oldbeek Posted August 5, 2014 Share Posted August 5, 2014 The vacuum pump is so hard to RxR I feel a need to inform all of a glitch I found in the Cummins Forum pictorial and instructions. The seal directions and picture of the seal coming out are WRONG! They show and explain that the dust seal side of the seal faces the vac pump. The cummins instructions say that the spring side of the seal should face the vac pump. The spring side of the seal always faces the area to be sealed. Link to comment Share on other sites More sharing options...
rancherman Posted August 5, 2014 Share Posted August 5, 2014 (edited) hmmmm, in a vac pump... not so sure about this! the lip seal is pointed so the pressure differences within a pump, either vacuum or pressure, cause the lips to 'bite down' when there is a pressure difference... making for a better seal. so in a vac pump.. wouldn't the lip seal be pointed so outside atmosphere (high pressure) would be helping the seal do it's job? you are right, when it comes to keeping oil in, or water in... lips face the material to be kept 'in'... but on a pressure situation, atmosphere will be higher and always seeks low pressure... blowing through seal lips pointed backwards would be easier. Edited August 5, 2014 by rancherman Link to comment Share on other sites More sharing options...
Wild and Free Posted August 5, 2014 Share Posted August 5, 2014 Key word is "Dust" seal, there are many applications where lip seals are used as a dust seal and the spring side faces to the outside of a compartment versus in as would be the normal case if it was to be used as an oil seal. It has been many years since I have done a vacuum pump reseal so without seeing pics of it I can't say what is right or wrong in the pics. In fact there are many cases where lip seals are installed lip side out of compartments that get greased so the grease can ooze past the seal lip and the seal keeps moisture and dust out but while being greased prevents them from being pushed out as the seal won't hold pressure and will allow the grease to purge past the lip. Link to comment Share on other sites More sharing options...
oldbeek Posted August 6, 2014 Author Share Posted August 6, 2014 The cummins bulletin that comes with the seal page 3 fig 7 says to put the dust lip side away from the vac pump. Good point about the vacuum. So why does the oil want to blow out of the vac pump? Link to comment Share on other sites More sharing options...
mopartechnician Posted August 6, 2014 Share Posted August 6, 2014 Vacuum pump is lubed by oil Link to comment Share on other sites More sharing options...
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