Great suggestion, but it already has a new cap (.04) put on last week when I suspected and thought I fixed the problem.
Today, using a cell phone cam, I found the crack at the bottom of the tank near the firewall.
http://986forum.com/forums/uploads02...1492997916.jpg
I already have a tank on the shelf, so this week I'll do the dreaded job...
http://986forum.com/forums/diy-project-guides/50261-another-coolant-tank-replacement-diy.html
http://986forum.com/forums/diy-project-guides/56334-diy-coolant-tank-replacement-under-2-hours.html
Then hopefully back to the track for MayFast.
This time I'll try to focus on the line and keeping it smooth (see if I can keep the chief marshal from remembering me as 'that new Porsche guy who keeps spinning off the track').
http://986forum.com/forums/uploads02...1492998484.jpg
:cheers:

Nothing personal Jon, but that's one of the ugliest tank's I've seen. I'm surprised it didn't go bad a long time ago.
"That extra torque will get me into trouble quicker, but not necessarily around the track faster. I will get the engine swap done, but what I need for now is to make the basic car safe and reliable as I develop my skills." Does this mean you're putting the swap on hold? Don't you have other boxsters you can use for track time instead?

No offense taken. There was a lot of "ugliest" on this car when I bought it. The only thing that saved me from scrapping it was that much of what it needed was still available from my parts car and a few inexpensive parts from you.
I won't say that the swap is on hold. Just that I really needed to give the rest of the car some attention first. I have spent hours reading through NefMoto - Index and have many more to go before I really understand what I need to get the swap done properly. I have started collecting Audi ECUs and am learning the details of what goes on inside. Progress, slow progress. The next physical task will be getting the cradle fabricated. That is planned for May. 'This' is my back-up track car, but it's also my baby.
+++++++++++++
The coolant tank is out. Those DIY's I linked were great. I'm taking my wife out to lunch soon, so maybe I'll finish up this evening.
Notes:

• Disconnect the oil fill tube in the engine compartment first. Less stress on the hard plastic portion.
• One of the rubber hoses has a quick disconnect in the engine compartment. Easy to use that and get the clamp after it's all out.
• Use flexible hose clamp pliers.

The oily grit is probably left over from the blown and partially disconnected AOS when I bought the car. That's a hard to see/clean spot. The bottom 3 hoses came off pretty easily from here.
http://986forum.com/forums/uploads02...1493052600.jpg

The last hose could be pulled into the trunk far enough that it was easy to remove after everything else was freed.
http://986forum.com/forums/uploads02...1493052627.jpg

Here it all is, with the tools I used.
http://986forum.com/forums/uploads02...1493052642.jpg

Edit: All installed now. It was not bad at all. For the installation, I put all the hoses on the manifold, then pushed them through to the engine side. Easier to reach the hose to hose connections. I tried using a screw-type hose clamp. Bad idea. It is so much easier with the original clamps and hose clamp pliers. I wore 7 Mil nitrile gloves and didn't lose any skin or blood. Topped it off with Peak Long Life that I had picked up on the way home from the track. No need for the pink stuff in this car.

Update: Another short day at the track.
 

I kept busy on the car, but not the engine swap. After the coolant tank replacement I stripped a little more weight out of the car. The convertible top is out and its wearing a silver hard top. I have a scrapped (bad window) soft top that I am going to modify into a light weight sun-shade. I moved the window controls to the horse shoe and replaced the carpet with foam mats. New rear rotors (Meyle) and ceramic pads. Flushed the brakes, blue to gold. Got rid of the plastic bumper grill and riveted mesh in. I drove it hard on some back roads testing out the repair to the cooling system and it all looked good.
https://c1.staticflickr.com/5/4171/3...f56bc6e4_c.jpg

https://c1.staticflickr.com/5/4178/3...8d2c95aa_c.jpg

For MayFast, I thought of trailering it to the track, but figured the drive would be good as a final check and to finish breaking in the new pads. Almost a 2 hour drive and the temperature stayed on the '8', but after shutting down at the track I did notice the coolant had dropped about an inch below the min line. I topped it off, thinking it would be okay. During the first session I was flagged to the pits for fluid dripping from my car. I hoped that just topping it off and bleeding it again would get it fixed. Parked on a good hill, I ran about 20 minutes, then drove it around the access roads, high revs in low gear for a while. All seemed good.
(Rolling on my 'street' wheels and tires, not working on speed as much as basics.)
https://c1.staticflickr.com/5/4166/3...c25ff4f7_c.jpg
The next session I almost made the full 15 minutes. No flags, no spins, and the car was running well. ...Oh no, temp gauge going above the zero of 180. ...crap, it's still rising. ...blinking red light. ********************, end of track day. Momentarily the temp got to 250 as I pulled into parking. I nursed it back down running the fans and letting it run a few minutes at a time to circulate the coolant. I told my wife, "we are done with this 2.5. Next time this car comes to the track it will be the V8."
The car made the 2 hour drive home without trouble. Again the temp stayed right on the 8. At this point I don't know if there is a hot spot in the engine or just a little air trapped. I have ordered a vacuum/bleeder/tester for the cooling system. Maybe I'll find the problem, but my focus is going back to the swap rather than pampering this engine.
http://986forum.com/forums/uploads02...1494285686.jpg

My other big distraction is another Porsche that showed up at my house. "Pepper II". I didn't mean to buy it, How was I to know the seller would take 1/2 of the reserve price? Just needs a little dent pulled out and a cardan shaft bushing.http://986forum.com/forums/uploads02...1494286061.jpg :D

3D Modeling
 

Working on the engine swap a bit over the last couple weeks. I used the scrap rear half of my parts car to measure and fabricate a wooden model for the engine subframe. Today, I finally hauled it all to a local shop to have it fabricated. I have no idea how much it will cost :eek:, but this guy does really good work and has a backlog of customers.
No fancy 3D scanning computer modeling Like NERV:
http://986forum.com/forums/467843-post96.html

http://986forum.com/forums/uploads02/snip1496958167.jpg

I'm a bit more low tech, using a tape-measure, mallet, and scrap lumber:

https://c1.staticflickr.com/5/4281/3...23c7f9e1_c.jpg
https://c1.staticflickr.com/5/4261/3...04df92f8_c.jpg
https://c1.staticflickr.com/5/4240/3...9357444e_c.jpg
https://c1.staticflickr.com/5/4282/3...ea568c32_c.jpg

In about a week, it should be done. After that I will be eager to pull the 2.5L engine and fit the V8. The work only begins when the engine is mounted in the car. Months and months before I expect to drive it.