Brake bleeding

[sdc eastern ia.]

I have a 72? IHC 1700 345 and am having mega trouble trying to bleed the brakes. There is a micro-loc system on it and I wonder if this may be the problem. They will pump up then bleed until I see no bubbles, but the master cylinder will not hold its prime. Peddle goes to the floor easy. Anyone have a better way?

 

[ericlb]

i had a similer problem with my bucket truck, if you have a actual mico-loc brake hold devise, there is a bleed fitting on the unit itself and mine was trapping air, now did you replace the m/c? there may be a problem with the new one bypassing, did it bench bleed ok? [hard and hold pressure] depending on how the truck is now you may have to use one of those pressure bleeders to get the air competly out of the system,you did start at the wheels fartherest from the m/c right? did you bleed the hydrovac unit? those can be a source of problems too

 

[sdc eastern ia]

Master cyl. bled fine All other corners were ok but I think you hit it with the micro- loc. Will try again or maybe just remove the loc.