try bleeding the coolant system again as you have had pipes off the water runs out and the system fills with air it may just need bleeding just like radiators do in a house when replaced hint hint,,,, one way to bleed the the coolant system is by a bleed valve on the one of the heater matrix pipes or simply just pull the pipe off coming out of the matrix, top up the coolant and when the waters through simply replace or tighten
garthy, November 2007