Jon986

Ok, thank you for the insight. I do have the updated cap because a couple years ago it was leaking out of the top of the old one. This one seems solid. I did fill the reservoir with distilled water today and a little bit dripped out of that hose (if there is a reservoir overflow hose, that's a safe bet for what that hose is I guess) but it seemed to be staying level after that. I attached a couple photos of the reservoir tank. In these photos, it is empty, even though that faded mark makes it look like there is coolant in there. I also attached a different photo showing that open hose (that may be the overflow hose) Would possible culprits be: Water pump failure? It didn't seem to be a source of any issues when I was under the car, but I've read how failed water pumps cause coolant dumps Thermostat not working? If my neighbor noticed my fan working too hard the other day, it seems like the system was working hard even before it leaked all the coolant. I had it towed to a shop today so they will pressure test the system and I should know more soon. From what I've read, it sounds like whatever the issue is, I should take this opportunity to replace the coolant reservoir, the water pump, and the thermostat. Anything else I should do that is a common maintenance issue while they are in there? I'm not sure how old the belt is...I've only had the car about 20k miles. Thank you Jon

2002 Boxster S (130,000 miles) - Brief history: ~500 miles ago: changed the oil and filter myself about 500 miles ago (Mobil 1, 0w-40). Didn't notice any leaks. ~100 miles ago: had a shop replace the rear toe arms with adjustable ones since the toe was way off on the right rear and couldn't get dialed in with the stock toe arms. 2 days ago: neighbor asks if my car was running hot because the fan was running loud when I parked at home after driving for an hour. Yesterday: drive 10 miles and when I park, I get out, walk about 5 steps, then coolant starts gushing out of the center between the rear wheels, and steam coming out of rear passenger side vent. Coolant tank is empty, but no leaks in the trunk (checked under the carpet liner and foam panels). Have it towed back to my house. Now I'm trying to diagnose what went wrong. I took off the underbody liner to get a better look at the water pump, etc. It looks like there is oil and coolant sprayed in multiple places. Coolant drain plug is tight and dry. Oil level at dipstick is fine. Water pump doesn't feel loose from what little I can tell with the serpentine belt on. I poured about a pint of distilled water into the coolant tank in the trunk (which is yellowed and should probably be replaced whenever I find what is wrong) and noticed water dripping from the open end of a hose (see attached photo). I'm not sure what this hose goes to or if it's supposed to be open. Any thoughts on what to try or look at next? Any help is MUCH appreciated! I have more photos I can upload if that's helpful.