I started getting some weepage from the vent bolt too. I took the bolt off and it is a M12 x 1.5mm thread pitch. The part is mis-designed without a large enough sealing surface. Ideally the bolt should have a larger flange on it and then a sealing washer much like is used on an oil drain plug. I think the vent would seal better without the steel washer.
I better solution would be to replace the part with something that will work.
I haven't seen Jay's solution yet, but M2Race's solution seem like a very good one for someone who wants a turnkey solution, it has all of the bases covered, better sealing on the bolt, vapor collection, condensation and return and a filter to keep the dirt out. For the do it yourself type check out the following website to get an adapter from M12x1.5 to 1/8 npt. From there you can connect common hardware to make you own venting system. The simplest would be to connect a barb fitting to the 1/8" npt and then a hose connected to a filter. Note then any hose you use should be spec-ed to work at 250F+. I am trying to see if I can get a vapor collection and filter small enough to fit on the bolt fitting itself. It has to fit in a tight space and be light enough not to fracture the fittings from the engine vibrations. This won't work quite as well as the M2Race product, but may be good enough and more elegant in appearance.
http://www.xse.com/leres/ss/gaugepod.html
http://www.isspro.com/proddetail.php?prod=R7962
http://www.autobarn.net/eqoilpreselt.html
BlackICE
I better solution would be to replace the part with something that will work.
I haven't seen Jay's solution yet, but M2Race's solution seem like a very good one for someone who wants a turnkey solution, it has all of the bases covered, better sealing on the bolt, vapor collection, condensation and return and a filter to keep the dirt out. For the do it yourself type check out the following website to get an adapter from M12x1.5 to 1/8 npt. From there you can connect common hardware to make you own venting system. The simplest would be to connect a barb fitting to the 1/8" npt and then a hose connected to a filter. Note then any hose you use should be spec-ed to work at 250F+. I am trying to see if I can get a vapor collection and filter small enough to fit on the bolt fitting itself. It has to fit in a tight space and be light enough not to fracture the fittings from the engine vibrations. This won't work quite as well as the M2Race product, but may be good enough and more elegant in appearance.
http://www.xse.com/leres/ss/gaugepod.html
http://www.isspro.com/proddetail.php?prod=R7962
http://www.autobarn.net/eqoilpreselt.html
BlackICE