Bleeding New Year

 Happy New Year!

After buying our bus in April '20, we replaced the rear shoes and cylinders and bled the system. Front pads seemed fine, as did hoses. We have driven the bus many miles since then with the brakes working well. My daughter took the bus to visit a neighborhood friend and reported that the brakes faded almost all the way to the floor. She was able to pump the brakes to stop. However, after the pumping the brakes were fine again.

On her return, I took the bus for a test on the exact route, no issues and the brakes were fine there and back. I also tested the booster by pressing the pedal while starting and, as expected, the pedal dropped slightly - but settled well over half the available travel, as its always been. Fluid is full with no apparent leaks.

The reason why seemingly good brakes would intermittently fade? Brake master cylinder - apparently, when a MC is about to fail fully, intermittent loss of pedal pressure is common.

I soaked the brake pipe nuts in PB Blaster for the night in prep for the new cylinder.

On a side note, we used newly purchased Harbor Freight 6" ramps, should have bought them years ago. Drive right on, rock solid, and lots of work room. Great deal for $45 and rated for 13000 lbs.

We got the old MC off and everything came off fairly easily. The only possible issue was on removing the filler tube. There appeared to be a "shouldered, black rubber, inner insert at the inlet and the shoulder area is torn up or deteriorated. We ordered a new one.

This is the MC we used. The switch positions were the same as the one we took off. Even came with new bottle mount seals and rubber O-ring. AND it came with a bench bleed kit. Pretty good for $50.

After install, on brake bleeding day and the brakes came back fully. We did not have to "bench bleed" the master cylinder, but took out a lot of air when bleeding. Thankfully the bleed screws came undone easily after soaking all night in PB Blaster. On a test drive, the bus stopped true and straight, no heat generated on the wheels from sticking brakes, etc. We're now back in business.