Hissing noise?

[everitt1980]

Wondering if anyone can help me. Was working on the car yesterday fitting tip and a shortshifter and started the car to make sure that it was engaging all gears when i noticed a hissing noise coming from the engine bay. Seemed to be coming from under thr car so got under and could feel the air coming out of a join in a plastic round kind of fan located just behind the radiator at the bottom. Does anybody know what this is? Thanks. Just thought i would add that its not the actuall radiator fans its a seperate part.

 

[DPJ]

Secondary Air Pump?

 

[everitt1980]

I'm not sure mate. I guess its some kind of air pump with the air its pumping out but it must be malfuctioning somehow. Its about 8 inches accross and is plastic. Are they expensive?

 

[Phillc]

Do a search mate there is a repair guide some where.
Here you go http://uk-mkivs.net/forums/944474/ShowThread.aspx

 

[everitt1980]

Thanks alot pal just had look and printed this off. Gonna attempt this tommorrow.

 

[Avant4me]

Secondary Air pump

What exactly does this pump do?