Quote:
Originally Posted by Army
Holy crap!
7 seconds to bog down...
Hmmm I'll give it some thought.
As for the crankcase pressure effecting the vacuum pump.
Assuming you've got a piston pump => I can imagine that it would be harder for the pump to push against the crankcase pressure. If the non return valve in the vacuum pump was leaking then I can imagine that the piston assembly would be pushed back towards the engine so that the bearing race is always in contact with the bearing track on the front of the timing device. I think the crankcase pressure would reinforce the spring pressure in the piston vacuum pump.
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The shuttoff issue does not have to do with the Vacuum Pump.
It has to do with the fact that the Fuel Injection Pumps Camshaft and Governor Housing are connected to the Crankcase and exposed to the Crankcase Pressure.
One side of the Vacuum Shutoff Diaphragm is esposed to the Crankcase Pressure that is in the Fuel Injection Pump Governor Housing.
If the pressure inside of the Housing rises enough it pushes the Diaphragm the same direction Vacuum would pull it if you applied Vacuum to it and can shutdown the Engine.