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Leaking near master cylinder. Identify this part


Southern3.0

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1999 two wheel drive. My abs and brake warning light came on, I checked under the hood and there's an obvious leak at the master cylinder at the brake line connection. I don't know what part is between the brake line and master cylinder, does anyone know the name? I attached a picture.

 


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Cemeteryxgates

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Proportioning valve

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Southern3.0

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I don't know what that little part is called but it's not a proportioning valve. The pro valve is part of the abs valve body on the inner fender.
 

alwaysFlOoReD

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WAG; residual pressure check valve.
 

AllanD

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I will say this to all one last time before I freak out and go completely postal...

NO RBV has a "proportioning valve" unless you or someone else ADDED ONE

"proportioning" in general is accomplished by the ratio of piston area in the front brakes relative to that in the rear brakes and to a lesser degree the spring tension between the two sections of the tandem piston in the master cylinder...

This is confused further by the NON-LINEAR nature of the "servo actuated" drum drakes used on most RWD and 4X4 vehicles...


That thing pictured above is as Always floored suggests a residual pressure valve.


Another part commonly pointed to and MIS-identified as a "proportioning valve"
is a common "pressure differential switch" to detect a partial brake system "failure"
(actually "fluid loss") and ford stopped using them because they usually make a bad situation that a driver cannot help but notice worse (due to lost motion) by reducing line performance of the half of the system that was still working....

Manufacturers tend to prefer simple solutions and "proportioning valves" are complicated

My Toyota trucks had proportioning valves that varied rear brake performance by a lever that was attached to the rear axle so the more the rear suspension was compressed the more rear braking you got.... this setup was not entirely satisfactory...


Ford's "proportioning" is by design of hydraulic rations "concealed" complicated electronic systems like ABS or RABS systems.

Multi channel ABS usually works fairly well... I've personally owned FIVE vehicles with RABS and only had one of them work well enough that I didn't defeat or entirely remove the system... But if my 1994 AWD Aerostar hadn't died of other causes I'd have likely gotten around to removing the RABS system...
 
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