<div dir="ltr">Blowing/sucking into the hose from the intake to the booster will verify if the one way valve is functioning. That it is all it will tell you. The described condition is not consistent with a failed one way valve. <div>A leaky master can leak fluid into the booster. and eventually if the amount of fluid builds up enough it will get sucked into the engine and burned.*. Quite often when the master is leaking like this you can see a trail of brake fluid and dust on the face of the booster directly below the master cylinder itself. </div><div>the other common source for mystery brake fluid disappearances is the rear wheel cylinders. Between where they are located on the backing plate, and the dust in the rear brakes it can take a fair amount of leakage before any is visible. I would suggest if the booster is dry, you pull the rear drums and examine the wheel cylinders. If there is no obvious leaks, be sure to peel the boots back and check inside.</div><div><br></div><div><div>hope this helps</div><div>Rick</div></div><div><br></div><div>* I had a friend that had a Series 1 E Type. One day he comes out for a drive and checking under the hood he sees the brake fluid is low. He grabs a can and starts pouring. All of a sudden the car is billowing acrid white smoke AND the master reservoir is not getting full. After a couple of second of Whaaaaaa? He realized that the master had failed and the booster was full to the vacuum hose port, so everything he poured in was going right out the exhaust. </div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, May 6, 2020 at 12:49 AM PaulHunt73 via Mgs <<a href="mailto:mgs@autox.team.net">mgs@autox.team.net</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><u></u>
<div bgcolor="#ffffff">
<div><font size="2">I'm not aware that blowing and sucking on any tube at the carb
will help in diagnosing the brakes. If you mean the servo hose that should
come from the inlet manifold but still be no help.</font></div>
<div><font size="2"></font> </div>
<div><font size="2">Stomping on the pedal should not put air into the system, if
it does then there is a fault somewhere that needs to be found.</font></div>
<div><font size="2"></font> </div>
<div><font size="2">Is this single-circuit or dual-circuit brakes? The
former should have a 'slow-return' valve in the master outlet</font> <font size="2">and with that if a couple of quick pumps on the pedal makes the pedal
shorter and harder, but then it goes long and spongy again if released for a few
seconds, that does indicate air in the system. Dual circuit
varied.</font></div>
<div><font size="2"></font> </div>
<div><font size="2">Unless the fluid level in the master dropped right down
to outlet level, or you have opened the plumbing anywhere, you should not get
air in the system by being parked up. A leak will of course lower the
level, could possibly allow air in I suppose, but doubtful in my mind.
I've found that fluid dropping on a concrete floor 'evaporates' over time.
Check the carpets under the pedal as that is another place where fluid goes if
the master secondary seal fails.</font></div>
<div><font size="2"></font> </div>
<div><font size="2">Bleeding method varies according to system type i.e. single or
dual.</font></div>
<div><font size="2"></font> </div>
<div><font size="2">PaulH.</font></div>
<blockquote style="border-left:2px solid rgb(0,0,0);padding-left:5px;padding-right:0px;margin-left:5px;margin-right:0px">
<div style="font:10pt arial">----- Original Message ----- </div><font size="-1"><font face="Arial"><br>I have a power assist brake system which after
bringing out of winter cover my MGB GT V8 exhibited brake failure No
brake fluid on the floor but it did need topping up. So added Dot
4 but still soft squashy pedal. Blowing/sucking on
tube to Edelbrock carb (I have a Rover V8 dropped in) it sucked but would not
blow (I understand this is correct}. So we figured that the brakes need
bleeding - is this a correct diagnosis? Any tips for a non-brake but
fairly well versed owner. If I stomped a lot on the pedal when
engine running would that put air into the brake
pipes<br></font></font></blockquote></div>
_______________________________________________<br>
<br>
<a href="mailto:Mgs@autox.team.net" target="_blank">Mgs@autox.team.net</a><br>
Donate: <a href="http://www.team.net/donate.html" rel="noreferrer" target="_blank">http://www.team.net/donate.html</a><br>
Suggested annual donation $12.75<br>
<br>
Archive: <a href="http://www.team.net/pipermail/mgs" rel="noreferrer" target="_blank">http://www.team.net/pipermail/mgs</a> <a href="http://autox.team.net/archive" rel="noreferrer" target="_blank">http://autox.team.net/archive</a><br>
<br>
Unsubscribe: <a href="http://autox.team.net/mailman/options/mgs/richard.ewald@gmail.com" rel="noreferrer" target="_blank">http://autox.team.net/mailman/options/mgs/richard.ewald@gmail.com</a><br>
</blockquote></div>