Brake valve diagnostics and restoration

[assembled]

Greetings everyone,
I would like to get some help with brake valve issue. My valve has the following symptoms:

-when LHM warms up, pedal starts pulsating
-after stopping the engine, I can hear the valve hissing
-system pressure drops quickly: pressure regulator "starts" high pressure pump every 1.5..2 s
-if I press the brake pedal really hard all the way pressure regulator only starts every 20 s

I have pulled out the valve and it does not seem to be badly worn. I will try to clean it and put back just to see what happens.

Any experience with brake valve rebuild? I keep wondering whether it is possible to restore the warn surfaces? Polishing and chrome plating to restore dimensions?

[citronut]

pulsating brake pedal is usually air in the brake circuit, it also sound like you accumulate/regulater sphere needs replacing

regards malcolm

[assembled]

Thank you for your feedback.

Regulator sphere is new. I have actually tried two good spheres and had same result. I would like to stress out the fact that when brakes are pressed all the way down, regulator kicks in only every 20 s.

What I am really interested in is how to determine brake valve condition when it is on table. Furthermore, is it possible (any experience?) to restore worn surface?

[citronut]

Thank you for your feedback.

Regulator sphere is new. I have actually tried two good spheres and had same result. I would like to stress out the fact that when brakes are pressed all the way down, regulator kicks in only every 20 s.

maybe you bleed valve ball bearing requires re/seating,
remove the 12mm bleed screw mind you dont loose the ball bearing, make sure the bearing is in the bleed port, place a copper drift of the right diameter against the ball and give it one sharp blow with a hammer,
now re/fit 12mm bleed screw,

What I am really interested in is how to determine brake valve condition when it is on table. Furthermore, is it possible (any experience?) to restore worn surface?

i think the only way to bench test them is build a test rig with a pressure gauge in circuit.

if the bore is damaged i would think the only way to recover it is to have it machined out and sleaved with a stainless steel liner,

regards malcolm

[Defender110]

It could be worth bleeding your brakes if the brake valve is still on the car. Leaking nitrogen from old spheres has been known to collect in the brake lines which normally shows itself as the rear end rising after you have applied the brake and come to a stop at traffic lights etc. The only way to get this trapped gas out of the system if it is trapped in the brake lines is to bleed the brakes. Perhaps if there is a lot of trapped gas this is preventing your pressure building correctly causing your short pump intervals and when you press the footbrake it compresses this trapped gas? Just a theory

[assembled]

Experiment worthy theory. I'll clean and reassemble the valve, put it back, bleed the system and report results.
Thank you.

[citronut]

whilst you have it apart it would pay to fit a seal kit if you can get or have one,

regards malcolm