The vacuum assist brakes have been progressively getting worse. It's so bad now that I'm getting virtually no assist. I attached a vacuum gauge to the vacuum pump and it it produces 8 inHg at idle and 12 inHg with throttle. As soon as I turn off the engine, vacuum drops to zero. When I blow into the vacuum pump, I can hear air leaking. Is this not normal?

What's my best option here? The second option is much less expensive because I already have all the parts except the electric vacuum pump which is relatively inexpensive.

Option 1
Convert to 2nd Gen Vane style vacuum/power steering pump?

Option 2
Buy electric vacuum pump from 03-04 Dodge cummins
Convert brakes to hydroboost

 

Unless you have a vane pump kicking around, or cheaply available, I'd go the hydroboost route.

I used to have a '95 f350 that I did a hydroboost swap on.... locking up 35's on a PSD crewcab was pretty sweet.

Edit: Another elec vac pump route is the 99+ superduty diesel. Haven't checked... might be cheaper?

 

Any difference between a vacuum pump from a 12 valve and a 24 valve Cummins engine?

 

Dunno for sure. I have a hunch the accessory drive port on the timing case and gear pitch stays the same between 12v & 24v engines. Not sure about common rail though.

 

I have the rotary vane pump on my 12 valve that's in my burb with vacume booster and it works great...