1963 no assisted brakes

[Greg1984]

Hello, I've got a 63 base model that I've had for 2 years.

I had an issue with it randomly stalling. Was diagnosed as a blown brake booster losing vacuum and causing it to stall.

Got the brake booster rebuilt, it solved the problem.

Now, I'm having an issue where randomly some days I'll lose all brake assist. Morning its fine and afternoon I have zero assisted brakes.

I cant see any vacuum leak. With the booster being rebuilt, I'm at a loss what might cause this. Any ideas?

This page contains affiliate links for which I may be compensated. As an eBay Partner, and Amazon Associate I may be compensated if you make a purchase at no cost to you.

 

[red65]

Have any brakes? Sure vacuum line running to correct source?

 

[Kultulz]

The Booster​

No matter if the booster gets vacuum from the engine or a pump, if it is damaged, the brake pedal performance will change. The condition of the diaphragm inside the booster is also important. If it’s cracked, ruptured or leaking, it won’t hold vacuum and can’t provide much power assist. Leaks in the master cylinder can allow brake fluid to be siphoned into the booster, accelerating the demise of the diaphragm.

If there’s brake fluid inside the vacuum hose, it’s a good indication that the master cylinder is leaking and needs to be rebuilt or replaced. Wetness around the back of the master cylinder would be another clue for this kind of problem.

To check the vacuum booster, pump the brake pedal with the engine off until you’ve bled off all the vacuum from the unit. Then hold the pedal down and start the engine. You should feel the pedal depress slightly as the engine vacuum enters the booster and pulls on the diaphragm. No change? Then check the vacuum hose connection and engine vacuum. If it’s OK, the problem is in the booster, which needs to be replaced.

SOURCE - https://www.brakeandfrontend.com/vacuum-brake-booster-diagnostics/