coolant temp, starting turnover strange behaviour - ideas?

Hi, Just drove the 996 900 miles on a holiday road trip. At speed on the highway, ran like a champ and actually I was very surprised - what was a tired, soft and flabby suspension on surface streets and up to 60mph really tightened up at speed. I experienced this before when I took her to Fontana / AAA ROVAL - she was surprisingly smooth and capable up 7/10 and in the triple digits, much more so (and MUCH more confidence inspiring) than I expected given suspension behaviour on the road. I wonder if operating in the range it was intended "loosened things up" in a good way? Aero pushing down the front so the steering tightened up significantly? This of course doesn't make any rational sense as I know the basic design has a reputation for front end lift and feeling too light ... Anyhoo... 1999 996 C2 just turned over 83000 miles stock 17inche rims IMS and RMS done, recently had AOS, spark plugs and tube, seals, done. as well as +2qt LNE deep sump and oil pan. VERY recently had coolant pump and bottle done. original suspension (just received ROW030 kit but now, see opening remarks, debating whether I should install it or just keep it in the box and enjoy the suspension rejuvenated with my recent "German suspension tune up" for awhile...) two weird experiences that had me worried - making a u turn I stalled the car (yeah, yeah, I'm "that guy" - the PO installed a very very strange finicky carbon clutch that is either on or off, and doesn't grab at all until the very top end of the clutch travel. Terrible street clutch...) and when I tried to restart (yes, I know how to start the car) the started would engage electrically but then nothing - no attempt to crank, just all the lights dimming, then all electicals going out, until I let off the key, then electrical system goes back to normal (ignition key position one) This happened 3 times; attempts 2 and 3 I made sure all electrical system drains were shut off including HVAC and any lights that could be switched off, sound system (I don;t listen to radio anyway, I love listening to the drive train and chassis / suspension do their work) etc I waited 15 seconds (sitting in the middle of the street! YIKES!) with the ignition completely off (keys removed, then replaced, unturned) and then it started, albeitly hesitantly. One crank, slight slight pause, then ignition. No other issues since (400 miles and 30 hours later) The battery is slightly underpowered for the spec (3 year old battery on a 5 year spec life from PO, CCA slightly less than factory rated spec) but all mechanics Ive asked told me as long as it turns over reliably, dont worry about it. Thoughts? The other issue was coolant temp - before water pump and can were changed, urban operating coolant temp gauge usually showed c. 190 - needle always between right side of 8 and middle of 0, only edging right side of 0 on very warm days in start and stop traffic. water pump and can (T-stat too) were changed becauae we detected a slight coolant leak and well, it was about time...I inspected old pump, all blades in good condition and whole. After change, operating coolant temps seems to have dropped by a few degrees, everything else being equal. Two days ago, when the lead car got lost and we ended up in stop and go traffic for 20 minutes, the coolant temp started to creep up - from center of 8 (180) to center of 0, then pegged at right side of 0, sometimes just past 0 to show whole digit. Ambient temp was 65F, cooler than normal op temps for me and this car. I was worried it would keep going up; thank goodness it didn't. But it did (not so slowly) and consistently creep up from mid-8 to right 0 (about 190 to c. 205) - enough to worry me. This is higher than I;ve ever seen it, even after 3-4 laps at AAA Fontana at 7/10 and consistently shifting at 6800rpm or sitting in LA traffic for 30 minutes at a time and higher ambient temps. Above was 400 miles from home so I was doubly worried. Got on a short stretch of freeway and it didnt' come back down. Went in for lunch, an hour later got on the freeway and headed home. Coolant temp was a steady c 185 (middle of 8) all the way for 400 miles. Thoughts? stuck valve that got unstuck? flakey new thermostat? Other? I have to admit, thoughts of hot spots and all sorts of other nasty 996 infamous nightmares danced through my head (thanks, internet!) but I kept the faith, and so far (got back late last night) so good. And yep, that "German suspension tune up" held up! Wonder if this is a new (for me) phenomenon akin to the famous Italian tune up? (run the engine at "performance" operating temps for 15-30 minutes, clears up a wide range of engine "hiccups" - it did wonders for E39 M5 and myriad Italian exotics) Thanks in advance for any thoughts or suggestions.

Sounds to me like you need to have the battery tested. As for the cooling scenario, it's hard to say given how essentially useless the gauge is. Read the "things you didn't know about your 996" thread to see how to monitor the actual coolant temp using the HVAC readout.

The battery issue you mention could be a weak battery (the most likely culprit) or it could be some kind of electrical ground problem. Grounding problems can also cause gauges and other things to malfunction. Maybe others can weigh in on the grounding system locations on the car.

it's probably 2/3 way through life cycle anyway and being less capacity than spec it is irritating to hear the starter motor struggle for a split second before turning over.

Lot going on. The starting behavior could be due to a battery issue. That the battery is not even up to what Porsche specifies is troubling. In some cases Porsche has even upped the specification so even the "stock" OE battery is not up to snuff. You might have managed to squeak by living in an area where temps are mild. Up to you but you might consider replacing the battery with one that is properly sized, that is has the recommended CCA'a and AH's and is otherwise physically compatible with the car, the battery box, the leads, the vent hose, etc. If you replace the battery use this as an opportunity to ensure the battery connections are good not only at the battery but at the other ends as well. There have been reports of battery issues or issues that mimic battery issues from marginal battery lead connections not at the battery but at the other ends. If the symptoms return there is the possibility the ignition switch is wearing out. Another possibility is the alternator is not producing enough power to replenish the battery and supply power needed by the rest of the car. But a bad alternator is rather rare. The coolant gage action you noticed suggests to me a fan is not working. You can without much work tell if a fan is working or not, by getting the engine up to temperature by driving around -- A/C off! -- and then at home in the driveway raising RPMs to say 1500 and holding this level until you or a helper detects the radiator fans come on. It helps if you can monitor actual coolant temperature either by an OBD2 scan tool/data logger or by in some older 996's via some diagnostics menu accessible by the A/C control buttons. At what temperature the fans should come on at least low speed varies some from model to model and from MY to MY but my Boxster's fans come on low at 212F and switch to high speed at 216F. The fans shut off when the coolant temperature drops to 205F. Oh, be sure the A/C is off as if it is on this turns on the fans. To test the fans at least come on low speed is not hard. To test when they switch to high speed is harder to do under a shade tree, so to speak, so you might consider having the car's radiator fan stages checked out at a shop that has a diagnostics computer than can do this. However, even this is not 100% reliable. I had a non-functioning driver's side fan on my Turbo and there were no fan stage errors but of course the fan was not working and I had it replaced.