Problem bleeding brakes

[zzrodder]

I'm having a real problem getting the brakes to bleed. I bench bled the master and also got a Mighty Vac tool to pull the fluid through to each corner but I can't get it to push any fluid to the front or rear at all. It's driving me nuts !!
I've installed the usual Wilwood 2lb. front and 10lb. rear residual valves (the rear one is not visible, hidden behind the exhaust heat shield). The only thing I can think of is that the residual valves are preventing the master from pushing enough fluid through to build pressure to bleed out the air??[S
I'm considering making a plate to mount to the top of the master with an air fitting on it so I can use the compressor to pressurize it and force bleed it...
Good idea or bad ??

 

[offroadrolls]

Residual valve's not in backwards is it? I only ask because it's something I'd do.[S

 

[zzrodder]

Residual valve's not in backwards is it? I only ask because it's something I'd do.[S

Nope, double checked them, though I'm thinking to remove them and put in some temporary couplings to see if it that works....

 

[jmlcolorado]

I would try removing your valves like you mentioned. If that doesn't work, go the next messy step and unhook the lines from your master and see if you get fluid out the outputs. If you do, then hook the lines back up and work your way down the lines to each union or other connector.

If your not getting fluid to either, I would guess the bench prime didn't do it's job.
I hate priming empty master cylinders. Seems you gotta do. Ore work then is needed to get them primed well.

 

[GJunktionMike]

I posted to your build thread before i saw this thread. Some thing that I do when starting with dry lines is fill the master. Then with a hand vac pump attached to the bleeder (make sure it is cracked open) start at one and work your way around. closing each bleeder when done with that bleeder (I have left one open before, redo). This works real well to fill the lines but like I posted on your thread sometime a high spot in the line gives you problems.

 

[zzrodder]

I actually have bench bled the master twice - before starting the rest of the bleeding, then I took it off and bled it again.
I've already used the hand vac pump (see pic). I can draw fluid at all 4 corners (done it several times at each wheel) but still no amount of pumping the pedal will push any fluid out of the bleeders.
There may be something to the idea of air staying in the high spots in the lines... that's why I'm thinking about pressurizing the master to force the fluid through -

 

[sneakysnake]

If you have vacced fluid through the line most of the air should be gone.When you pump the pedal several times are you getting any buildup at all?Are the shoes adjused out close to drum? When you bench bled it were you getting a strong stream?As a last resort you could make up a couple of plugs and cap the outlets to see if the master is internally bypassing for some reason.

 

[sneakysnake]

One other thing, the plunger has to come all the way back for the fluid to enter the chamber,make sure your pedal travel is letting the master make a full stroke or after one pump no more fluid can enter.

 

[Old Iron]

I used a male 1/4 in air hose quick connect drilled a hole in the top of an old master cyl cover and threaded it for the fitting to screw into.
Turn the compressor regulator down all the way, put the cover on the master cyl and hook the air hose to the fitting, turn the regulator up till I got 15 psi then run all the bleeders.
Worked fantastic with the best brakes I've ever had.

 

[jmlcolorado]

I used a male 1/4 in air hose quick connect drilled a hole in the top of an old master cyl cover and threaded it for the fitting to screw into.
Turn the compressor regulator down all the way, put the cover on the master cyl and hook the air hose to the fitting, turn the regulator up till I got 15 psi then run all the bleeders.
Worked fantastic with the best brakes I've ever had.

This sounds like a winning tech tip that should have a solid write up with photos, then added as a sticky in the tech thread!
thanks!!

 

[EnglishBob]

Princess auto have a pneumatic bleeder system which works really well and seems to iron out little problems like this for me.
http://www.princessauto.com/pal/product/8261638/Brakes/Pneumatic-Brake-Bleeder-Kit

 

[42chevy]

What about the rod between the booster and master cylinder? I had one I had to get an adjustable pushrod.

 

[zzrodder]

What about the rod between the booster and master cylinder? I had one I had to get an adjustable pushrod.

Bingo ! Give the man a medal !
I actually came to this conclusion this afternoon after pressure bleeding still did not produce results.
The booster/master combo I bought for this car is missing the proper extender rod between the booster plunger and master. It has a threaded tip on the booster so I'll machine a proper intermediate rod to fit. A little measuring showed me the booster rod was only moving the master cylinder plunger about 1/16" !!
I made a plate this morning with an air fitting to pressure bleed it (googled it last nite) and some gaskets made from some rubber pond liner (!!). First try with it held down by the wire holders and a couple shims rewarded me with a lovely spray of brake fluid everywhere. ARRGGHH ! Then I used C clamps and it worked great with 20psi. Fluid pushed out to all 4 corners. When that still didn't get results pumping the pedal, the light bulb finally came on and I removed the booster to find out what 42Chevy had guessed.

Thanks all for the help ![cl