79vetter

I took all 4 calipers off to rebuild them and now am getting to the bleeding part of this job. I am pushing on the pedal and my buddy is watching the tube from the bleeder into the submerged can of fluid. We cannot seem to get rid of the air in the system because we are never getting a steady stream of brake fluid. Our bleeder hose seems like a good fit and none of the other calipes are leaking.
Could it be that my Master Cylinder is introducing air every time I press on the pedal? The reason that I ask is because I get a bubble in the M/C every time I press the pedal down (from the forward compartment in the M/C). I did bench bleed it.
Any other suggestions?

thanks Rob

tracdogg2

Rob,
You've got an air pocket in the master cylinder. Jack the back end up higher until the master cylinder is pointing downhill. Start with bleeding just the left front until you get fluid flowing. Then do the left rear. Then try gravity bleeding the rest of it. You'll need to jack the back of the around to get all the air out of the rear calipers.
Mike

...Roger...

Take the master cylinder back off and bench bleed again -this time really really good and then dont pump anymore just gravity bleed.

79vetter

When you guys say gravity bleed, are you doing everything that I am doing above except you don't push the pedal to force the air out?
thanks

...Roger...

Yes-----I go around with a brass drift punch and tap lightly all fittings and lines as the fluid is flowing to dislodge any air.If your going to use your tube in the fluid method you'll have to seal the threads around bleeders.If you dont you'll pull air in around threads.And with your method -pump ever so slowly-or you'll make foam.

79vetter

With the gravity method, do you still have the tube in the can of fluid for each bleeder screw? you just aren't pumping the pedal?

My problem is that I don't ever get a flow starting. Should a flow start happening as soon as open the bleeder? In addition to the taps that you mentioned?
I jacked up the rear as such that it is higher than the front. I then tried to get a flow going on the front left caliper but it seems to push air/fluid when I push the pedal in --- and when I release the pedal it seems to suck it right back in. So I never get that constant solid fluid flow...

...Roger...

If you want to use that method push pedal down close bleeder let pedal up open bleeder push pedal down close bleeder and repeat-that will keep fluid from returning to caliper

jaki30

When I did a body off on my 72, I used a hand held vacuum pump to bleed the system down one caliper at a time. Worked excellent. Just make sure the proportioning valve stays open. If it swings to one side, you won't get any more fluid out of those two calipers.
Another option, open all the bleeders and let them stay ope for at least 24 hours. Keep the M cyl filled and they will almost self bleed.
The vacuum pump works really great and you can pick one up for about $40

gliot1

The problem most common when bleeding is improper sequence. C3 Corvettes run a different bleed sequnce than most cars. If you do it right you have a great chance of a hard pedla in one or two passes. I have dealt with this a number of times. Double check the GM shop manual, but off the top of my head it is LR, RR, LF, RF. It is not farthest to closet like most cars.

gerry72

That's the correct bleeding order, but from what he's describing the master hasn't been bled out. I had to do mine this weekend after overhauling the diff and the suspension and since the master went dry I had to bleed it out before doing the calipers. It never works if you don't bleed the master cylinder first.

ccs96

79vetter

I did bleed the Master Cylinder first. Perhaps I didn't do it right --- but I just put it into a vise, filled it with fluid and ran the 2 hoses back up and into the fluid. I then pressed on it several times. There was always one small bubble that would come up and I could not get it to vanish no matter how times I bled it.
I then mounted it with the fluid still in it.

...Roger...

I spend no less than 15 min. bench bleeding.I push,I tap I pump I push 1/2 way, I stroke back in forth in the middle ,I stroke only in the first 1/4 inch,I stroke all the way,I stroke with my left foot off the floor,I push with my left hand behind my back,I let it sit for a few min.and come back and tap on it and push some more.Yes you can get every last bubble out of it-YOU MUST- if you dont or you cant then you wont have the best brakes that you can have.If you cant get all the bubbles make sure your bleeder hoses arnt leaking if thats not it get another cylinder.It is extremely hard if not impossible to get air out of the cylinder when mounted on the car even with a power bleeder.I know I'm gonna catch it by the power bleeder guys but I've tried all ways and I learned a good bench bleed is your friend.

Avette4me

pressure is the only way in my opinion....

69autoXr

I've never found the bleed order to make a difference, even when starting with empty calipers. I've been doing it furthest to closest all my life, so has every other racer C3 guy I know and it's never been a problem.

...Roger...

But I do like starting with the drivers side and clearing that side of all air.If there is a little air left at the junction after bleeding the pass side its a shorter distance to then open the drivers side and get it out rather than drag it clear across to the pass. side.