More Brake Woes

[Bwmurph]

Well, after finally getting (one side) or my Parking Brake squared away I now find that my left rear (Driver Side) caliper is leaking like crazy. This has just started, so I obviously did something to it while working on the Parking Brake. Not sure what I did to it, but when I was re-isntalling the caliper I could here and see it sucking air at one (or more) of the pistons.

I took it for a spin to make sure everything was OK and I had jsut abou tzero brakes. So I decided to bleed the system with the Motive Power Bleeder I bought some time ago, I pull off the left rear tire and the wheel and tire are soaked in brake fluid. Can't see exactly where it's coming from, but I assume it's coming out of one or more of the pistons I heard/saw leaking air. So I'm probably gong to run down to the local auto parts store and buy a caliper.

ANother thing I noticed when getting ready to bleed the brakes: I looked through the Haynes manual (in another thread I reffered to this as a Chiltons manual, my bad) and they say to blead the brakes in the following order: Left Rear, Right Rear, Left Front, Right Front.

I always thought you started at the brake furthest fromt he master cylinder and worked your way back. Can anyone shed any light on this ?

Thanks,

Bernie O.

 

[Bwmurph]

I'm beginning to feel like an idiot. I put the new caliper on the left rear barke yesterday; no problem wne tright on.

Then went to power bleed the brakes with the Motive Power Bleeder. Everything is going along fine (I thought) and I was really happy with how fast and easy the process is. THen as I'm just finishing up on the right front brake I notice all my brake fluid running under the car. I'm not sure if I over-pressureized the system or if my clamp (I'm not using the chains supplied with the system) came loose.

So I stop the leak, decide to finish bleeding the brakes (only have one left to do) and then clean up the mess. I clean the mess up and figure that's the worst of it. Then I get in the car and I have no pedal at all.

So what's gone wrong here ? When I sprung the leak did I pump air back into the system ? Did I over-pressurize the system and damage something else ? The instuctions say not to go over 20 psi so I kept it to about 15 psi; is this too much ? WHat about the inner and outer bleeders on the calipers ? I was only bleeding the outers as I thought that's all that's required on a '71.

Any pointers woudl be greatly appreciated,

Bernie O.
Any help would be greatly appreciated

 

[6880 Mike]

You will have to determine the source of your leak and repair that. Once the leak is remedied, bleed the system.

On the rears, bleed inner half first, then the outers.

 

[Bwmurph]

Mike,

I'm 99.9% positve the leak was at the plate from the Power Bleeder that goes over the Master Cylinder.

Any idea wht type of pressure I should be using with the Motive Power Bleeder ?

 

[TMPJoe]

I never use a power bleeder on old cars. (Actually dont on new ones either for that matter)

The air gets past the pistons.. I would bleed them manually

 

[White75]

I never use a power bleeder on old cars. (Actually dont on new ones either for that matter)

The air gets past the pistons.. I would bleed them manually

I agree with this. Manually bleed them. I got the bleeder screws with the valve in them so it can still be a 1 person job but after much problems with a powerbleeder that put more air into the system, I gave up.

 

[Bwmurph]

Well I finally got it all complete. The brakes actually work and I've got a "harder" pedal than I ever have had with this car.

Basically, I stared all over again with bleeding the brakes. I hooked up the power bleeder jsut as I did the first time with a single C-clamp to hold the plate on the master cylinder. INstead of using 15 psi, this time I vowed not to go over 10 psi. I bleed the inners and outers on the rear wheels, then move to the front, carefully checking the pressure. Everything is going fine until I get to the last caliper (left front). Again, I start to see brake fluid leaking. It's not as bad as the first time, and I'm reasdy for it this time with catch pans, buckets, rags, etc..... I (finally) notice that it's coming from the rear of the master cylinder where the plate is. I also notice that the plate is up against the hold down clip that holds the factory lid on the master cylinder. It seems to have "sucked down" during the bleeding process, but the hold down clip is in the way to let it completely seal. I pull the clip off, tighten the plate back down and finish bleeding the last brake..

I finish up, clean the (small) mess up, and test drive the car. It now has better brakes than it ever has since I've owned the car.

Bernie O.

 

[Vette79]

Well I finally got it all complete. The brakes actually work and I've got a "harder" pedal than I ever have had with this car.

