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#1 |
Registered User
Join Date: Jun 2010
Location: San Diego Co.
Posts: 1,162
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Combination valve malfunction??
I've done a search, and found some good info, but none of the scenarios were exactly the same as mine, so here goes.
'72 C10 disk/drum. Just finished a complete brake system overhaul. The only part between the pedal pushrod and the pads that isn't new/rebuilt is the combination valve....but it is new to this truck. I sent the calipers, master cylinder, combination valve, and vacuum booster out to be overhauled. The shop said that my combination valve was shot, but they had one just like it and gave it to me for the price of overhaul. The pin on the metering portion was in, and they said it would pop out after the bleeding process. Well, the bleeding took a while, but we have a firm pedal. Hooked up the wire to the warning switch and had the red brake light on. Pushed hard on the pedal, and the light went out. But here's the thing, the pin on the metering valve has never popped out. It was clamped during bleeding as the procedure calls for. I do have brakes, but they feel about the same as they did before all this work! ![]() I have the factory service manual and have read all about this valve. I'm thinking this "replacement" valve I got might not be any better than my original, which they said was junk. The truck just doesn't stop as well as I think it should, and even though my brake (idiot) light is extinguished, that pin on the metering valve has never popped out. So what do y'all think? I appreciate all your input. |
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#2 |
Registered User
![]() Join Date: May 2012
Location: Anton, Texas
Posts: 2,364
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Re: Combination valve malfunction??
slikside: if you have good brakes just drive it a while and get ever thing seated in, if the peddle is real hard check the vacuum to the booster and make sure its getting full vacuum and hooked up properly ....
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#3 |
Registered User
Join Date: Mar 2004
Location: CA
Posts: 2,057
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Re: Combination valve malfunction??
I've had the prop valves go bad on me, I'd get a different one and try it. Or, do as ole dollor said and make sure the pads and shoes are seated all the way.
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#4 | ||
Registered User
Join Date: Jun 2010
Location: San Diego Co.
Posts: 1,162
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Re: Combination valve malfunction??
Quote:
Quote:
And I'm still open to any and all opinions....please. |
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#5 |
Registered User
![]() Join Date: May 2012
Location: Anton, Texas
Posts: 2,364
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Re: Combination valve malfunction??
seated in means that the brake shoes lining wear to match the drum all the way around ...a long time ago we had a machine that ground off the extra lining of the shoe so it would be the same all around and seat in faster...took all the high sides off the shoe....you would match the shoes to the drum...like you said the lining on the shoe was just touching in a few spots....hope this helps.
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#6 | |
Registered User
Join Date: Jun 2010
Location: San Diego Co.
Posts: 1,162
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Re: Combination valve malfunction??
Quote:
Ok, ole dollar, I've got it now. What I'm seeing now is the beginning of that seating process....the wearing in of the shoes to fit the drums. And, when fully seated, those brakes will be even more effective....right? I'm guessing that this is a non issue with front pads due to how the caliper is mounted and pad to disk angle?? |
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#7 |
Registered User
Join Date: Jun 2010
Location: San Diego Co.
Posts: 1,162
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Re: Combination valve malfunction??
Also just got off the phone with the outfit that rebuilt/supplied the new/old combination valve.....they said that not all pins will pop out, and that as long as it isn't leaking, there really isn't any concern. Since I was able to equalize the pressure between the front and rear brakes (as evidenced by brake warning idiot light going out), I am inclined to believe them. In my search before starting this thread, I found a case where the pin would not pop out, AND he was UNABLE to get his brake warning light to extinguish. That guy eventually got a new valve, and that solved his braking issues.
So I think I'm just going to go with this for a while, and keep an eye on that valve. The shop provided a 6 month, unlimited milage warrantee on parts that they rebuild, so if it starts leaking anytime before that (or after) then I know I need to replace it. |
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#8 |
Registered User
![]() Join Date: May 2012
Location: Anton, Texas
Posts: 2,364
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Re: Combination valve malfunction??
good news...now you can take it out and have some fun....but not to fast for awhile....let the shoes seat in good.....
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#9 |
Registered User
Join Date: Jun 2010
Location: San Diego Co.
Posts: 1,162
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Re: Combination valve malfunction??
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