Hi Everyone,
I've run into an issue bleeding my brakes and thought I'd reach out to you all for help.
The background: The truck is a 1953 3100. I've spent the last couple of months replacing the brake system components with new versions of the originals (new master cylinder, hard and soft brake lines, wheel cylinders, shoes, springs and retainers). The only parts from the original system that are reused are the brass blocks and the banjo bolts, although I did replace all of the copper washers around the blocks.
Everything is installed and the system was filled with DOT 3 brake fluid. I started the bleed process using the fill and pump method, but forgot to add more fluid and pumped the master cylinder dry.... Then I lost my helper, so I bought a mightyvac. I did have some vacuum issues with the mightyvac, similar to others who have already posted about that, but it did draw some vacuum and some fluid to each wheel cylinder. Not knowing exactly what the fluid would look like when the system was completely purged of air, I filled the reservoir after doing each wheel and tried out the brake pedal. The first pump was rock hard. Then each successive pump got softer and softer until the pedal could be pushed to the floor. I looked for leaks and found some minor ones, which I corrected. Refilled the reservoir and had the same thing happen as the first time. Hard to push at first, then softer and softer. However, no more leaks.
So I assumed that I still had air in the lines and decided to redo the bleeding with the mightyvac. To deal with the vacuum issues, I took teflon tape and wrapped the upper half of the bleed valve. That seemed to cure most of the vacuum issue, although I think that I might be drawing some air around where the tube goes into the rubber fitting that attaches to the bleed valve, but it does draw a solid vacuum (25 lbs).
Now the problem: I am getting tons of air bubbles through the hose on the mightyvac. More than I expected. This time, though, the bubbles are really big, instead of the really small ones which were associated with the vacuum leak.
I've made really sure to maintain fluid in the master cylinder after the first mishap. Now I'm wondering if the mightyvac is finally drawing our the air from the lines or if there could still be a vacuum leak somewhere.
Questions:
1. How will I know when the line is completely purged of air? Assuming the mightyvac is working properly, will the fluid that comes out fill the tube and be free of bubbles?
2. Many people mention "pumping up" the system. I thought that if the system was completely purged of air, that the pedal would be very hard to push once the system was completely filled and the cap installed. What does pumping up the system mean?
3. I couldn't find anything in the shop manual about exactly how full to fill the reservoir. Is there a correct level? If so what is it?
4. During the removal of the master cylinder cap, I accidentally broke the gasket. I am still fitting the gasket around the cap when I install it, but am now wondering if the gap in the gasket could be letting air into the system. Is the gasket around the fill cap on the master cylinder critical to correct operation?
I should have stated up front that I'm a noob. You probably figured that out after reading this rambling post. So, I welcome everyone's ideas and suggestions. The truck does not currently run. I'm working on the brake system now. I have a new wire harness that I hope to install this winter and I hope to install my spare (and running) 235 this spring and actually have my truck move under its own power. I'm doing it this way because I know if I install the 235 now I'll want to drive it. Stopping is important, that's why I'm doing the brakes first. So I want to get it right and appreciate everyone's help!
Thanks,
Mike
OBTW, There are tons of pictures of what I've done with the brakes at my photobucket page and on my blog.
