i no im to late to anser this but sounds like air taped in heating pipe
1 unscrew bleeding valve should be near thermostat
2 unscrew colant bottle where water goes in
3 GET 3 3 empty bottles of cock ext cut bottoms of and place all 3 together .
4 put bottles in the water collent bottle .
5 get a hose pipe and pure in the bottles for aprox 20 to 30 mins to flush air flow out
sam
January 2010