bleeding a dry brake system 73
Thread Starter
Burning Brakes
Joined: Aug 2002
Posts: 926
Likes: 2
From: chandler az
bleeding a dry brake system 73
Does anyone have any good tips for getting all the air out. This car was parked for 20 years and the brake lines were dry when I started work on it. Everything but the proportioning valve is new.
I makeshifted a powerbleeder to get fluid to all the new calipers - then did the normal pump and I started at the passenger rear and bled at all of the corners(new calipers filled prior to install) until no more air came out. I also primed and bled the new master cylinder . I still can not get a firm pedal. What am I overlooking? :confused:
I makeshifted a powerbleeder to get fluid to all the new calipers - then did the normal pump and I started at the passenger rear and bled at all of the corners(new calipers filled prior to install) until no more air came out. I also primed and bled the new master cylinder . I still can not get a firm pedal. What am I overlooking? :confused:
Burning Brakes
Joined: Nov 2001
Posts: 1,191
Likes: 1
Re: bleeding a dry brake system 73 (brookman)
I'm sure you checked the obvious, but just in case.....
1 - Did you bench-bleed the master cylinder before installation?
2 - Are there any fluid leaks along the lines or at the junction blocks?
I would have bled the lines after attaching the master cylinder and before attaching the flexible hoses to the calipers.
1 - Did you bench-bleed the master cylinder before installation?
2 - Are there any fluid leaks along the lines or at the junction blocks?
I would have bled the lines after attaching the master cylinder and before attaching the flexible hoses to the calipers.
Thread Starter
Burning Brakes
Joined: Aug 2002
Posts: 926
Likes: 2
From: chandler az
Re: bleeding a dry brake system 73 (markdtn)
I haven't tried tapping the calipers. I am aware of the two bleeders on the rear calipers. I did do what was suggested above. I installed the master cylinder - bench bled it - then used vacuum to pull fluid to the wheels. I have only done all 4 wheels once. Tonight I will put it up on jackstands and do it again.
Le Mans Master
Joined: Aug 2000
Posts: 9,662
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From: Semper ubi, sub ubi
Cruise-In VI Veteran
Cruise-In VII Veteran
Re: bleeding a dry brake system 73 (brookman)
Don't vacuum bleed it. I have never heard of anyone actually sucessfully using a vacuum pump for anything other than flushing or filling a system. The problem is covette caliper pistons and seal, they will suck air if you apply a vacuum.
You need to gravity bleed the brakes. You gravity bleed by getting a tight piece of tygon(plastic tubing) and slipping it over the bleeder, run the tubing down into a jar with brake fluid in it. Make sure the end of the hose is under the fluid.
Jack up the rear of your car, make sure your master cylinder is full and gravity bleed the right rear caliper. Tap on the calipers to dislodge air bubbles. Do both bleeds inside then outside.
After all the bubbles are out tighten the bleeder and do the left rear.
Lower the rear of the car.
Now do the passenger side then the driverside fronts.
When everything is bled the brakes should be hard as a rock. If not then you still have air in the system.
You need to gravity bleed the brakes. You gravity bleed by getting a tight piece of tygon(plastic tubing) and slipping it over the bleeder, run the tubing down into a jar with brake fluid in it. Make sure the end of the hose is under the fluid.
Jack up the rear of your car, make sure your master cylinder is full and gravity bleed the right rear caliper. Tap on the calipers to dislodge air bubbles. Do both bleeds inside then outside.
After all the bubbles are out tighten the bleeder and do the left rear.
Lower the rear of the car.
Now do the passenger side then the driverside fronts.
When everything is bled the brakes should be hard as a rock. If not then you still have air in the system.
Tech Contributor
Joined: Aug 1999
Posts: 15,166
Likes: 3,968
From: Connecticut, USA
Re: bleeding a dry brake system 73 (brookman)
I would double check your connections for a leak. Do youhave the correct M/C? there are 2 types 1- PB 1- non PB.
Did you change the rubber hoses and the copper washers on the front calipers?
Did you have a firm pedal until you drove the car a short distance? If so, then you may have rotor runout causing the calipers to pump air into the system. VERY common problem with these cars. Make sure your runout is under .003" front and back rotors,also check the rear bearings as they too can contribute to this problem. Do a search of the archives and you'll find a LOT of info on this.
Good Luck,you'll find it there's only so many reasons for your problem.
Gary
Did you change the rubber hoses and the copper washers on the front calipers?
Did you have a firm pedal until you drove the car a short distance? If so, then you may have rotor runout causing the calipers to pump air into the system. VERY common problem with these cars. Make sure your runout is under .003" front and back rotors,also check the rear bearings as they too can contribute to this problem. Do a search of the archives and you'll find a LOT of info on this.
Good Luck,you'll find it there's only so many reasons for your problem.
Gary
Thread Starter
Burning Brakes
Joined: Aug 2002
Posts: 926
Likes: 2
From: chandler az
Re: bleeding a dry brake system 73 (gtr1999)
I haven't even driven the car yet. The front hoses were not replaced. There are no visible leaks. I didn't even think about the possibility of the vacuum pulling air through the caliper. I will try the gravity bleed . Thanks for all the responses.
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Melting Slicks
Joined: Mar 2001
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From: Lake Villa IL
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St. Jude Contributor
Re: bleeding a dry brake system 73 (brookman)
Check my website for brake bleeding tips. So far, my method has always worked for me. And it's a lot quicker than gravity bleeding...
Thread Starter
Burning Brakes
Joined: Aug 2002
Posts: 926
Likes: 2
From: chandler az
Re: bleeding a dry brake system 73 (joeveto)
well it is all fixed now. I went out this morning to a puddle of brake fluid under the driver rear caliper. I replaced it and all is well. Thanks all.
Navigator
Joined: Jul 2003
Posts: 9
Likes: 0
From: Brunswick Ga
Re: bleeding a dry brake system 73 (brookman)
Hmmm. I don't think you will ever get all the air out and keep it out that is. After sitting dry for that long you will most likly need to at least rebuild the calipers. Mine sat for 3 years and I got sick of the air problems and purchased new calipers from VBP and got the o-ring design. Best move after fighting air over a year.
