Chevy Nova Forum banner

1 - 18 of 18 Posts

·
Registered
Joined
·
95 Posts
Discussion Starter #1
I just started bleeding all four corners with a mityvac vaccum pump. The system is 100 percent new so everything was dry. I did bench bleed the master first. Should i still do the manual pump and hold method of bleeding brakes after I vacuum bleed them?
 

·
Registered
Joined
·
95 Posts
Discussion Starter #2
Edit....
I vacuum bled all 4 corners and the pedal is mush!!!!! Zero resistance at the pedal. Restart the bleeding process? I did bench bleed the master and all seemed well
 

·
Registered
Joined
·
189 Posts
I have run across that a couple times with a dry system. A couple things worth trying.

1. With the one of the bleeders open pump the pedal a few times leaving the bleeder open, then let it gravity bleed. Start at the closest wheel and work your way out from there. You will need to re-bleed the master. Once you have fluid to all the wheels. Then bleed like normal.

2. Take the master cap off crack the bleeders at the wheels and let it gravity bleed.

Sometimes even pulling with vacuum doesn't help with a dry system. Keep at it, you'll get fluid eventually.
 

·
Premium Member
72, 2 Dr, 383, 700r4
Joined
·
1,336 Posts
Cap off, but pay attention to the fluid level as you go. You will need to keep adding so the master does not run dry and start sucking air. Same with gravity bleed, keep the fluid level up no need to re-bleed the master as long as you pay attention to the fluid level. I bled my new dry system with a mighty vac but it was a long day. Could hardly move my hand when it was over. I always thought you start at the closest wheel to the master.
 

·
Registered
Joined
·
95 Posts
Discussion Starter #7
Well I gravity bled all four corners. The front calipers had a slow but stready stream and the rears had a very very slow drip after at least an HR. The pedal is still completely mush, zero resistance. Keep gravity bleeding rears till I get more fluid out or re bench bleed the master????
 

·
Registered
Joined
·
13 Posts
One issue with vacuum bleeding is air leakage. You need to use the grease around the threads of the bleeder fitting. With the master bled, the procedure that I have used is to start with the furthest wheel from the master and then work closer to it. I actually prefer to pressure bleed, here's my recent home made bleeder that I use now:

 

·
Registered
Joined
·
95 Posts
Discussion Starter #9
Update, to rule out the master cylinder I pulled the lines out of the master and plugged them. I pushed the pedal and it was firm. I was super happy about this So I put it back together and proceeded. I used the advice above and got a better seal around the brake bleeders. Instead of grease I used plumbers putty. Less mess and worked great! It allowed no air to suck past the threads of the bleeders and held a perfect vacuum. I got tons of air out of all four corners before I ran out of fluid. The pedal is much better than before but a long ways from rock solid. Once I get more fluid I'll probably continue the bleeding process using the pump and hold method.
 

·
Registered
1972 Nova
Joined
·
344 Posts
From using a Mityvac on my Nova and my truck, I've found that I like it to move fluid when replacing lines or components (calipers, wheel cylinders, etc.), but nothing beats the pump and hold method to make sure the air is gone (my dad is a believer in gravity bleeding, but I haven't tried that yet. A quick Google search makes it sound like that's a better method for just replacing fluid, not bleeding).
 

·
Registered
Mike - 74 Nova Baltimore, MD
Joined
·
1,534 Posts
Once I get more fluid I'll probably continue the bleeding process using the pump and hold method.
When using the pump and hold method, push the brake pedal slowly to induce the pressure.... rapidly pumping the brake pedal during brake bleeding could cause aeration of the fluid within the master cylinder.
When holding the pressure on the brake pedal while bleeding... then turning the bleeder valve to release the fluid/pressure and the brake pedal goes to the floor, continue to hold the brake pedal on the floor until the bleeder valve is closed... and then raise the pedal. This step keeps you from sucking air into the system thru the bleeder valve threads.

Repeat steps (slowly pump pedal > hold > open bleeder valve > close bleeder valve > release/raise pedal) until all air is gone and move the the next cylinder.
 

·
Registered
Joined
·
570 Posts
I use teflon tape on the bleeder screws, but plumbers putty is a good idea. One problem I ran into with the mityvac, is that if you have a leak anywhere, the vacuum method will continue to suck air in at the leak. That can be frustrating.
 

·
Registered
Joined
·
95 Posts
Discussion Starter #14
The putty definitely sealed up all the leaks. It would hold 20 in of hg no problem. After I vacuum bled each corner very thoroughly I manually bled each corner with the pump and hold method. I bled about 6 pints of fluid through, maybe more. The pedal never got firm as I was expecting. The place I bought the kit from was very very helpful. He explained to me that with a 7/8" master I can expect a longer stroke and softer pedal. I may need to move up to a 15/16" master. Unfortunately this time of year is pretty yucky in WI so I won't know till next year. Rats
 

·
Registered
Joined
·
570 Posts
The putty definitely sealed up all the leaks. It would hold 20 in of hg no problem. After I vacuum bled each corner very thoroughly I manually bled each corner with the pump and hold method. I bled about 6 pints of fluid through, maybe more. The pedal never got firm as I was expecting. The place I bought the kit from was very very helpful. He explained to me that with a 7/8" master I can expect a longer stroke and softer pedal. I may need to move up to a 15/16" master. Unfortunately this time of year is pretty yucky in WI so I won't know till next year. Rats
Just for your reference, I have a '63 with manual brakes, S10 disc in front and drum in rear. I am using a 1969-ish Corvette 1" master and it's just right. I also have an adjustable proportioning valve in the line going to the rear brakes. Do you have disc in front and drum in rear? Are your drum brakes properly adjusted?
 

·
Registered
Joined
·
95 Posts
Discussion Starter #16
Yes I have disc in the front and drums in the rear. I know having the drums fairly right helps. I even tightened them up a bit more hoping to notice a difference. I think the 1" master is what I will need
 

·
Premium Member
72, 2 Dr, 383, 700r4
Joined
·
1,336 Posts
I used the MityVac for years until I learned about the Phoenix Systems brake bleeder. It pushes fluid thru the system rather than suctions it. A lot less work with a very well bled brake system.
I think that's where I'm headed. Couldn't move my hand after Mighty Vac. I was sucking air forever till a realized it.
 
1 - 18 of 18 Posts
Top