Midnight at the Oasis Yuma AZ

Glad to hear you're enjoying it!

I wonder if it's the booster or even the check valve.on the booster. You've seemingly already eliminated the master as being suspect. I would think of the master or air in the system but being intermittent, the booster makes sense. If you pump up the brakes with the engine off and hold pressure on the pedal, what happens when you start the engine?

05snopro440 said:

Glad to hear you're enjoying it!

I wonder if it's the booster or even the check valve.on the booster. You've seemingly already eliminated the master as being suspect. I would think of the master or air in the system but being intermittent, the booster makes sense. If you pump up the brakes with the engine off and hold pressure on the pedal, what happens when you start the engine?

Click to expand...

The pedal drops as you'd expect... I didn't think about the check valve - hmm - it seems odd that to me that this could even occur since there is the mechanical connection between the pedal rod to the booster, the intermediate slug between the booster and master, the booster just senses and adds pressure. It was a bugger changing the master since I had the bright idea to put it under the dash, so just changing out the check valve would be a lot more fun than replacing the booster..

The check valve is easy to check. Pull it out. On the vacuum hose side you should be able to suck air through but not blow. It should be smooth. I replaced the check valve on my 46 last year after I had a bad backfire. I was able to suck air through the old one after the backfire but it wasn't smooth air flow.