1968 Brake Warning Light rest problem

[TexAg]

Should have been "reset problem".

I had a leak at my distribution block, which ultimately led to a low fluid situation and subsequent Warning Light activation. I have the repair manual and have tried unsuccessfully to reset the light.

From Page 2-5 of the 1967 Mustang Shop Manual.

"Centralizing The Pressure Differential Valve

After a failure of the primary (front brake) or secondary (rear brake) system has been repaired and bled, the dual-brake warning light will usually continue to be illuminated due to the pressure diffenterial valve remaining in an off-center position.

To centralize the pressure differential valve and turn off the warning light after a repair operation, a pressure differential or unbalance condition must be created in the opposite brake system from the one that was repaired and bled last.

1. Turn the ignition switch to the ACC or ON position. Loosen the differential valve assembly brake tube nut at the outlet port on the opposite side of the brake system that was repaired and/or bled last. Depress the brake pedal slowly to build line pressure until the pressure differential valve is moved to a centralized position and the brake warning light goes out; then, immediately tighten the outlet port tube nut to the specified torque.

2. Check the fluid level in the master cylinder reservoirs and fill them to within 1/4 to 1/2 inch of the top with the specified brake fluid, if necessary.

3. Turn the ignition switch to the OFF position.

4. Before driving the vehicle, check the operation of the brakes and be sure that a firm pedal is obtained."

So, the problem is that as I carefully attempted to bleed the brakes in the opposite position, the brake warning light fluttered quickly on/off for a second, and then was on again. I'm afraid that i went too far the other direction, but I can't be sure. So now, I really don't know where the slide is, and which way to try and go. Without spending hours trying back and forth, does anyone have a secret?

Since the light never really went completely off, how do I know when enough is enough? How "slowly" do you "depress" the brake pedal?

Any help would be appreciated. I'm tempted to just unplug it and drive on.. FIDO!!:grin:

 

[rvrtrash]

It sure sounds like you went past the center in the opposite direction. I'd go ahead and loosen the opposite side, and go REAL slow on the pedal.

Steve

 

[TexAg]

Thanks, Steve! It turns out it was stuck. I had to completely disassemble.

 

[rvrtrash]

Glad you got it fixed.

Steve

 

[TexAg]

Sorry to re-open this thread, but it fits. I'm having trouble getting the line to the front driver side to stop leaking. I've pulled it apart again, and I think the threads on the reducer are damaged. Additionally, it's causing the copper crush washer to become oblong and out of shape. Does anyone know what this fitting is called, and can you get it by itself?

 

[dalorzo_f]

Do you mean the bushing? Never seen it sold separately.

On the centering issue this little tool is a handy helper to keep a switch in place while pedal bleeding.... remove switch, screw in finger tight, bleed, remove and replace switch...

http://www.npdlink.com/store/produc...ntial_valve_switch_lock_tool-178818-2981.html

 

[dalorzo_f]

This kit is all I have seen, O-rings and copper crush washer.

http://www.npdlink.com/store/products/rebuild_kit_brake_pressure_differential_valve-169774-1.html

Maybe a new crush washer will fix it.

 

[TexAg]

Thanks, I've got the centering tool, and have seen the kit. What I haven't seen is the reducer fitting. Does anyone know what the male and female sizes are? I hate to purchase an entire distribution block when all I need is the fitting. Thanks

 

[franklinair]

If you can remove the fitting, take it to an auto parts (NAPA usually carries fittings) they should be able to match the size & threads.

Neil

 

[dalorzo_f]

The crush washer should seal the large face, the flared end the other. Check the flats for scarring and the seat for the flare as well... finding a fitting with the thread x flare may be difficult.

 

[TexAg]

Thanks, dalorzo_f. There is damage to both the threads and the large face. That's why I'm looking to replace it. I just don't know what to call it, or what the sizes are. I'll try taking it to an auto parts store, but last time I looked for brake fittings, they had very little that would fit this car. Everything was metric.

 

[dalorzo_f]

Unfortunately this may be your solution:

http://www2.cougarpartscatalog.com/...Cougar-1968-1969-Ford-Mustang.html?attribs=78

Maybe WCCC can strip one of the fittings from an old trashed valve body. Drop them an email, they do a lot of OEM parts, or may be able to see if the supplier of the repro can provide just the fitting (assuming its the same imperial treads).

 

[TexAg]

Excellent idea! I called them today and they are shipping it out. Don't know why I didn't think of that. Hopefully this will fix the problem.

 

[dalorzo_f]

happy to help.... :wink: