$tingray

All new calipers, lines, and master cylinder on a '70 Corvette. Ready to bleed the brakes.

Bench blead the master cylinder.

Using vacuum bleeder, I can suck fluid at all bleeder valves except the left front.

The rear (left and right) bleeds fine out both valves when pumping the brakes.

The front right bleeds using vacuum, but can't get to bleed when pumping brakes.

Can't get the left front to bleed by vacuum or pumping brakes.

Does anyone know what could be causing this? I have blead many brakes, but have never run into this problem.

'75

It may be a bad new hose, blocked on the inside. I would check to see where fluid stops by loosening the connections.

merc49

loosen the lines starting at the master and work your way to the problem area.have someone hold the pedal down while you crack the lines open and see what kind of flow you get.could be a bad distribution block a pinched hard line or a bad hose which i have had before,i always blow thru them before installing after the last fiasco.i have also had rebuilt masters that were bad but you said you got fluid to three wheels so that makes one think its o.k.

Bagpype

Had the same problem on my 78's driver side rear after a complete brake system overhaul including new master and lines. We just kept pressing the pedal for what seemed like forever and finally the fluid started to flow. For a while i was sure something was bad but we finally got it working by diligent bleeding.

builder

I open one valve on one caliper at a time. Make sure the master is full. Let gravity take over. Get a cup of coffee. When it drips steady, close it up and go to the next caliper, and so on, till all 4 are wet. Then I go to the 2 man method of one man pumping and the other opening and closing the caliper bleed valve. If power brakes, I do it with the engine running.

blueray72

Don't forget to check the prop valve.

AdamMeh

Had a former brake shop owner help me with the brake system rebuild on our '77. He insisted on using a pressure bleed system (plate on top of the master cylinder - air charged) instead of vacuum. Said he would not use a vacuum bleed on a Vette as you can not get all of the air out of the system. Wish I had more details to share (or the knowledge to understand it lol) about this theory, but the brakes on our car are amazing.

Adam

glackore

Air or a restriction is the culprit. If the master has been bench bled and shows no more air, there is either air in the front lines/calipers or a restriction. You didn't mention brake hoses in your post - did you repalce them? If not, I'd do it while you have the rest of the system apart. Go with SS hoses for sure. The other postings have good ideas as well - gravity, air pressure vs. vacuum, etc.

Gary

$tingray

Thanks for all ideas. I now have calipers leaking around the pistons. I'm going to buy an O-ring upgrade kit and replace all the lip seals and just start over bleeding. Thanks again.

Dallas

mds3013

This is what I did. Gravity is your friend. If you need any help, just ask. mike...

http://forums.corvetteforum.com/c3-g...-calipers.html