What does the vacuum line that I have outlined in yellow do? I tried to change it out to a Samco vacuum line but, it appears to have a check valve in the line at the red X. (That is probably why it has an arrow and "eng" written on the hose. )

Anyone change this line out and remove/replace the check valve?

Maybe I will just buy an extra from Lokey next time and try to take it apart and replace the check-valve into the Samco line.

 

I think it supplies pressure / vacume to your brake master cylinder.......