Overheated today 2002 r53
Driving home today, no traffic about 20c outside I pulled up at a shop put into neutral and the temp gauge suddenly shot up to red and started flashing, I switched engine off and waited about 3 minutes while the fan was on cooling the engine down.
Started her up again with the intention of getting home which was about 4 miles away, got about a mile when the gauge starts behaving erratically, hitting the red and falling back down periodically. I put the air con on and the temp steadied for another mile until it started flashing red again and I pulled over immediately. Opened the bonnet and checked coolant and the tank was empty and looked like it had been dry for some time. Topped it up with a litre and drove home, temp gauge was erratically swinging between normal and red.
Topped up with more coolant at home, took it for a spin and temp was fine, rechecked coolant later and topped up,accordingly. Drove it again and idled for 10 mins no problems.
Any ideas what caused this? Was it really just lack of coolant, the system sucking in air?