Hi all The bother I`m getting is pressure pulling down my oil filler cap and the same with the dipstick when I gently pull it up. After having a search it looks like my problem could be the crankcase breather valve I took of the UFO shaped valve and you blow through it both ways so that must be goosed. Anyway my question is how many check valves do I need to replace obviously this one and having a nosey round on the net I see there is also a small green valve under the inlet manifold area, does the bex engine have this one as well? As GSF only list the ufo one for my car. Also is it worth cleaning/replacing anything else? many thnaks for any info..