CaymanPower

Hi,

I've posted the exact same question on the 987 forum but with no luck. I hope that someone here can help me.

I'm trying to figure out if a bad AOS in the 2.9 Cayman can leak some coolant, provided that there is a coolant line running through the AOS to keep it warm, as it is the case with the AOS from 996's (hose 12 and 13 are coolant).

If the DFI 997 Carrera is something to go by then the 2.9 Cayman AOS will look like this:

9A1 AOS

From this diagram it seems to exist an additional inlet (the smaller one) to the "Oil mist separator"(5) , possibly to carry coolant. Anybody know for sure?


Thank you!

Edgy01

What's an AOS? Air-Oil Separator?

CaymanPower

Hi Dan,

Yes, it means Air-Oil Separator. Upon closer look at the so-called AOS diagram I think the only coolant that runs through the AOS does it so by running through the integrated heat exchanger(4). So, I wonder if a slow coolant leak in one of the seals(6) was present that would explain why I had lost 6.3 quarts of coolant(with no clear leak evidence) and also the ever-present cloud of smoke on cold start-up, by means of overwhelming the Oil mist separator(5) with excessive water vapour, provided the AOS is the same that goes into the 2.9 Cayman. Can anyone confirm this? Also, do you think it would be likely to have coolant on the oil (which wasn't the case when I changed the oil)?

Edgy01

The loss of 6.3 liters of coolant is no small problem. It's a big deal. This is a new thing on me--that there is a coolant route through that device. (for cooling or heating?)

You would immediately tell that you had coolant in your motor oil by the milk shake appearance of it (particularly with that sort of coolant loss). That's good that you don't have that symptom.

Any seeps along the bottom of the water pump?

Crack in the coolant reservoir?

Bad coolant cap? (Usually the most common).

gpjli2

I might be worried about the integrity of the cylinder heads. Cracked head would cause similar symptoms. An experienced tech should check this out imo.

simsgw

I agree. Cindy's NSX 3.2 began showing sudden temperature swings up and back. I shut down and had it towed to the dealer. Head bolts were pulling out of the aluminum block on one bank and that caused the head gasket to fail. We hadn't begun to show white smoke yet, but probably because I got lucky and spotted the gauge gyrations on the first trip after the gasket failed. That would have come next.

Gasket failure or a crack in the block or head isn't the only way to cause those symptoms of course. It is just the most expensive cause of all if you don't get an early diagnosis.

[Edit for an afterthought: This sounds like the NSX was the only time I saw that. On the contrary, I knew to shut down because I saw it several times in my high school days when I seemed to go through hundred-dollar cars twice a year. That's how I knew enough to shut down immediately in an exotic. You can't get near that repair job on one of "our" cars for a hundred gold doubloons of antique quality, never mind dollars.]

Gary
Who wasn't too upset, since we had 100,000 miles
on that NSX, but would have been downright pissed
if we had lunched the lump and had to replace it

CaymanPower

For cooling I guess...


Dealer did a 2-3 hours (not an overnight) pressure test and no leaks were found. Visual inspection to the engine and underneath the car (without taking off the bottom plastic covers... a big no, no!!!) revealed nothing.


I never observed any temp oscillations, but I've never reved the engine above 4000rpm's (since I've first saw the exhaust smoke on start-up) either. Also, the coolant light never came on, why???


Gary,

That is what I'm afraid of...


gpjli2,

I only got the smoke out of the tailpipe on cold start-up's, sometimes a LOT of smoke. In the event of cracked head shouldn't I always see it? How can I tell if a cracked head is present? Compression test?

Macster

Do an oil analysis. If anti-freeze chemicals present or more than a few tenths of a percent water turns up from the analysis there's a problem.

No need to do a compression test. Pull the plugs. If the engine's going through that much coolant you'll see one (or more) very clean spark plugs.

Even this I think unnecessary. That much coolant I believe the engine would be misfiring and you'd have a check engine light (maybe flashing) and misfire error codes.

Some smoking -- oil (and if cold a bit of water vapor will present in the smoke as well though this water vapor takes a few seconds to develop while the oil smoke's there from the get go) upon startup is normal. A few cars do it a lot. There are some who advise to give the engine time -- 10K miles maybe more to fully break in -- before reacting to smoking absent any other symptoms. In this case you need to figure out where the coolant is going that's for sure.

Be sure the oil level is not too high and the oil's reasonably fresh and of the right type. None of that 5w-20 stuff! Use a high-quality name brand 5w-40 or Mobil 1 0w-40 oil, any oil that meets the requirements for oil Porsche sets forth in the owners manual.

