jcddyy

Happy Holidays Olds fans. About a month ago I noticed a small leak bw the MC and power booster. I began to lose pressure but as I pumped brakes the pressure began to build back up. I have the service manual and from trouble shooting I first manually bled the brakes which helped some but the leak between the booster and MC was worse. Today I installed the MC as the service manual stated. I have bled the brakes over and over again. I still have no brake pressure. Can somebody help me please. I have scrolled thru many threads and it looks like im missing something. Is bench bleeding the process of bleding the MC before install? I didnt do this. I own a 72 cutlass with drums all the way around. Maybe soon I can upgrade to a Disc conversion. Hope santa is an ClassicOlds member.

jcddyy

I will in the morning. Is it as simple as attaching plastic tubes with plugs and impacting the piston part that contacts the booster? any tips?
thanks for reply

MDchanic

You've answered your own question.

The M/C must be level when bench bleeding, which is why you can't do it on the car, where it is mounted at an angle.

- Eric

MDchanic

There are instructions with the new M/C.
Install the plugs they gave you and follow their instructions.
Basically, you clamp the M/C in a vise and push the piston in all the way, over and over, until the bubbles stop.

If you don't have a steady vise available, you can press the piston with a hammer handle while holding the M/C against a tree or a sturdy wall.

- Eric

jcddyy

I just wasnt entirely sure. I do appreciate the help. Thanks

jcddyy

Cool . Now I just need to find the box! Will the piston push out on its own once it is pushed in?

I dont have a vise but I do have walls and trees. Thanks again. Im a better learner when Im hands on honestly.

MDchanic

He doesn't have a vise.

Oh yeah. It's got a STRONG spring, which is why you need a vise or a tree.
Without a vise, you'll have to prop the M/C against a sturdy object, hold the hammer handle or whatever you use with both hands, and lean your body into the M/C to depress the piston, because you want to keep the force line straight into the M/C, and not off at an angle. That's why a vise is easier.

- Eric

jcddyy

I got it. Now was there any harm done installing the master without bench bleeding?

jcddyy

Thanks . Safety first always. I did get brake fliud on the last paint job and learned the hard way.

Lady72nRob71

Yep, it must be bench bled. I doubt you did any harm to the MC. Just remove it again and bench bleed it.
See how I did it without a vice here:
https://classicoldsmobile.com/forums...tml#post331973
I also had some helpful tips in there, too.

Do not fill more than 3/4 full to avoid spillage when installing it on the car.

lshlsh2

I used part of a 7/8 inch wood dowel to bench bleed mine.

Larry

jcddyy

I see. I used your idea an set up a board to bench bleed the MC. I found the plastic tubes and followed the directions and also read your thread . I did exactly as instructed. I must have pushed the piston in a few hundred times over an hour and a half time frame. I installed the MC just as you did in the thread and used the "two man" bleed method. I went around the rotation three times and still no brake pressure. The fluid coming out of the wheel cylinders are clean and the flow is responsive to the petal. I inspected the brake lines and looked for leaks again. I didnt find any leaks. I finially just took the MC off and returned it to bloody Autozone. It was a reman and went to a local guy down the street who had a new Dorman for 35$. Im still stuck and can hope it was just the POS i bought at AutoCrap.

Lady72nRob71

Did you redo the rest of the brakes or have the shoes off? If so, you MUST adjust the shoes to be close to the drums. If they are not, then you will use up all your pedal travel moving the shoes...

Only other issue would be a bad master if you bled it right (sounds lke you did)...

jcddyy

No I didnt. I put new shoes and cylinders a month ago.

I bench bled the new MC(not a reman) and installed. Bled the system again and still no pressure. I called a couple of shops and spoke with mechanics there. When im bleeding the brakes the car is off and I get real good pressure while im bleeding. When I turn the car on brake petal hits the floor. The mechanic said its my booster. I went and bought a new one installed .

Do I have to bench bleed th MC again or can I just bolt on the MC and bleed the system?

MDchanic

If the M/C has not been run dry, you do not have to bench bleed it again.

- Eric

Lady72nRob71

With as long as it can take to get a booster off, it might run dry just by seepage around the port plugs...

jcddyy

I better bleed it again thanks for the help. Hopefully it doesnt rain here in Dallas tomorrow

jcddyy

I guess I can check for bubbles before I slap it back on.. Thanks Eric

Lady72nRob71

Yea, just put the bench bleeder kit back on it as best you can and hopefully it will not leak more. Do another quick bench bleed before reassy.

You can have your brake booster rebuilt if you want to stay original and can let the car be idle a few weeks. Not too much more than a "might fit" chinesium replacement.

Supposed to rain Sat and Sun, at least so they say...

jcddyy

A week later and 3gallons of fluid later I finally have decent pressure. The petal still feels a bit spongy but its gonna have to do. Thanks for all the advice. Now that it has been sitting for the majority of two weeks the "Gen" light is on. Who would have thought .. Here we go. I believe this to be a result of it sitting fot a while. Im hope it just needs a battery charge

Lady72nRob71

Well glad you finally got it bled. This is a job I really hate and you know why!

Charge the battery overnight on less than 2A.
The GEN light on is not from sitting - something else is wrong.
With engine running, measure voltage across your battery - should be 13V to 15V. Lower means either ALT or regulator are not working.
Check connections to both, first.

jcddyy

Thanks alot. Yup I have drums all the way around and gonna start saving some funds for a conversion next time.

As far as the gen light I charged battery and stzrted right up.. Gen light stayed on . It seems to be dying at idle when brakes applied. Im running a external volt regulator and not sure how to troubleshoot if the regulator or alt is bad. Any advice.. My guess is alt.

Lady72nRob71

What is your voltage reading at idle?

jcddyy

Not sure.. Im working now and no meter handy. I pulled in to work at 7a and as soon as I pulled in she died.. I could tell at every stop she wanted to die si I put it in neutral and kept it alive at stops.. Ill check once I get a boost and home. Should be 13 area?

Lady72nRob71

Yes, 13-15V at idle.
Check for disconnected or cracked vac hoses, esp. the one for the brake booster.

If you are driving withthe GEN light on, you may be running off just the battery. If so, it might be getting weak enough to not run the ignition system correctly. I would not drive anywhere until you get it fixed.

jcddyy

Im sure its close to it. I have to get home atleast. Whats worse case? Lose power on the highway? Thats bad news..

So how do I narrow down alt or regulator problem? Alt is suppose to keep charge correct? I can take it to auto parts house and test but what if regulator is fried will it burn up alt ?

Vac hoses are brand new from booster.

Lady72nRob71

A parts store can check the alt. If bad, you might open it up to see if just the brushes are worn down. If so, you can replace them for just a few dollars.

If you still have the old original style mechanical regulator, you might just get an electronic replacement - should be under 20 bucks. Check Napa. If that is not the problem, you can always keep it as a spare.

Check your wiring first - look for burned or poor connections at the terminals..

J-(Chicago)

I can send you another alternator if you want to try it. My cars all use 80's alternators, and I have no use for the older style.
Better to spend 10 bucks on shipping, than 50 bucks for a new one.
You could rebuild your original one while the other is in place, or use mine for the core exchange as well.
That's the only reason I keep it around.
Just a thought.