Proper Air Ven Installation

Mike Right

My home has a one pipe steam system. Two floors have steam radiators (main floor above the basement and the top floor). I recnently replaced all the air valves just to assure they were all in proper working condition. I still get a noisey / gurgling sound from only one spot in the house. This is a top floor radiator or the pipe leading to it. When I read some of the tips on this site, one of the things mensioned that could cause this was an improperly installed or improperly functioning air vent. It went on to say to check to see if the air vent is installed on a extension pipe. This one noisey radiator is the only radiator in the house that does have the air vent conected to an extension pipe, which connects it to the radiator. Coinsedence? I wonder if this could be the cause... Any ideas?? The tips on this site said to check to see if this was the case, but it said nothing more about it (IE is this always bad, what to do to correct it, etc) I believe it was connected in this way because without the extension pipe there is a part of the radiator itself that extends out a bit and would prevent you from screwing the air valve on with no extension. Any ideas / input is appreciated! Thanks in advance!