2 questions. Some fluid level is low, I have no idea what it is, and some vacuum noi

1) I popped the engine compartment and saw that this fluid level was low. I don't know what it's for. It's located on the left side at the top.. Has a max/min level indicator mine was below the min. What is it? What should I fill it with? Available at autozone? Any specific/good brands? What causes it to be low? 2) vacuum noise - sometimes, usually after highway driving, when I come to a hault at the off ramp, I hear the fan/vacuum/noise turn on, sometimes really loud.. Just like how u turn on a vacuum. Them goes away like 5 seconds later - or when I turn off the car. What is this? What's it for? I'm in Philly and its like 30* out.. And my temp doesn't raise past the beginning of the 0 in the 180.. So I know there isn't an over heating issue TIA

1- Coolant tank, anti-freeze. Many would say stick with Porsche fluid. 2-Probably the air pump(forget the name) located at the left front corner.

btw the noise comes from the engine.. not from the front of the car.. i believe back left side. another question - what causes antifreeze to decrease in volume? does it get used up? burned?

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Left front corner of the engine area, NOT the frunk.

It leaks. Hoses, coolant tank, water pump etc. Do you smell anti-freeze ?

oh okay... but why does the fan come on when the engine's not hot? also i dont know what antifreeze smells like, but i dont notice any new smells since getting the car (i'm already used to the burning porsche smell that comes after hard driving)

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may need to check your t-stat. And as Barn996 already suggested: also check the coolant reservoir, cap, hoses and water pump

I think these 2 could be related issues. As others pointed out, the tank is for the coolant. If the level is below the min level, it definitely means low coolant. Do you have the red LED at the end of the temp gauge blinking when driving? If yes, then the car is aware of the low coolant level. Even otherwise, since you saw that the level was below the minimum, there definitely is a shortage of coolant. There could be a leak somewhere in the cooling system (if its an old car, it mostly is the coolant tank or its cap) In either case, if there is a leak, you'll probably see the stuff dripping after your drive - check under the car after parking and switching the engine off. The temp. gauge measures the temp of the coolant coming out of the engine. So if there is less coolant, chances are that the sensor doesn't have enough of the stuff to give a proper reading. This would be my guess. As for the fan noise - I believe this is the engine purge fan that kicks in when the temperature of the engine is higher than normal. The fan doesn't run for long durations and comes on intermittently. This could be related to the low coolant levels you have in the car. Or, as pointed out by kromdom, it could be the thermostat that's off by a bit. DO NOT pour in any antifreeze in there. Even if you buy Porsche antifreeze/coolant, there are multiple ones out there (green, yellow, pink) and there could be a potential gelling if the varieties aren't compatible. Your best option would be to fill up the coolant expansion tank with distilled water. Upto a gallon or maybe even two should not change the concentration a lot. Beyond this, I'd probably suggest an inspection of the cooling system - tank, tank-cap, hoses etc for leaks. In case you've lost a lot of the coolant, it would be best to fix the leak and replace the coolant in the system completely. I recently had a low coolant issue and the culprit was the tank. They do tend to wear over the years and develop cracks. In such cases, you'll see leaked coolant dripping on the drive side exhaust and onto the floor.

Take the car to someone that knows what they are doing.

Assuming your car is a 996 Porsche: You don't say whether the engine was hot or cold when you noticed the low coolant. How low was it? 1. Check the part number on your blue coolant tank cap. If it doesn't end in -04 buy a new one from Porsche, less than $20. -04 is the 3rd and latest generation of these. The older ones tend to fail. DO NOT REMOVE IT WHEN THE ENGINE IS HOT!! 2. Most likely your Secondary Air Injection Pump, it comes on the help light off the cats and keeps the cats hot. Almost always for ~12-20 seconds at first start. It will also come on under other conditions when driving. This lives in engine compartment near your left knee when you are standing gazing into the engine compartment

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I wanted to say this earlier after reading the OPs opening line: Have your indy do a "pressure test" of the cooling system, hopefully to pinpoint/locate/identify the cause of your "disappearing" coolant.

yes car is a MY03 C2. I was checking it in the morning in Philly (ambient temp 28*F). The secondary air pump does go away after like 10-15 seconds. I've been reading that it's normal. I'll look under my cap today.. actually now lol and will update soon. distilled water... same as mountain spring water for drinking? or should i get the kind that says specifically distilled... and why not just buy the antifreeze that's supposed to go in there anyway?

Grocery stores have distilled water in gallon jugs.

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Distilled water is best. "Mountain spring" water may be tap water in a fancy bottle and could evem have minerals added to the water. You can add Porsche anti-freeze but not many have a jug of it laying around. I have but have used just a few cups from the jug since buying it years ago. Generally I just add distilled water when the coolant gets low and every time it has gotten low there has been a leak in the cooling system. First time was due to a coolant cap, the second time due to a crack (split) in the coolant tank. There's a concern that in adding water this will raise the freezing temp of the coolant so adding distilled water is a temporary solution to a low coolant level. The reason the level is low needs to be found and fixed and the coolant topped up with anti-freeze to ensure the coolant has sufficient anti-freeze protection for your location. In the case of the tank repair the tech just drained the system, replaced the tank, and refilled it with fresh coolant. If the coolant is fresh the system doesn't have to be drained completely, just enough that the level is below the tank fittings. Of course after the new tank is installed the system must be refilled/topped up. This is best done by a vacuum system to ensure complete filling with no air pockets.

I think mine does a similar fan thing to what the OP described and it is not the SAI pump. My SAI pump comes on first thing at first start, then goes off after up to 30 seconds, the noise is fairly high pitched and actually has a bit of a squeal to it. I then drive to my kids preschool, almost always stop at 2 lights within 3 miles. then accelerate and slow back down after another mile at the third light. (I almost always miss all these lights due to the nature of the intersections). At that third light as soon I come to a full stop a fan comes on. It is NOT the same sound as the SAI. It stays on for about 5 seconds then goes off and is not heard from (or noticed) again until the next day. When I vary my routine and go somewhere else (like on the weekends) I have not noticed it. It's weird and does not seem like anything to worry about but I was curious what it was.

Its the same for me WalterRohrl, starts when i come to a halt, goes off after 5 seconds.

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Ok, mine's an '02. I am fairly certain it is not the SAI pump. But it only does it once a day as far as I can tell but after driving for a bit and in my case the third stop. It COULD be that that is when the T-stat is fully open, that's about the distance it takes for the water temp to be warmed up if I think about it. That would make sense as to why it only does it once. My coolant level is fine, BTW. I don't usually have two completely cold starts in a day as I work from home. Take the kids to school, run errands, come back and do various things without letting the car sit all day long like if I worked a normal office job.

SubZeroX, Please listen to those who have suggested that you use distilled water and not any other brand of antifreeze to top off your coolant. We have had a jillion threads on this over the years and the conscensus from the truly knowlegeable is that the Porsche antifreeze is a unique chemical mixture and does "work or play well with others" when off-the-shelf antifreeze is added to the system. Yes, it could be as simple and cheap as just needing a new coolant cap. They do fail. You will need the Porsche-specific cap, and yes, the serial number should end in .04 to be the latest update. For anything else, go to a Porsche certified mechanic for trouble shooting. The description of the fan motor running sounds very much like the SAI motor. It runs randomly when the engine is either cold or very hot. That is the motor still running when you walk away from the car after being very hot. My temp gauge also reads on the left side of the 0 at this time of year. That is not a bad thing.

yea i added distilled water.. thanks guys!

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You sure it is not the secondary air injection pump? It can come on after cold start if the DME determines the converters need extra air the air being injected into the converters directly. I've never heard it come on but it could be with your type of driving early on a cold morning... is your route downhill?

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Hi Macster, My route is pretty flat with a slight downhill (gentle grade) just before the third light at which I hear the fan come on. Similar to the slight downgrades you get out there in Livermore, nothing "steep" at all. At the second light I make a right turn, then on the gas fairly hard up to about 50mph, then I let up as I pass the police station (heh heh), then I kind of coast on light to no throttle to the third light down the slight grade. My SAI pump makes a quite harsh sound, almost a high-pitched metallic scraping noise (more of a "zinging" noise like a rotary saw blade), the noise I hear at the light is very different, more like what you'd expect a cooling fan to sound like. I suppose it could be a pump but only if there are two components to the SAI and only one of them runs at this time as opposed to the two at startup. I don't think this is the case having dealt with an SAI on a Saab previously, so I believe I understand what/how they do in general. The mornings ARE cold, often in the 20's out here since I've noticed it. (same as the OP, I think) I don't consider any of this a problem, I was only trying to point out that the OP very likely could have two different noises as others suggested the SAI for him and based on my experience I did not think his noise was the SAI pump (only due to the fact that I can detect two very different noises (SAI and then the later mystery noise)). Not sure if that made sense but the OP did respond and said that his noise was different from the startup SAI noise as well. I'll keep listening and will report back if I can think of anything else...

There is a fan on the engine lid compartment for cooling the engine compartment. I'd think that would come on only when the engine is hotter that the front fans can take care of.

It would be an interesting experiment to unplug the lid cooling fan to see if that is the 2nd fan noise at the 3rd stop. Odd that it would come on after such a short drive in cool weather. For the OP. My expansion tank likes to stay ~1/8" below the Min line when cold. I can top it up to Min, when cold, every week and drive myself crazy obsessing or just let it sit at the 1/8" low for months. It shows Max when hot.

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Walter you may know this but the rotary saw blade sound is not normal. This is your SAI pump starting to wear out. They normally sound more like a vacuum cleaner. If you can stand the sound it won't hurt anything however and you can use it until the pump eventually fails. Mine was doing the same thing so I replaced it with a $150 used one off Ebay. Takes about 20 minutes to do the job.

[QUOTE=fpb111;10117985]It would be an interesting experiment to unplug the lid cooling fan to see if that is the 2nd fan noise at the 3rd stop. Odd that it would come on after such a short drive in cool weather. I'll try that one day next week when I start taking the little guy to preschool again after concentrating on the noise the first few days. And I will report back... Thanks!

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Thanks for the info, I didn't know for sure but suspected it, the noise is a bit extreme to me. I'll start looking around for a new one. Weirdly enough I got a check engine light today after about a mile or two of driving. The SAI did come on but maybe it is really close to dead. Code reader is ordered and on the way, will report back with the code. Car drives just fine (as it would with a dead SAI) but the code could be many other things of course. I won't replace anything until I know for sure which code...

Some folks have "rebuilt" the $AI. As I recall it was mostly cleaning the impeller(s) and light lube of other parts. Or if that doesn't work pay $1800 for new Porsche box with $300 Bosch part in it (or just buy the Bosch Part in an ugly Bosch box) http://www.autoatlanta.com/results.p...605%20104%2000