noisy toilet?

i put this question earlier but i don,t think i was explicit enough. I readjusted bath and sink taps, the water was switched off and the taps were disconnected and refitted. after the toilet has been flushed and just after the toilet system has filled with water there is a wailing noise which lasts for about 10/15 seconds. There is no tank just a combi boiler i assume i have an air lock how do i get rid of it please