it. There is also a slow death by bore scoring which is also preventable and manageable. All you have to do is... 1. Run good oil and change it 2x a year to keep it fresh. 2. Make sure you are running good fuel. 3. Keep your fuel injectors fresh, as well as make sure your coils, spark plugs, Maf and oxy sensors are in good shape so the computer can do its job properly. These cars are pretty simple to keep running at peak performance. Just like anything in life, you just have to prevent the problems from occurring with a few procedures. Good news in the grand scheme of Porsche ownership, it's pretty inexpensive versus other 911 models.

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Yup. I've got a 3.4, 2001 and a 2002, 3.6. Both with around 35,000 miles. The 3.6 starts up quite, no tick, no rattle, just smooth quite purr like a kitten from the instance it kicks over. My 3.4 cold start ups with a rattle/tick/whatever you want to call it, for only a second or 2 then its gone and just like the 3.6 purring along quite not missing a beat... IMO, the noise heard on 3.4 cold start up is cold start '5 chain rattle'... very common on the 3.4 and not as common on the 3.6 3 chain. My 3.4 cam deviation is well within specs, never had any debris in the sump. Eventually I'll check the chain pads for wear/replacement, might be worn, but its done this forever as has other 3.4 I've heard... Lots of chains, tensioners, actuators, pads, etc, on the 5 chain 3.4. As long as we're on the subject...IMO the 3.6 is a better motor, more advanced with some basic 3.4 shortcomings fixed, but still the 3.6 has the well documented problems all m96 suffer from with a few more of its own. jmo

Mine too! Been that way for 6 years. If I drive the car immediately, it doesn�t do that.

stops after a short time? AOS. Here's mine when I bought it with bore score and piston slap. It was a constant smoke cloud... https://youtube.com/shorts/1268A-rKf1Q

I typically drive mine everyday to work. However if it sat for a week or more then I would get a nasty tick on number 4 upon startup. After tear down, I noted that one exhaust lifter on number 4 was squishy (I could compress the lifter with my fingers) where the others were solid as a rock. I replaced that lifter during rebuild and will see if that symptom disappears. Note that I did not have bore scoring - yet.

A quick update from me: I have replaced the crankshaft ventilation and it really does not smoke anymore. The hydro tappet rattle has also all but disappeared as a result. Whether and if so, why this is so, I can not explain.

Did it resolve your vacuum at the oil cap or does your engine die when you remove the cap still?

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What do you mean crank shaft ventilation ?

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I assume English is not his primary language, I think he meant to say " positive crankcase ventilation" ( PCV) .....or as we say in Porsche speak ....aka AOS .......

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Thanks for the update! I'd say your hydraulic tappets were fine the whole time.