Basically, I stared all over again with bleeding the brakes. I hooked up the power bleeder jsut as I did the first time with a single C-clamp to hold the plate on the master cylinder. INstead of using 15 psi, this time I vowed not to go over 10 psi. I bleed the inners and outers on the rear wheels, then move to the front, carefully checking the pressure. Everything is going fine until I get to the last caliper (left front). Again, I start to see brake fluid leaking. It's not as bad as the first time, and I'm reasdy for it this time with catch pans, buckets, rags, etc..... I (finally) notice that it's coming from the rear of the master cylinder where the plate is. I also notice that the plate is up against the hold down clip that holds the factory lid on the master cylinder. It seems to have "sucked down" during the bleeding process, but the hold down clip is in the way to let it completely seal. I pull the clip off, tighten the plate back down and finish bleeding the last brake..

I finish up, clean the (small) mess up, and test drive the car. It now has better brakes than it ever has since I've owned the car.

Bernie O.

I purchased two new rear calipers and lines from VB&P. Did the install. Used the Power Bleeder three times. No air in the system. Brake pedal goes to the floor with little resistance. No leaks. It's not the Booster because it's hard when motor is not running. I'm thinking Master Cylinder. Any suggestions?
As for the Power Bleeder, the trick is to use a 8'' piece of 2x4 piece of wood over top of the rubber plate that goes on top of the master cylinder and then use the c-clamp. This distributes the pressure evenly. We had the same problem with brake fluid being pushed out the back of the reservoir. The 2x4 eliminated that problem.

 

[Bwmurph]

I'm certainly no expert, so take everything I say with a grain of salt or two.

Did you make sure to bleed both the inner and outer bleeders ? I did right rear inner, right rear outer, left rear inner, left rear outer, right front, left front.

Also, when you're bleeding the brand new calipers, take a small hammer and keep tapping the front, back and all over the caliper. This will help dislodge some of the air trapped in the caliper. You'll be amazed out how much more air will come out of it !

Was the Master Cylinder acting up before the purchase of the calipers ? If it wasn't bad before you started It probably isn't bad now. Although, stranger things than that will happen with these cars !!

Also, I used about 9 - 10 psi on the Power Bleeder (tried 15 psi earlier and think it was too much).

Good luck and at least you didn't drop 1.5 quarts of brake fluid on your drivewa, or did you ?

Where's Millersville ?

Berie O.

 

[Vette79]

I'm certainly no expert, so take everything I say with a grain of salt or two.

Did you make sure to bleed both the inner and outer bleeders ? I did right rear inner, right rear outer, left rear inner, left rear outer, right front, left front.

Also, when you're bleeding the brand new calipers, take a small hammer and keep tapping the front, back and all over the caliper. This will help dislodge some of the air trapped in the caliper. You'll be amazed out how much more air will come out of it !

Was the Master Cylinder acting up before the purchase of the calipers ? If it wasn't bad before you started It probably isn't bad now. Although, stranger things than that will happen with these cars !!

Also, I used about 9 - 10 psi on the Power Bleeder (tried 15 psi earlier and think it was too much).

Good luck and at least you didn't drop 1.5 quarts of brake fluid on your drivewa, or did you ?

Where's Millersville ?

Berie O.

We used no more then 12psi and I think the master cylinder was acting up before the caliper replacement but not sure as I had a leaking piston on the rear drivers side caliper which caused low fluid level and turned the fluid milky. Could have destroyed my master cylinder or maybe it just needs to be bench bled.
Millersville is North of Crofton and Annapolis and South of Baltimore and Glen Burnie.

 

[JohnZ]

Also, I used about 9 - 10 psi on the Power Bleeder (tried 15 psi earlier and think it was too much).

10-15 psi is fine - the caution about using more pressure is to avoid having the hose blow off from the bottle to the adapter plate and blowing pressurized brake fluid all over your shiny paint (you can't over-pressurize the brake system with the power bleeder - it's tested at the plant after bleeding at 2,000 psi).

 

[Vette79]

10-15 psi is fine - the caution about using more pressure is to avoid having the hose blow off from the bottle to the adapter plate and blowing pressurized brake fluid all over your shiny paint (you can't over-pressurize the brake system with the power bleeder - it's tested at the plant after bleeding at 2,000 psi).

John, whats your thoughts on my brake problem?

 

[JohnZ]

John, whats your thoughts on my brake problem?

If you have no leaks and no air in the system and the pedal goes to the floor, it's bypassing the piston seals in the master cylinder; time for a new master.

 

[Vette79]

If you have no leaks and no air in the system and the pedal goes to the floor, it's bypassing the piston seals in the master cylinder; time for a new master.

Thanks, I'm on the right track. Learning a lot about brakes.

 

[TimAT]

Sidebar-
I found out the hard way to use caution when bench bleeding a master cylinder. It's easy to "overtravel" the piston(s) in the m/c. When that happens, the seals get into an area that's not finished. Rough bore+ seals= cut seals= replace master cylinder again.