With no coolant puddles under the car and a clean water pump -- no white stains -- I'd suspect the coolant cap. They have been known to leak and lose water vapor and lower the coolant level to the point the coolant warning light flashes.

Sincerely,

Macster.

CaymanPower

Hi Macster,

Let me try to clarify the whole situation:

1) Car was bought used from an official Porsche german dealer with 9942miles;

2) Manual tranny replaced at 9817 miles under warranty, ONLY FOUND OUT TODAY!!!

3) I only did 403 miles with the car;

4) Whitish-bluish smoke (sometimes a BIG cloud) on every cold start-up;

5) Too low coolant level checked on the coolant filler neck marks;

6) Coolant warning light never flashed;

7) Coolant temperature gauge always acted normally;

8) Needed to top up with 6.3 quarts of water;

9) Pressure test, no leaks;

10) Coolant level ok ever since;

11) Changed oil, normal apperance;

12) Engine not revved over 4000-4500 rpm;

13) Engine runs and starts fine (but i'm new to it);


So, my main concerns are:

1) Could the tranny replacement have anything to do with the low coolant or smoke on cold startup?

2) Would it be necessary to mess with the engine cooling system for a MANUAL tranny replacement ?(pull down the engine is not needed)

3) What happened to 6.3 quarts of coolant?

4) Were they there, to start with?

5) Why didn't the coolant warning light flash?

6) Did air get trapped in the coolant lines because cooling system wasn't flushed/filled properly (tranny replacement)?

7) Why there is a whitish-bluish smoke on every cold start-up?


If someone has a reasonable explanation to those 7 questions, I would be a, very, VERY happy man...

simsgw

To be honest, I'm an engineer with 45 years experience and I've been a car enthusiast since about 1956, yet I can't begin to answer those questions without having the car at hand, a service manual, and a wall full of Porsche tools. If I had my druthers, a master mechanic to use them would be nice.

All I can say is they are very good questions and Porsche should answer them for you without hesitation and without charge. Let me add a few to help us understand the situation:

1. You say a German dealer sold you the car. Are you still in Germany or did you bring the car back with you to another country? If you're in the United States, it sounds like time to call PCNA and get them to identify a dealer to diagnose the situation for you and them.

2. Do you have warranty coverage? At this mileage you should have unless the circumstances are passing strange.

Now another question for you and Porsche to figure out:

3. What incident required the transmission replacement? You need specifics because many such can damage the engine as well. Most of them I would say, unless the driver has the reflexes of a fighter pilot or a race driver. Whoever took the car in and did the replacement presumably ran some tests, but they don't seem to have revealed all the problems.

Incidentally, as long as I mentioned 'whoever' it must be said that certainly a transmission replacement could cause other problems. It should not, but it is also true that proper examination of the car when deciding the change was needed should have revealed these problems as well. Once we identify or presume incompetence is at work, then other sorts of mistakes are quite possible.

My best guess at this point is that whoever bought the car and passed it on to the dealer who sold it believed an explanation of the transmission problem that did not involve the engine. Accepting that explanation, they replaced the transmission only and did not look as hard for engine problems as they would if they'd known what really happened. We might also suppose they were hoping to get rid of the car before engine problems showed up, but I find it easier to assume good faith in such cases. As with incompetence, once you assume a crook is involved, then anything is possible. Obviously, the dealer who sold the car to you might also be the one who bought the car from the previous owner and changed the transmission, but we don't know of course. You might, but I don't.

Assuming good faith makes no difference to your situation. Either way we can expect PCNA or your national Porsche agency to find a way to resolve the situation for you.

I highly recommend you get a top dealer involved, but before you do get hold of PCNA or the appropriate agency for your country. This could be something trivial, but when you know the car's been abused in some way, you need to assume the worst until reassured by a master mechanic. Your car needs a serious examination, not garage tinkering following suggestions by a bunch of friendly folk thousands of miles away.

Good luck,

Gary

CaymanPower

And what a bunch of good folks you are! Without you I would have never learnt half of what I did... and that goes a long way to what ownership is all about. Thank you!

Gary,

You are absolutely right. In fact, my car has been at the dealer almost every time since i've been asking around. It's the second dealer I go to, and it was this one who told me that it had been a tranny replacement. Unfortnately, i don't have a national Porsche agency here in Portugal. The car was a dealer's demo and it was imported from Germany to Portugal (I didn't brought it myself and didn't see it live until the car arrived to Portugal). Tranny was replaced by the german Porsche dealer. Obviously, I wasn't told about it and there's no service history about it either on car's service book. Only dealer(portuguese) could see it on Porsche central database by car's VIN and that's how I knew about it. It's very difficult to me to assume good faith in such cases.


