Is this possible?

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Swinger4me

Swinger4me

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This could save me a lot of money if this could be possible. My '73 Swinger is factory equipped with power front disc/ rear drum brakes. The master cylinder needs to be refilled about every 100 miles of city driving. There is no fluid leaking by the wheels or anywhere else so I'm assuming my MC is leaking back into the booster.
My 360 crate motor has 1000 miles on it. Under hard acceleration, I get blue smoke out the exhaust but I never have to add engine oil.
Here's my question: Is it possible that the vacuum assist line is sucking brake fluid out of the booster and into the intake system?

The car is in cold storage at the moment. This will be the first thing I look at when/if it ever gets warm out.
 
No. Brake fluid is flowing downward in liquid form. For it to get in that vacuum line it would need to be atomized and inside a ruptured booster diaphragm.
 
yes it will, it happened on my 73 duster ,look at the line going to the port on the intake manifold the 2 cylinders on that vacuum fitting the spark plugs will show darker then the others also that is how a a/c vacuum pump removes oil/moisture after the freon is out of the system .
 
A ruptured vacuum booster equals poor operation of the booster, and poor engine operation due to improper fuel air mixture.
I have seen GMs trans modulator valve send trans fuel into the intake.
I haven't seen owners drive a vehicle very long with any of these faults.
If they did, these fluids would destroy the tubing.
 
Take a real good look underneath where the master and booster come together, as most of the time when there is fluid loss and you don't see any leaks at the wheels, this is where it is going.
Is it wet? or have evidence of being wet?

And I have seen brake fluid getting pulled through a booster before also.
It may not affect the brakes though, due to the fluid swelling the rubber diaphram but still sucking fluid through it at higer R's.


RedFish said:
A ruptured vacuum booster equals poor operation of the booster, and poor engine operation due to improper fuel air mixture.
I have seen GMs trans modulator valve send trans fuel into the intake.
I haven't seen owners drive a vehicle very long with any of these faults.
If they did, these fluids would destroy the tubing.
Click to expand...

My brother bought a Ford truck with a C6 in it, and called me saying that the engine and trans were both junk because the engine smoked real bad and it wouldn't shift out of first.
I told him to pull the vacuum modulator line, and sure enough there was trans fluid running out of it.
A 6 buck modulator fixed both problems.
 
The fluid would need to be blowing by the seals on the piston in the MC in order for it to enter the booster. You would notice this by the pedal slowly creeping to the floor after you pumped it up.
 
Leadfoot said:
The fluid would need to be blowing by the seals on the piston in the MC in order for it to enter the booster. You would notice this by the pedal slowly creeping to the floor after you pumped it up.
Click to expand...

Not neccesarily.
The rear seal would be leaking but the front seal could be holding pressure.
Also, it might only leak when sitting and the cup seal isn't expanded.
(this is really common for old rubber parts)
 
TrailBeast said:
Not neccesarily.
The rear seal would be leaking but the front seal could be holding pressure.
Also, it might only leak when sitting and the cup seal isn't expanded.
(this is really common for old rubber parts)
Click to expand...

Just encountered that on my '73 Duster.

Perfect brakes, but it would leak fluid from the seal when the car was parked. Only it was easier to track down on my car, cause I have manual brakes... Wet carpet that smells like brake fluid, yep, bad master cylinder :D Bolted on a new Master Cylinder and all is good again.

I've seen a lot of vehicles where fluid was being sucked through the booster into the intake and the brakes were otherwise ok.
 
Pull the vacuum hose off at the booster,, and stick a longish square screwdriver down the hose, scrape the inside walls with the driver,, pull it out,, if its leaking,, you should see residue on the s/driver..

hope it helps
 
74Dusted said:
Just encountered that on my '73 Duster.

Perfect brakes, but it would leak fluid from the seal when the car was parked. Only it was easier to track down on my car, cause I have manual brakes... Wet carpet that smells like brake fluid, yep, bad master cylinder :D Bolted on a new Master Cylinder and all is good again.

I've seen a lot of vehicles where fluid was being sucked through the booster into the intake and the brakes were otherwise ok.
Click to expand...

Yep, that's a clue alright, when your carpet is soaked. :)



inertia said:
Pull the vacuum hose off at the booster,, and stick a longish square screwdriver down the hose, scrape the inside walls with the driver,, pull it out,, if its leaking,, you should see residue on the s/driver..

hope it helps
Click to expand...

GOOD CALL, for some stupid reason I didn't think of that.

DUH
 
Of course this can happed. A brake booster does not just "rupture." It can leak "slightly" think of it as an orifice, a pinhole. Around the seal, with the engine running, this would easily cause brake fluid to atomize.

As someone above said, you should see evidence in "the path" from the check valve, hose, fitting, etc.

And, really, use your head. There is no real alternative explanation
 
Since the car is a '73 you really should replace the master cylinder anyway just for preventive maintenance. It'll probably solve your problem & you'd be done with it.
 
cudajim said:
Since the car is a '73 you really should replace the master cylinder anyway just for preventive maintenance. It'll probably solve your problem & you'd be done with it.
Click to expand...

Especially since they are so cheap and available.
 
Why not lets argue about the sky being blue?
 
Ok, thank you all for your input.
The carpet is dry, the outside of the MC is dry and the pedal does creep down when pressure is held on.
It appears to be the original MC/booster (part of the MOPAR decal is still there) I will be replacing the whole unit.
If/when this does the trick, it'll be much cheaper than the ring job I was told it needed.
I'll be sure to keep you all posted on the results.

________________________________________________________________________
Now all we need is some GLOBAL WARMING! Would somebody PLEASE call Canadia and tell them they can have their F@%#ING AIR BACK!
 
Your problem doesn't stop there,, the boosters leaking too,, that why it's sucking from the M/C..

IIRC brake fluid burns white,, sorry

hope it helps
 
The brake fluid will destroy the booster if you let it continue to leak into the booster.
 
You should be able to pull the vacuum hose off the intake that goes to the booster and see/smell brake fluid if it is going thru the engine. This how I use to verify ruptured Transmission modulators.
 
SGBARRACUDA said:
You should be able to pull the vacuum hose off the intake that goes to the booster and see/smell brake fluid if it is going thru the engine. This how I use to verify ruptured Transmission modulators.
Click to expand...

Thanks Roy, we kinda covered that.
I even said "DUH" :D
 
RustyRatRod said:
Why not lets argue about the sky being blue?
Click to expand...

I dont argue anything. Murphys Law, Anything that can happen, will.
I know I aint seen it all. I certainly haven't seen brake fluid travel to the intake, but I can now say I've heard tale of it happen.
 
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