It is not normal for the bleeder value to open by itself. You may have a stuck thermostat or a radiator blockage. To answer your other question - No, the OEM coolant tank isn't very fragile. I swapped mine out after 18 years and it wasn't leaking. I did it proactively because it is made of plastic and was very yellow. On the other hand, I have heard about problems with aftermarket tanks.

Allowing the car to idle for extended periods is highly frowned upon.

 

It is normal for the shaft to rise when the system is pressurized, engine hot. It is not normal for it to stay up when cold unless the bail is snapped upright.

The bail is not a pressure release device. It is a vacuum release device. The pressure seals the valve as you have seen.
If you flip the bail up it holds the valve open so that air pressure is equalized as the engine cools down (overnight is best). This allows trapped air to migrate to the tank, probably works best if you can park the rear higher than the front.
The best way to bleed these systems is to use a vacuum device. UView55000 or equivalent.

https://www.ebay.com/p/Uview-550000/...9638077&chn=ps

 

Adding another factoid: Since I've put 3 gals of distilled water (and no antifreeze) in the cooling system to refill it when it lost coolant, I've now got a highly diluted solution in there. It still is pinkish, but not as deeply colored as when I picked it up in Feb.
I'm now topping up the expansion tank only with straight G-12 (Pentafrost Pink) to try to bring the glycol concentration back up. So far, I've added back in roughly 2+ liters of Pentafrost. Maybe running straight water which boils as 212 degrees at atmospheric pressure is the wrong thing. Antifreeze does two things: it lowers the freezing point, and it raises the boiling point. Since it noticed the sound of liquid percolating in the engine when I've parked after a long run, maybe the diluted coolant was just boiling in the engine?
One additional comment: I tried running the car without the AC on, and found that both electric fans do kick on when the needle hits the right edge of the zero on '180' degrees. That is a good sign that the fan sensors and circuits are working. In addition, revving the engine to over 2000 rpm walks that temp reading back down to the middle of the '8'.
Since the non-Porsche coolant tank cap may have been the initial cause of coolant loss, and replacing it with a proper blue Porsche-numbered one, it now may allow the system to work as designed by getting the coolant mix back to 50/50.
Still planning to replace pump, thermostat, and drive belt, just to re-establish a normal maintenance schedule.
As for the expansion tank itself, it may not be leaking after all, since it remains highly pressurized for days sitting idle. That original coolant loss might have been due to the old cap, which would explain why the vaporized coolant was not obviously visible. I was adding to the mystery by diluting the coolant and causing boiling and an over-pressurized tank. I also have to learn better how to get all that trapped air out of the system ... :-) !

 

 

Yes, I was hoping the new Porsche-brand cap would maintain pressure and also not blow out the next weakest link in the coolling chain. So far, all I now get is continued coolant loss through the new cap. Car doesn't seem to overheat, but the left rear of the car always smells of antifreeze plus hot rubber, and I still have to top it up frequently. Both front fans kick on when they are supposed to. The only new factoid I can report is regarding the appearance of the coolant. When I perform the Porsche-recommended burping of the system at 4000-5000 rpms, I notice the coolant appears opaque. I'm now concerned that my radiators, heater core and the engine itself have that dreaded precipitated sludge brought on by mixing antifreeze types. Does a thorough flushing of everything eliminate the overheating, I wonder? I will know more once I actually do the thermostat/water pump/drive belt project.

I got sidelined this week diagnosing an electrical problem, but I am happy to report I solved that one fairly easily. The brake lights stopped working. I've also never been able to get the cruse control to work. After a little digging on line and in the tech manual I isolated the cause to the brake light switch. It also happens to communicate with the cruise control system. Once I got the switch out (not too difficult if you can contort your body a bit), I took the switch itself apart and found a worn contact. Once rebuilt, reassembled and installed, I got the brake lights back and surprise, surprise ... the cruise control works!

Now back to the boiling water at more than 212 degrees project .....

 

I've never seen my coolant looking opaque, so you may be on to something.

