Mine did exactly this today.
Was driving to Tanunda to have lunch with my mother so I checked and topped up the radiator and expansion tank this morning. Got most of the way there (~60km I guess) when the temperature suddenly went from sitting at 3/8 to JESUS CHRIST BATTLESTATIONS AROOOOGAAAA
Pulled over, put the bonnet up, it was dribbling heaps out of the overflow hose while gurgling. Let it cool down for half an hour, refilled the core, then drove with the heater on full and the air-con on to get the second fan going back to Gawler (5km max), let it sit for an hour (ie went to the pub).
No sign of coolant puddle under the car but it took another litre and a half in the radiator after lunch, refilled the expansion tank to the full line again. Also noticed at this point that the top hose was sitting further back than it should so loosened the clamp, moved the hose and then made sure the clamp was sitting nicely. I also went across the road to a servo and filled a 20 litre container with water just in case.
I then drove back to Adelaide trying to use as few revs as possible, heater on full and aircon on, temperature guage didnt budge from 3/8 position. It gurgled when I got to my cousin's house (since I knew his mechanic mate would be there working on another friend's S14) and when I checked the expansion tank that was empty, but the radiator was completely full. I pulled the plugs, they looked like it had been running a bit lean but no sign of moisture.
Where in the **** is the water going?
Heater hoses are new, did them a couple of months ago. Thermostat is new.
I have a Cooling Pro radiator and new rad hoses ready to go in, but I dont know if the head might be a bit warped and letting it seep somewhere or not?
