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On 2 May 2004 at 20:43, phil cain wrote: > On the Fuel injected ones(68-70) the vent went from the oil breather > stand to the air filter, the aux air vents to the air filter also. On > the later T-3(71-73) they also vented the valve covers and or the > heads to the air filter. some of the models was connected between the > bottom(dipstick filler Pipe) and to the oil breather stand then to the > air filter, many different years, all to have a negative pressure on > the engine. '71 is the early style. Only 72-3 got the later style. The late ones got a hose from the breather which ran only to the intake manifold via a small limiting aperture. The intake manifold certainly has significant vacuum, but the aperture limited the amount of flow that could get thru. > All the earlier engines had a setup for keeping negative pressure on > the engine, they all went to the air filter. Just like the > T-1's(60-68)vented to the air filter with a mast hanging down in the > slip stream with a negative rake(Rubber tip with a slit in it facing > aft) on it for help with the vacuum at speed..I haven't explained it > very well but it's true.. The early versions had a hose from the breather to the inlet side of the air cleaner. There would be a VERY slight vacuum there, but it's only the amount due to the pressure drop between the outside world and the inlet of the air cleaner. You're correct that it's less than atmospheric, but I don't think it's significant. The rubber tip on the draft tube is a valve to let condensed water out. It faces down. It is designed to have no effect on the pressure, but the slight air cleaner vacuum would still be there. -- ******************************* Jim Adney, jadney@vwtype3.org Madison, Wisconsin, USA ******************************* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org