I can now emphasize with all the people that have had brake problems and my answer was " there is air in the lines, and you need to do is bleed the brakes."

I started at 8am this morning, and I stopped at 5pm. Enough bleeding to get all the air out, and the brakes still dont work. Today I replaced my master cylinder with a new one at 1pm, and then 4 more hours of bleeding and the pedal still goes to the floor, as in, no brakes at all.

Tomorrow I will order a new power booster.

This is now getting FRUSTRATING!!.

kdf

 

did you check the calipers? they leaked inside the caliper on mine and i couldn't tell what the problem was until i took them apart. my pedal also went to the floor. i changed all four and new pads and they are as good as new

 

Have you tried a pressure bleeder? I had no luck bleeding them manually but the pressure bleeder did the trick. Some on here have had success gravity bleeding. Just fill up the resevoir and open the bleeder valves a bit and let them drip for a while.

 

 

kdf. When you depress the brake pedal with the top off of master cylinder do you see any movement in the fluid? On mine there is a small jet of fluid up out of the refill hole. If you press hard it will jump up out of the MC so be careful and do not get brake fluid on any painted surfaces. Dot 3 fluid is an excellent paint remover. This is caused by the MC seal pushing fluid and almost instantly closing off the refill hole. When the refill hole is closed by the seal then the brakes begin to be applied. With everything closed up can you turn one of the rotors while a helper presses the pedal? If you open one of the bleeder screws and then press the pedal does fluid squirt out of the bleeder? Answer these ?s and we will move on from there. I gravity bleed mine with the car level. mike...

 

I have rebuilt the calipers with new seals. That is what started this process in the first place. I took them apart, cleaned and honed the sleeves, and put in all new seals. I also have new pads. The car is up in the air so I havent driven it yet. That rules out rotor runout also.

kdf

 

I have a Motive Pressure bleeder. It worked great. I could keep a constant pressure and had good luck getting all the air bubbles out. That is what the frustrating part was, after a long time of bleeding, getting all the air out of the 4 calipers, then finding I still have no brake resistance. That is when I replaced the master cylinder with a new unit.

kdf

 

Hello Mike,
I cut and pasted all your questions below.

1. When you depress the brake pedal with the top off of master cylinder do you see any movement in the fluid?
Yes I see fluid movement out of the front and back sections. The fluid will almost shoot out of the master cylinder if I push the pedal hard enough. Also there is movement when I let off of the brake pedal.

2. With everything closed up can you turn one of the rotors while a helper presses the pedal?
I have not tried that yet. Let me see if I can get someone to volunteer to help check this on Sunday.

3. If you open one of the bleeder screws and then press the pedal does fluid squirt out of the bleeder?
I would say yes. I used the Motive Pressure Bleeder and there was definately fluid squirting out of all 4 calipers. Also when I did the gravity bleed I had almost 1 full water bottle full per caliper, so I know there is fluid movement.

Answer these ?s and we will move on from there. I gravity bleed mine with the car level. mike...

I hope to get the rotor question answered on Sunday.

kdf

 

OK. Are you bleeding the calipers using only the top bleeder screws on the rear? There should be a bleeder on both halves of rear calipers on top. On the bottom outside there should be a plug. On the front the bleeder should be on top. mike...

 

check your rubber brake hoses. Are they old ? Sometimes old hoses will swell when you hit the pedal and you will never get a hard pedal. Easy to check.

 

It sounds like you are pretty savvy and know what you are doing. I just replaced my master on my '79. I had to bench bleed the thing for an eternity to get all the air out of the bores before I put it on the car. I was surprised at how long it took and glad I did it.
If you rushed and put the MC on the car and started the bleed process, you may have a long way to go before bleeding works.
Also, my "complete" master did not include the seal at the back of the unit where it mates to the booster. For the '78 and up model, that seal and its retainer are discontinued. So, I bought thick gasket material and cut a new one myself to ensure good seal and proper adjustment of the MC relative to the push rod.
I may be wrong, but a bad booster shouldn't keep you from having pedal pressure as it is not connected with the hydraulic system. It would certainly increase pedal effort if it were inop, but it wouldn't create the symptoms you are having. I think. Maybe someone else will weigh in if I am wrong.

