Bubbles in Reservoir

[amdavidson]

So I pulled the brakes from my car during my suspension rebuild and the last thing left before I get it on the road is to bleed the brakes.

I used a power bleeder and also did the old pump the pedal and hold bleed. There's no bubbles at all coming out of the lines at the drums or calipers.

But I can occasionally see bubbles coming up from the bottom of the brake reservoir and if I pump with the top of the air cleaner off you can see a whisp of "smoke" coming out of the carb barrel. Is my MC leaking into the booster and misting a little brake fluid out the vacuum port when I hit the pedal?

This car was driving and braking fine when I parked it to do the suspension rehab.

I have never seen anything like this and couldnt find anything with some searching.

Please help! I want to drive my car with its new suspension!!!

[c.d.iesel]

bubbles coming up into the brake fluid res. is from

air entering the system - old rotten hose between the master and res?

a big leak somewhere in the system - and maybe fluid leaking out

somewhere also ??

smoke coming out of carb is from fuel leaking out of the float

bowl?, leaking float needle/seat?, hot? , cold ? after switching the motor off?, while idling?,

brake and carb not related - really

[2Red69s]

If the wisp of smoke is really directly related to the pumping, perhaps your "one-way" vacuum valve (between the intake manifold and the booster) is no longer only operating one way. This would diminish the "power assist" but I don't believe it would add air to the hydraulic system.

Are you talking big bubbles 1/8"+, or tiny soda-fizz bubbles, by the way?

[amdavidson]

bubbles coming up into the brake fluid res. is from

air entering the system - old rotten hose between the master and res?

a big leak somewhere in the system - and maybe fluid leaking out

somewhere also ??

smoke coming out of carb is from fuel leaking out of the float

bowl?, leaking float needle/seat?, hot? , cold ? after switching the motor off?, while idling?,

brake and carb not related - really

The hoses between the reservoir and master haven't been replaced, but they don't look like they'd be leaking. I'll try and see if I can identify any leaks from them.

I haven't seen any fluid leak out, the concrete underneath the car is clean.

[amdavidson]

If the wisp of smoke is really directly related to the pumping, perhaps your "one-way" vacuum valve (between the intake manifold and the booster) is no longer only operating one way. This would diminish the "power assist" but I don't believe it would add air to the hydraulic system.

Are you talking big bubbles 1/8"+, or tiny soda-fizz bubbles, by the way?

The smoke is absolutely related to the pressure, it occurred only when the brake was pumped and exactly when the brake was pumped. Very clearly caused by the action.

I had just idled the car, but had shut it off to deal with the braking issue... The one way could be a culprit in that issue.

The bubbles are big, 1/8 - 1/4 inch is probably a good estimate. It's not a fizz.

[amdavidson]

I re-bled the brakes today and got no further with trying to fix it.

I tried to diagnose further and locate a leak so I sprayed brake fluid around the hoses and looked for bubbles or a change in sound. No luck, but I did notice that while my assistant was pumping the pedal that there was a "hum" sound when the pedal is pumped.

A stethoscope check indicates that the hum is coming from the one-way valve to the booster as was suggested earlier. Anyone think that a vacuum leak to the booster could cause a soft pedal even when the engine is off?

How often do master cylinders go bad on these cars? I haven't read about too many failures.

Can the reservoir hoses be replaced without the MC? They seem to be plugged into the MC with a barbed fitting and I didn't see how to remove them.

[amdavidson]

I bought some parts from AutohausAZ to try and correct the issue.

New booster hose and check valve didn't do anything. So I started to replace the reservoir hoses and realized that the new grommets I bought don't fit...

Do I have a non-oem master cylinder?

The only markings I can find on it is this:

The old grommets can't be put in because they disintegrated upon removal. How do I get some that'll fit this MC?

Thanks in advance.