I have a 2004 E350 6.0. We have braking problems that I think might be vacuum related. The pedal is very hard to press and the truck slows to a stop but you have to really stomp on the brake to stop. I checked the pads and they look like new (almost), I then thought I have a master problem so I replaced that but the same hard pedal problem. How can I troubleshoot the vacuum pump? Mine is engine mounted and driven by the belt. What vacuum should I expect to see?


Thanks for any suggestions or help.

 

Are E-series 6.0 brakes powered by vacuum? On F-series, it's done by power steering pressure, called a hydroboost system.

 

Yes the E series is definitely vacuum assist. There is a can behind the master with a vacuum hose and check valve attached. The main vacuum hose comes up from the pump deep down in the bowels of the engine and is distributed through a manifold attached to the cowl. I can feel vacuum at the manifold but don't know what the reading should be.