David, you really need to get those heater pipes hot somehow - if you are sure that there is no air in the system, its likely that there is some sludge blocking things up somewhere. With the engine cool I think I'd be inclined to flush the complete system, including the heater matrix and pipes, with a garden hose and see what comes out.
John
December 2007
howtomendit.com for free repair help, information and advice.
