Air in brake lines

54olds · October 30th, 2007, 09:40 AM

I have a '54 olds 88 with the treadlevac master cylinder. I've been trying to bleed the brakes, but I cannot seem to get the air out of the lines. I spent about two hours yesterday evening bleeding at each wheel, but all I seem to get is air with just a dribble of brake fluid.

There are no fluids leaks, and I made sure the master cylinder was kept full of fluid. There is fair pressure at the two front wheels (you can see the pulse of air whenever the pedal is pushed), but only a little at the two rears. Either way, no matter how many times I've tried, all I get is air.

I'm kinda stumped here, so if anyone has any idea what I should check next, I would appreciate it!

Dapapadon · October 30th, 2007, 12:38 PM

I've been using a vacuum bleeder like Mity-Vac. When I changed the rearend on my 66 I vacuum bleed the rear brakes. Then bleed them normal about twice each wheel 'cause I wanted to be sure. No issues with the brakes since. And it only took about 30 minutes. Plus the rear was out of the car about 3 weeks, with the line plugged.
Don

54olds · October 30th, 2007, 01:48 PM

Could there be anything wrong with the master cylinder that would cause it to pump air and not brake fluid? I've heard recommendations that the master cylinder should be bled, but I didn't see a place on the treadle vac where you could do that.

kevinkpk · October 30th, 2007, 03:27 PM

Quote:

Originally Posted by 54olds

Could there be anything wrong with the master cylinder that would cause it to pump air and not brake fluid? I've heard recommendations that the master cylinder should be bled, but I didn't see a place on the treadle vac where you could do that.

I'd say your sucking air from somewhere, if you pump up the brake pedal, does it go anything but to the floor? If it will not pump up after opening the blled valves with pressure on the brake pedal, I'd say look at all the wheel cylinders, if you have a leak there you will know it. Vaccum bleeders have been around a long time, but I still like the manul bleed with two guys and pumping the brake pedal.

kevinkpk · October 30th, 2007, 03:32 PM

One other thing, if you are holding the brake pedal down to the floor after the bleed valve is shut, and still having this problem, could be a bleeder valve not closing off. Also could be a master cylinder bleeding fron the front to bake brake or vise versa internally. But you say you are having air, so I'd look at either wheel cylinders or bleeder valve.

88 coupe · October 30th, 2007, 09:15 PM

Quote:

Originally Posted by 54olds

........ treadlevac master cylinder ........ ........ cannot seem to get the air out of the lines ........

Try it with the engine running.

Norm

ozoneblue · October 31st, 2007, 04:37 PM

Had the same problem with my 54 I put new bleeders in slid a hose over them & pulled a vac with my AC vac pump still took forever

54olds · October 31st, 2007, 07:43 PM

I think I'll try a Mity-Vac and see if I can force the fluid through the lines. When you pressurize the master cylinder, should you have the brake pedal depressed?

Dapapadon · October 31st, 2007, 08:24 PM

It's vacuum, it attaches to the other end on the bleeder. I leave the cap off the master, check the bleeder to make sure it's not too tight, attach the vacuum hose to the bleeder (w/ adapter), pump the vacuum up and slowly open the bleeder. I get air, then fluid & air and finally just fluid. Tighten the bleeder before removing the hose. Check the fluid level in the master cyclinder then go to the next wheel.

I usually don't have to do anything to the pedal while I do this. Put it sounds like this particular system may be tricky. You might have someone at the pedal while you do the vacuum bleed. Maybe try light pressure and release or "Slowly" pumping, but not too much pressure on the pedal.

I always bleed each wheel the old fashion way, usually right after I vac. bleed each.

You asked about bench bleeding the master cyclinder on the car. What I done before is have someone pump and hold pressure on the pedal, then loosen the brake line at the master cyclinder, repeat till you have good fluid flow. But remember, brake fluid removes most paints. Maybe have a shop rag or something over your hand & wrench as you try this.

Don

October 30th, 2007, 09:40 AM	#1 (permalink)
54olds Nothing new beats an Olds Join Date: Aug 2007 Location: Illinois Posts: 96	Air in brake lines I have a '54 olds 88 with the treadlevac master cylinder. I've been trying to bleed the brakes, but I cannot seem to get the air out of the lines. I spent about two hours yesterday evening bleeding at each wheel, but all I seem to get is air with just a dribble of brake fluid. There are no fluids leaks, and I made sure the master cylinder was kept full of fluid. There is fair pressure at the two front wheels (you can see the pulse of air whenever the pedal is pushed), but only a little at the two rears. Either way, no matter how many times I've tried, all I get is air. I'm kinda stumped here, so if anyone has any idea what I should check next, I would appreciate it!

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October 30th, 2007, 12:38 PM	#2 (permalink)
Dapapadon Registered User Join Date: Jan 2007 Location: Portland, OR Posts: 361	I've been using a vacuum bleeder like Mity-Vac. When I changed the rearend on my 66 I vacuum bleed the rear brakes. Then bleed them normal about twice each wheel 'cause I wanted to be sure. No issues with the brakes since. And it only took about 30 minutes. Plus the rear was out of the car about 3 weeks, with the line plugged. Don

October 30th, 2007, 01:48 PM	#3 (permalink)
54olds Nothing new beats an Olds Join Date: Aug 2007 Location: Illinois Posts: 96	Could there be anything wrong with the master cylinder that would cause it to pump air and not brake fluid? I've heard recommendations that the master cylinder should be bled, but I didn't see a place on the treadle vac where you could do that.

October 30th, 2007, 03:32 PM	#5 (permalink)
kevinkpk Senior Member Join Date: Oct 2007 Location: west Posts: 211	One other thing, if you are holding the brake pedal down to the floor after the bleed valve is shut, and still having this problem, could be a bleeder valve not closing off. Also could be a master cylinder bleeding fron the front to bake brake or vise versa internally. But you say you are having air, so I'd look at either wheel cylinders or bleeder valve.

October 31st, 2007, 04:37 PM	#7 (permalink)
ozoneblue Registered User Join Date: Jun 2006 Posts: 503	Had the same problem with my 54 I put new bleeders in slid a hose over them & pulled a vac with my AC vac pump still took forever

October 31st, 2007, 07:43 PM	#8 (permalink)
54olds Nothing new beats an Olds Join Date: Aug 2007 Location: Illinois Posts: 96	I think I'll try a Mity-Vac and see if I can force the fluid through the lines. When you pressurize the master cylinder, should you have the brake pedal depressed?

October 31st, 2007, 08:24 PM	#9 (permalink)
Dapapadon Registered User Join Date: Jan 2007 Location: Portland, OR Posts: 361	It's vacuum, it attaches to the other end on the bleeder. I leave the cap off the master, check the bleeder to make sure it's not too tight, attach the vacuum hose to the bleeder (w/ adapter), pump the vacuum up and slowly open the bleeder. I get air, then fluid & air and finally just fluid. Tighten the bleeder before removing the hose. Check the fluid level in the master cyclinder then go to the next wheel. I usually don't have to do anything to the pedal while I do this. Put it sounds like this particular system may be tricky. You might have someone at the pedal while you do the vacuum bleed. Maybe try light pressure and release or "Slowly" pumping, but not too much pressure on the pedal. I always bleed each wheel the old fashion way, usually right after I vac. bleed each. You asked about bench bleeding the master cyclinder on the car. What I done before is have someone pump and hold pressure on the pedal, then loosen the brake line at the master cyclinder, repeat till you have good fluid flow. But remember, brake fluid removes most paints. Maybe have a shop rag or something over your hand & wrench as you try this. Don