1978 FJ40, Original MC (MasterCylinder) rebuilt in 2013 and again now.
Removed and cleaned the PV (ProportioningValve) by removing and inspecting the 21mm nut, spring, rubber washer, and confirmed fluid flow. (Seems good??)
Bare with me as I attempt to explain:
Was driving and discovered the Brakes were not releasing when I left off the pedal.
*Solution: Release the bleeder screw and get back home. (without braking unless I had to)
Figured it was the rear drums and rebuilt the cylinders and reassembled. Test drive - fail.
*Assumption: Soft lines are bad/collapsed (replaced these in 2014 with ClassicTube soft lines)
Here is where I am now:
While replacing soft lines I realized there was very little fluid in the lines. Naturally assumed the MC was bad and rebuilt it.
While bench bleeding the MC seemed to work correctly, but still no fluid would bleed into the lines. I Removed the PV and cleaned it well replaced. Confirmed I had open hard line from the PV all the way to the Rear Frame Rail where it attaches at the soft line- It is open and clear.
After much struggle I removed the MC & PV again... and proceeded to bench bleed the MC, then attached the PV (on the bench) and Also bled that too; and it seems to work from MC to and through PV on the bench.
When I install it on the truck, I attached the front and rear hard lines to the MC and left open the outbound side of the PV to visually inspect the gravity feed of fluid through the system and it is minimal at best. Note: When I press the pedal it 'spits' some fluid from PV, but in my logic I would assume fluid would flow freely from MC and out the PV... That is not happening.
I attached the hardline to the outbound side of the PV and went under the truck, just in front of the rear axle just before the soft line and used a HOLT [pneumatic brake bleeder @ 90psi] and I get very little fluid flow to that point.
Again: MC is behaving normally; And PV seems to behave normally on the bench.
I do believe my understanding - lack of understanding - of the Proportioning valve is my issue?
IS the Proportioning Valve Bad?
How do I confirm that the PV is bad or is it still good?
How should it behave when off the truck or not in a closed hydraulic system vs a closed system.?
When I move it to the truck I am getting good throw with the pedal. (bench bleed set up) but when I put the hard lines on it seems the system fails.
What next???
And any expectations as I go back through it step by step....
Thank You in advance.
Removed and cleaned the PV (ProportioningValve) by removing and inspecting the 21mm nut, spring, rubber washer, and confirmed fluid flow. (Seems good??)
Bare with me as I attempt to explain:
Was driving and discovered the Brakes were not releasing when I left off the pedal.
*Solution: Release the bleeder screw and get back home. (without braking unless I had to)
Figured it was the rear drums and rebuilt the cylinders and reassembled. Test drive - fail.
*Assumption: Soft lines are bad/collapsed (replaced these in 2014 with ClassicTube soft lines)
Here is where I am now:
While replacing soft lines I realized there was very little fluid in the lines. Naturally assumed the MC was bad and rebuilt it.
While bench bleeding the MC seemed to work correctly, but still no fluid would bleed into the lines. I Removed the PV and cleaned it well replaced. Confirmed I had open hard line from the PV all the way to the Rear Frame Rail where it attaches at the soft line- It is open and clear.
After much struggle I removed the MC & PV again... and proceeded to bench bleed the MC, then attached the PV (on the bench) and Also bled that too; and it seems to work from MC to and through PV on the bench.
When I install it on the truck, I attached the front and rear hard lines to the MC and left open the outbound side of the PV to visually inspect the gravity feed of fluid through the system and it is minimal at best. Note: When I press the pedal it 'spits' some fluid from PV, but in my logic I would assume fluid would flow freely from MC and out the PV... That is not happening.
I attached the hardline to the outbound side of the PV and went under the truck, just in front of the rear axle just before the soft line and used a HOLT [pneumatic brake bleeder @ 90psi] and I get very little fluid flow to that point.
Again: MC is behaving normally; And PV seems to behave normally on the bench.
I do believe my understanding - lack of understanding - of the Proportioning valve is my issue?
IS the Proportioning Valve Bad?
How do I confirm that the PV is bad or is it still good?
How should it behave when off the truck or not in a closed hydraulic system vs a closed system.?
When I move it to the truck I am getting good throw with the pedal. (bench bleed set up) but when I put the hard lines on it seems the system fails.
What next???
And any expectations as I go back through it step by step....
Thank You in advance.