 

The master MUST be free of air,this is where most guys fail.
Also , tap tap tap all fittings (and common sense places where air can be trapped) while your bleeders are open. Air can hide even with the Motive.

 

Pinch off a rubber brake line, one at a time, to see if you get good pedal. If you do, then you have isolated which wheel is giving problems.

 

I got in a hurry one time and was blind to the second bleeders on the rear....NO PEDAL at all....then I remembered....THE OTHER BLEEDERS ! (LOL !!) After I bled them, AWESOME pedal...

Could have kicked myself because I knew better...

And I use the Motive preasure bleeder....great tool.

 

Make sure your not leaking at any of the connecting points. not easy to see but it can be that Pinta your looking for. Make sure hoses going into calipers are tightwith brass washer, many times people think there tight but not. If you change hoses make sure connection from line to hose is also tight.

Just a thought to add to the other good info you have received.

 

Did you bleed the new master cylinder?

 

Also if it is power brakes make sure your check valve is working correctly for the brake booster. If the engine is running and the brakes are going to the floor it could be lack of vacum in brake booster.

 

 

Hello
I replaced the rubber brake lines with the braided steel ones. I have another thread in the technical foruum on the complete rebuild of the calipers and what has been done.

kdf

 

Thanks for all the comments and checks each of you have provided.

I have photos of the original problem in the technical forum, and this thread was to vent my frustration, but I am getting good tips, suggestions and checks on what has been done.

The original symptom was VERY soft/spongey feeling brakes and the pedal would go to the floor to stop. Driving the car you would wonder if it was going to stop. What I found was a leaking caliper, brake fluid infused brake pad, two front brake pads were broken at the end, and contaminated brake fluid. That is where the starting point was.

So far I have done the following.
1. Started by bench bleeding the original master cylinder- no improvement.
2. Replaced the brake booster check valve- no improvement
3. Checked for vacuum to the brake booster- I forget the numbers but it was in spec for the values I wrote on my check list. Maybe around 15 inches so it is good.
4. Rebuild the calipers with new seals. The calipers were already stainless steel sleeved.
5. Install braided steel brake lines.
6. Put the copper washers on the front lines only. I dont think the rear ones had the same bolt/washer assembly to fit at the hardline connections.
7. Flushed the lines with brake fluid until new DOT 3 fluid was coming out.
8. Motive pressure bleed the system. Lots of air coming out. Good fluid comes out when opening and closing the bleeder screws.
9. Rear brake calipers have 2 bleeder screws at the top of the caliper. One on the inside, one on the outside. The 3rd hole location at the bottom of the outside caliper is a bolt.
10. Tapped the calipers during gravity bleeding with a rubber mallet. This was a good suggestion as it did get some more air bubbles out.

Recheck- still no pressure with everything sealed, tightened and checked. The brake pedal goes straight to the floor with little to no resistance.

11. Decided to replace the master cylinder anyway. Bought a new unit, with the deep bore to match the brake booster pushrod. Bench bleed new unit, and putting the master cylinder at a angle to get the holes better alinged vertically. This was from a previous thread in which the forum poster showed the master cylinder and how the holes are slightly offset. Bled good with no air bubbles present.
12. Gravity bleed for 3 more hours. Always checking the master cylinder to make sure it was not empty.
13. Tighten everything up, start the car to get good vacuum to the booster...no brake pressure. Pedal goes straight to the floor.

14. Went inside to order a brake booster. It arrives today- Sunday for replacing.

And thats where I am with the brakes to date.

Thanks to all for the suggestions. They help me in checking that I did not miss something.

kdf