 

I watched a video on how to remove and replace the radiators. The camera showed what happened as they were each removed ... a viscous glop oozed out of the pipes. Now, if there is some of this precipitate in my 911 cooling system, and it is the original thermostat stuck in a partially opened posution, and some of the water pump vanes are broken off ... I may have found root cause! Just not enough coolant moving around to avoid boiling and clean-out. We'll see.

 

After another frustrating review of the Porsche dealer's PPI from last February, I vented with the dealer principal who said to bring the car in. After looking at it for an hour, their tech concluded that it was the topside of the coolant expansion tank that had cracks. The hot coolant was not escaping around the new Porsche-brand cap. Even though the system would hold pressure overnight, when the engine was at operating temp and pressure, it would leak vapor through tjese micro cracks. Why they couldn't detect this back in Feb is beyond me however. Unfortunately, I've spent at least 125 dollars on G-12 antifreeze and 30 for the cap since then.

Word to the wise ... even though your tank looks new and whitish, it could still be cracked.

 

I posted this reply on the other thread dealing with normal operating conditions, so apologize for the repeat. Just wanted to share my learnings.

Finally tackled the cracked tank on my 01 Carrera Cab. 3 hours to get tank out; 1 hour to slide new one back in; 2 more to button it up.

Key Learnings:
* Using a 1' long brass tube attached to some clear 1/4" hose worked very well to syphon the tank completely dry.
* You absolutely need to drop the engine 1.5-2" to get the tank in and out.
* Removing the coolant level sensor from the tank before pulling the old tank out turned out to be much easier than I had thought. Just wiggled it a bit to figure out how to unlock it without breaking it.
* The fuel rail on the left side is in the way! Even dropping the engine was only 95% enough, so figure you'll need a 17mm wrench to pull off the line's compression fitting that is in the way.
* Recommend needle nose locking vise grips to deal with the Porsche hose clamps, if you don't have proper pliers.
* Also used cord to tie back disconnected hoses to give more room.

Now my fingers are crossed this is the needed fix.

 

I also recently tackled this problem along with the help of a highly trained Porsche tech. He had all the right tools. But even still, it took quite a bit of time to accomplish. One reason is the car had to be completely flush because the PO put the wrong type of coolant in the car. The tech dropped the engine as far as it would go and disconnected all hoses including the fuel lines as well as removed the coolant level sensor. We drained the coolant first out of the tank and engine. Then proceeded to replace the expansion tank. Even with the engine dropped, that tank was still painful to get out. After the tank was in, we then flushed the entire car. Hardest part is getting the coolant out of the radiators and heater core. Once it was cleansed, we used an Airlift system to put the *right* coolant back into the car. Glad it's fixed now. I'm tired of seeing puddles of green coolant in my garage.

Thanks for sharing!

 

green coolant?
Hmmm ... I've been using G-12 pink coolant, as specified back in 2001. Maybe I'll switch to G-40 the current Porsche dictate when I have to flush in maybe 12 mos. But geen ... not sure that's what is recommended for aluminium blocks.

 

Hot pink is the correct coolant, B3 was indicating that he had the wrong (green) coolant in the car before the flush. G-12/13 are fine.

 

 

Sadly I am now having my engine replaced. My coolant loss was apparently through the head gasket, and probably was occuring long before I bought the car. The combustion chamber gases were blowing past the head gasket and not only contaminating the coolant but also over-pressurizing the coolant tank and superheating the coolant. At 3 years of age, this car was already showing systemic cooling problems. It has had at least 3 water pumps and three coolant tanks. Nice that the selling dealer and the local Porsche dealer (who did a farcical PPI!) had the service history available but chose not to disclose. Walk away fast from any car you test drive where you smell coolant! And gasoline in the coolant tank!

 

Are you sure it's a head gasket? That is extremely rare as the gasket material is stronger than the engine itself. It's more like likely that you have a cracked cylinder head, which is fixable. If it's the 1-3 head, you may be in luck as someone on Rennlist has a new one for sale at a very good price. I'm guessing that a head from 2000 would fit a 2001 but you would have to verify. If not, there are well respected shops that can repair a cracked head. I would confirm the diagnosis before moving ahead. In any case, the first thing you want to do is thoroughly flush the cooling system with detergent. Oil and/or fuel will deteriorate all of the rubber hoses and that would be very costly to replace.