That's precisely what i'm trying to figure out. Of course i've asked german Porsche dealer about it and i'm waiting for their awnser. Meanwhile, i've been trying to do my own parallel research in order to be prepared to what dealers could say and not be fooled by them. In following that trend, I would like to ask you to be more specific about what you mean by «You need specifics because many such can damage the engine as well. Most of them I would say, unless the driver has the reflexes of a fighter pilot or a race driver.»

I'm not following the "reflexes" issue here...

On a side note, I can add that no oil in coolant and coolant in oil was found and no bubbling or coolant "explosion" due to combustion gases pressure were present when opening the filler cap.

simsgw

With that information I agree. We can't be sure who the thief is in that chain of events, but someone is.

One example, though I could list several. One quick way to ruin a transmission is to hit first when leaving second gear at the redline. That is, you reach for third and something diverts your hand or you simply make a mistake and hit the gate for first instead. This rarely happens in normal acceleration, but when you're running up the gears quickly at full acceleration, it can happen. The transmission does not willingly go into first with the terrible speed mismatch. The engine is at redline in second, the car is going nearly seventy mph (about 110 kph), depending on the gearing of the model, and the synchros will be very stiff.

I did this once when taking a very tall man for a ride. A guy well over two meters. A client, so I couldn't even use the language his actions deserved. As we came around a cloverleaf freeway entry accelerating to match speeds, ahead of a bloody cement truck coming down a steep hill for all love, he leaned his knee to the left (to resist the side loading) just as I grabbed for third gear. Nothing slowed my forward hand movement, but he deflected my hand just enough to hit the gate for first.

Several things may follow this event. Since the synchros resist the engagement, it is likely the gears will engage only partially. That puts the sudden torque load on half a tooth, which is what happened in my case. It knocked off a small part of several teeth. (More technically, for those who speak English geek, I caused spalling on the tooth face of several teeth in succession. Afterward, it worked but boy did it sound bad.) Even if you fully engage, the transmission is still absorbing a tremendous torque overload as the engine resists sudden acceleration to perhaps 14,000 rpm. The transmission from a lesser manufacturer might well damage shaft bearings at that point. Porsche builds transmissions we might call "hell for stout" so I wouldn't expect this particular problem though it is possible. More likely, it just causes problems on the pressure face of the gear teeth. Those may be disabling problems or just ones that make it intolerable to continue using the transmission without repair or replacement. That's what happened in my case.

Finally of course, the rest of the drive train is under a sudden overstress situation. The wheel bearings and axles on most cars will not see more than they are designed to handle but the clutch, flywheel and the engine internals are looking into the mouth of mechanical hell.

At that point is where reflexes come in. I couldn't slow my hand from engaging the gear and besides, like most pilots and race drivers, I am always affirmative with control movements. I use no more force than necessary, but my reflexes are programmed to use no less either. That is, if I reach for a gear or if I intend to move an elevator, that control movement will take place no matter what resistance I encounter. Even if I regret it milliseconds later. Our training teaches us this "gentle but firm" method, but I'll bet your instinct is to do the same thing when hurrying through the gears.

So I got the transmission -- nearly at least -- into first gear while going twice the redline speed for that gear. And of course the clutch being engaged is a matter of timing and comes within a tenth second after the gear engages. But I knew it was wrong almost as quickly. The passengers registered only a loud bang when the clutch engaged, but I had my foot disengaging it before they knew anything happened. We figured afterward that the clutch was engaged less than four hundred milliseconds. Probably much less. The inertia of the flywheel protected the engine. It never even went above redline, though it was within a couple of hundred rpm when all this happened.

That is how reflexes matter in these cases. They keep the consequences of a wrong action from propagating to other parts of the equipment. Not just speed of reaction course. You have to do the right thing. Disengaging the clutch in this case. Training provides the educated response. (Small endorsement for DE days slipped in there, you notice.)

If you think it is quick to do all that before the engine could accelerate two hundred rpm, you should see how fast a pilot in a twin-engine aircraft can hit full compensating rudder when he senses failure of thrust on one engine. Well... I speak of the live pilots of course.

Back to your issues. If someone managed to damage the transmission and wasn't as quick as some of us are, or wasn't as lucky, then he might well have done things to the engine we can't even guess at. I'm glad you're working with a dealer, but even if you don't have a primary agency for importing Porsches in Portugal, let me suggest you contact Porsche directly. They will have an international number for customer support at the factory. If you can't find it, let me know and I'll dig it out for you.

If this is a minor problem, then fine. But either way, you need to have Porsche involved from the beginning. You should be covered under warranty. I can't see any argument whatsoever against it. So handle this correctly by letting Porsche be involved from the beginning to minimize their cost for doing the right thing by you.

