Driving up the M5 on Sunday, low coolant warning light came on. Checked the temperature gauge, no significant movement, so carried on. A few more miles, and I notice "smoke" coming from the back of the car, pulled off at the next junction, opened the bonet lots of steam, though the car gad not overheated or even close to overheating. I could hear a hissing sound somewhere from the rear of the engine bay and located the leak. It was the steel pipe that runs across the bulkhead at the rear on the engine bay had split, jeeze more rust Called the RAC who carried out a bypass, but could not include the heater and it was a cold day. New parts now ordered still running with bypass hose bl**dy cold in the car though, reminded me of my first Mini with no heater