75 1603 brake & vacuum problems

K

Kitist

New member
I rescued a converted former school bus and the brakes are driving me nuts. Sometimes applying the brakes is like standing on a brick with very little "slow down" effect. Much too scary for me! Other times the brakes seem to be "normal". Recently, it developed a vacuum leak that I can't locate. It has always had a vacuum problem, normally running about 20", but now it is down to 10" and I get the dreaded "vacuum" light. (it's a real thrill going downhill at night!) does anyone have any thoughts about what I might do?
 
Welcome to the forum. Assuming this has vacuum assist brakes, examine the vacuum line from between the manifold and the booster for leaks. Replace the line if any cracks or dry rot is observed. Finding none, disconnect the line from the booster end and plug it. Fire the engine and observe manifold vacuum at idle. If the normal, steady level is restored, then you now know that your vacuum leak is within the booster unit which will need to either be sent off for a rebuild or replaced as the internal diaphragm is perforated.
 
Yup, vacuum assist. dual Vacuum assist cylinders with a reservoir mounted between them. I hadn't thought of the simple idea of checking the location of the leak by eliminating the vacuum circuit. Thanks for the suggestion.
Now I just have to get it far enough off the ground so I can safely work under it.
 
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