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Bleeding with no result.

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Tullamore

Tullamore

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I just picked up a TR6 and am trying to sort out the brakes. There is no pressure on the pedal at all.

I can bleed the rear brakes just fine but when I move to the front nothing come out (im using a vacuum bleeder). The fluid in the MC doesn't come down any.

Does this mean my MC needs a rebuild or do I need to prime it somehow? It was empty when I got the car.
 
Disconnect the front brake lines at the wheel cylinders, if nothing comes out when you press the brake pedal that would indicate a problem in the master cylinder or the Differential Pressure switch.
 
That switch is actually a "Pressure Differential Warning Actuator", aka PDWA. It does not change the pressure from front to rear. It warns of a sudden change in pressure. The electrical connector on the switch goes to the brake warning light on the dash. There is a piston inside that when the pressure drops on one side it moves the piston and closes the electrical circuit. If it is a later model you can rebuild this switch by disassembling, cleaning and renewing the o-rings. If it is an early style with cup seals your out of luck. However, even if this piston slides it should not block the flow, just reduce it.

As stated before, you could have clogged brake lines. Especially the flexible lines as they can collapse internally and look okay externally. You could also have corrosion in the calipers themselves. Un-hook the brake lines from the caliper and work backwards torwards the Master cylinder until you find the problem.

Good Luck

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If the MC was dry you may need to bleed it there first. Close off the wheel bleeders, then use your line wrench to crack the lines as they go into the MC, while you stroke the pedal a few times (may need a helper). Use a rag around the line to absorb any fluid, and throw it away afterwards(brake fluid strips paint as I imagine you know). Keep enough fluid in the reservoir of course while you do it to keep that from going dry. It should be fairly obvious when you're getting fluid pumping, versus air. This method has worked for me anyway. Sort of 'bench bleeding' the MC while it is in the car. Good luck... Pete
 
I like your idea of using the vacuum bleeder. If you take a full stroke on the pedal with an old master cylinder the rubber cups will get mangled on all the rust and mung that builds up at the end of the cylinder. Half strokes only. I messed up a couple of times on my cars before I figured out what was happening. Do the bleeding at the master like someone else suggested and then keep working toward the wheel, you'll find it. Ken
 
Well its not the MC, I got shot with brake fluid when I undid the pipe on the dist. block on the frame. I think whoever suggested the hoses have collapsed inside may be right so I am ordering SS braided lines anyway.
 
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