Sounds like a small air leak and when I press the brake pedel in about a half inch, it stops. Could this be due to the vacuum pump going out? Is the vacuum system tied in with the transmission at all? Basically, how does the vacuum system work and what are the components on it?

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Also, what is the technical term for the coffee can associated with the vacuum system? From what I have read, that can may have a small hole in it or the vacuum pump diaphram may be rotten. Are all of these things on this early model 7.3?

 

Sounds like your brake booster may be leaking, the coffee can is a vacum canister

 

Found out a while ago that it is the brake booster. Would this leak cause the tranny to act up and the front hubs to not lock in?

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Being that it is part of the vacuum system.

 

front hubs no, trans maybe.

 

DC, what all components are tied into the vacuum system and the effects that it has on them?

 

matters on the truck. vac system components are vac pump, vac manifold(on firewall normally) brake booster, low vac alarm, and some trucks the heater doors are vacume operated. i dont have any experiance with the e40d trans, soo not sure if that uses vacumm at all or not. i know the c6 did on the modulator.

 

I'm pretty sure the E4OD doesn't use vacumn input. It will get it's info from the tach sensor and possibly the rear speed sensor.

 

Not sure but, the tranny did start acting right once I replaced the booster. Still haven't had an extra pair of hands to help me bleed the brake lines.

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Worst part was pulling the brake fluid bowl off of the old mastercylinder.