Gary

CaymanPower

Thank you very much for your explanation and help. The thief here is the german Porsche dealer because they omited that a tranny replacement took place. Clearly, this is NOT a good sign. I'm going to wait for what the german Porsche dealer has to say and then I'll act accordingly. The two portuguese Porsche dealers i went to keep saying that they haven't found anything wrong with the car and that the smoke on start-up is normal. The first portuguese dealer even showed me a TSB from Porsche regarding bluish smoke on start-up for all Cayman's MY09 (i actually saw it). So, Porsche acknowledges that there is an issue with the smoke on start-up from these engines (2.9 9A1) MY09. The TSB consists of an ECU software update. My problem is that this update didn't solve the smoke issue, which is, if thruth to be told, the ONLY bad symptom that the car presently have. Everything else seems normal to me. The best explanation that I can come with for the coolant loss is cooling system not porpely flushed/filled somehow when they did the tranny replacement and then air got trapped in the coolant lines, which 'tricked' the low coolant warning light. And, only when I opened up the coolant filler cap the air manged to escape(as it is always happens) and i saw no coolant in the filler neck. Even though that would NOT be good! But then again, although based on all the evidences I could gather, I'm just guessing because Porsche dealers are keeping saying that the car is normal. How could it be?

1) A cloud of smoke on every cold start-up?

2) A TSB that didn't work out?

3) A big quantity of coolant that was missing?

4) A coolant warning light that didn't flash?

5) A tranny that was replaced and I wasn't told about it?


Which is normal?

Macster

Let me see if I can respond with anything of value.

1) The car is what it is, not what it was.

2) This might be significant. Keep reading.

3) You're not driving the car enough.

4) This could arise from several things: 1) Oil overfilled; 2) Oil "old"; 3) Oil of the wrong type, viscosity.

Let me digress and cover this more thoroughly: Overfilled oil or old oil which is contaminated with water/unburned fuel which makes it more prone to aeration and increases oil vapor content of crankcase fumes. These fumes can overwhelm an AOS and thus send lots of oil vapor to intake manifold and this can result in smoking upon startup maybe every engine start. It doesn't help that you have apparently not driven the car much. Short trips, idling, all help to load the oil with water/unburned fuel.

5) Does the smoke have an anti-freeze smell? If so there could be a coolant intermix problem. You can have some oil removed and analyzed looking for any anti-freeze chemicals. But if intermix bad enough to lower coolant level just draining the oil in a clean drain pan should have any water visible.

6) Won't flash if coolant level not low enough. (Assuming coolant level sensor working. Worry about this later.)

7) Coolant gage pretty much useless for detailed coolant temperature monitoring.

8) That's a lot of water. It is leaking out somewhere. Maybe. See below.

9) Pressure test done cold, probably. A leak, if there is a leak, may only appear when engine/cooling system hot.

10) You haven't driven the car enough to get it hot enough for the leak to make its presence known.

11) That's good news. The coolant leak likely not an intermix problem.

12) Well, until you get things sorted out it doesn't hurt to watch rpms.

13) That's good news.

Ok, for your concerns:

1) Maybe. Maybe not. First job is to figure out what's wrong. Worry about what caused it later.

2) If shop didn't know what it was doing and disconnected coolant hoses, drained coolant or damaged engine or sensor wiring. After you figure out what's wrong you'll likely know the answer to (1).

3) Leaked away. If there is a leak.

4) Who knows? Have to assume so. Though I hope when car was bought as part of check out vital fluid levels were checked and found to be good.

5) Cause low level sensor may not be working due to several possible reasons. Does the light come on when you turn on the key and go off when you start the engine? Maybe the bulb is burned out, or missing.

6) Possibly. In fact, this might explain the low coolant now that I've worked this far. If for some reason the coolant was removed and the cooling system may not have been refilled completely. In fact, if shop mistakenly drained coolant I'd not trust the shop to know how to properly replace the coolant.

7) See comments under (4) in top section. If oil level ok, if oil type and age ok, then engine many need to be driven more, and given more time to break in. I've read posts where engine smoking is frequent (and oil consumption rather high) for sometimes 10K miles or so. Somewhat depends upon how car is driven. The engine once warmed up needs to see some load and rpms to help fully seat the rings.

Also, you can help by running oil level a few bars below full. And at end of the a trip give the engine a moment or two to idle before shutting the engine off.

Sincerely,

Macster.

mhm993

All of these cars make a puff of smoke, to some degree or another, on cold start ups. Oil gets stuck in the cylinders due to the flat engine design. Not to say your puffs don't indicate a different problem as well.