| proportion valve [message #101113] |
Mon, 27 September 2010 08:26  |
Brian Leith
Messages: 22
Registered: February 2004
Location: St Louis
Karma: 0
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Junior Member |
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I recently had a rear brake line blow out the brake light came on and it isolated the brakes to the front. I have replaced the rear lines and bled them, however I am getting no power to the rear brakes and the brake light will not go off. Is there some kind of way to reset that proportioning valve?
1975 Elle II
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| Re: [GMCnet] proportion valve [message #101114 is a reply to message #101113] |
Mon, 27 September 2010 09:04  |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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Brian, it sounds like the spool valve inside the (proportioning) valve was
forced out of the center position by the loss of pressure on one side and
the higher pressure on the opposite side. If there is any foreign material
present in the valve assembly and the spool moves over into it, it will jam
the spool causing the problem you describe. How did you bleed the brakes,
with a pressure bleeder from the MC, pumping the MC, or a vacuum source on
the wheel cylinders? First of all try a power bleeder as that uses equal
pressure on both sides of the valve assembly, and if the spool is not stuck
too tightly, could center the spool again. Otherwise, removal of the
fittings from the MC, which is always difficult, and higher pressure air
applied to the inlet may dislodge the spool. If this doesn't work, then bite
the bullet and replace the whole assembly. Don't take chances if you are
unsure, brakes are nothing to to have in poor operating condition.
Jim Hupy
Salem, Or
78 Royale, 403
On Mon, Sep 27, 2010 at 6:26 AM, Brian Leith <beebad3@hotmail.com> wrote:
>
>
> I recently had a rear brake line blow out the brake light came on and it
> isolated the brakes to the front. I have replaced the rear lines and bled
> them, however I am getting no power to the rear brakes and the brake light
> will not go off. Is there some kind of way to reset that proportioning
> valve?
> --
> 1975 Elle II
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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