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I have a 2003 996 Carrera cab.  When I got to work this morning I noticed coolant flowing from rear of engine compartment. The temp gauge never peaked, and none of the idiot lights came on. Any ideas on what this problem is would be greatly appreciated. Thank you in advance

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I have a 2003 996 Carrera cab.  When I got to work this morning I noticed coolant flowing from rear of engine compartment. The temp gauge never peaked, and none of the idiot lights came on. Any ideas on what this problem is would be greatly appreciated. Thank you in advance

 

Either a bad water pump, leaking coolant fill cap, or a leaking surge tank; in any case, not a good thing.

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Does "not a good thing" mean engine damage, expensive repair, or something else? I understand why a water pump would be expensive, but could someone explain why a leaking coolant fill cap or leaking surge tank are bad news? Please forgive my ignorance on this subject. Thank you

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The coolant only works properly if it does not vaporise.  The coolant system on a vehicle is sealed so that it cannot vaporise.  As a result when the coolant becomes hot the system becomes pressurised and it cannot "boil".  When the system is hot, if you were to open the coolant cap you would release this pressure the coolant would boil.   The car normally runs at about 80 deg C (176 degF).  Normally at this temperature coolant vaporises, but as it held under pressure it does not.

 

If you have a leak the coolant cannot be pressurised.  Therefore, where there are hot spots in the engine there will be vapour spots where the coolant will not work effectively as it cannot dissipate engine heat.  Eventually, these hot spots will result in engine damage as in these locations the temperature of the engine will exceed its design tolerances.

 

In a Porsche the cooling system is complex and the coolant is required to travel long distances to get to locations where it can be cooled. With vapour in the system this will not happen. 

 

The advice you have had is sound.  You need to get it fixed and it were mine I don't think I would drive it.      

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Does "not a good thing" mean engine damage, expensive repair, or something else? I understand why a water pump would be expensive, but could someone explain why a leaking coolant fill cap or leaking surge tank are bad news? Please forgive my ignorance on this subject. Thank you

 

By "not a good thing" I mean that you need to find and fix the problem before driving the car.  These engines do not like being overheated, often the first event of this type is the last for that particular engine.  Find out what is wrong and fix it, even if that means having the car flat bedded to a shop..

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I don't know if the model year 03 is included ... but cracked (along the bottom seam) coolant tanks was a common problem on t he early 996s. There were numerous DIY's posted covering the replacement of the tank. I did it ... and considered it an involved ... but not impossible DIY.

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If it went all of a sudden more than likely it is the small plastic fitting on the coolant line that runs from the coolant pump to the AOS.  It is right in the center just to the right of the alternator and the oil filler tube.  I hope it is something simple like that.  It is best to repair that with a brass hose connector and some SS clamps.  Other than that everybody else has mentioned all the problem areas: water pump, coolant tank, coolant tank cap.

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According to the dealer, it is the water pump, which I kind of suspected. Back in the late 80s I had a 944 and experienced 2 water pump failures with it. Just part of the whole ownership experience I guess. I still love the 996 and can't wait to get it back. Nothing I have driven has compared to the performance of the 996.

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