I have a vauxhall astra 1.6 life. My car recently started whistling and i tool it to the mechanics. Now my mechanic says that he couldnt take the oil cap off because there was too much pressure in the engine. Now when he eventually can take off the cap the car runs fine, even when he takes off another air pipe again and replaces the oil cap again the car runs fine. But when everything is back in its place air pressure seems to build up inside and it starts whistling (like a old style kettle boiling).
Any help or advice on this matter would be hugely appreciated.
Right sorry guys seems i got the wrong information!! Ok its not that there is air wanting to get out but infact the other way round. IF you was to put your hand flat on top of where the oil is poured into the engine, it will suck it in. If you was to do this where the dipstick is same problem. Although if you leave the cap or the dipstick off then the engine runs fine.
I think i might repost as i think this may change peoples ideas.