Author Topic: Which brake booster?  (Read 11104 times)

Online bd

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Re: Which brake booster?
« Reply #15 on: August 03, 2015, 09:43:23 PM »
      ???   So, was that a yes to both questions?

You might be able to recenter the valve w/o disassembling or replacing anything.  With the engine off, sit in the captain's chair and hammer the brake pedal with your foot half-a-dozen times, hard and fast, then recheck it with the test light to B+ as you did before.  Sometimes, the jolts from your foot will jostle the spool sufficiently for it to recenter itself inside the combination valve.  You may have to repeat several times, but it generally works.  If it doesn't then try to locate a replacement valve before removing the old one.  There is no reason to replace any other parts until the combination valve issue is resolved.
Rich
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In other words... if people learn by making mistakes, by now I should know just about everything!!!
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Offline zieg85

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Re: Which brake booster?
« Reply #16 on: August 03, 2015, 10:05:33 PM »
      ???   So, was that a yes to both questions?

You might be able to recenter the valve w/o disassembling or replacing anything.  With the engine off, sit in the captain's chair and hammer the brake pedal with your foot half-a-dozen times, hard and fast, then recheck it with the test light to B+ as you did before.  Sometimes, the jolts from your foot will jostle the spool sufficiently for it to recenter itself inside the combination valve.  You may have to repeat several times, but it generally works.  If it doesn't then try to locate a replacement valve before removing the old one.  There is no reason to replace any other parts until the combination valve issue is resolved.

and for those really stubborn ones, a second set of hands are handy by tapping on the valve with a small ball peen hammer.  I have always been able to re-center those valves.  My $.02
Carl 
1985 C20 Scottsdale 7.4L 4 speed 3.21
1986 C10 under construction
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Offline Irish_Alley

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Re: Which brake booster?
« Reply #17 on: August 03, 2015, 11:23:39 PM »
might not have to replace anything there is a button on one side of the combination valve.  It is under a rubber cap.  Pushing it in will reset the Pressure Differential Switch
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Offline gunrac

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Re: Which brake booster?
« Reply #18 on: August 04, 2015, 05:49:50 AM »
      ???   So, was that a yes to both questions?

You might be able to recenter the valve w/o disassembling or replacing anything.  With the engine off, sit in the captain's chair and hammer the brake pedal with your foot half-a-dozen times, hard and fast, then recheck it with the test light to B+ as you did before.  Sometimes, the jolts from your foot will jostle the spool sufficiently for it to recenter itself inside the combination valve.  You may have to repeat several times, but it generally works.  If it doesn't then try to locate a replacement valve before removing the old one.  There is no reason to replace any other parts until the combination valve issue is resolved.

I do not believe Brake warning lamp is working at all.
The dash wire was still connected to the valve, and I had only tapped into the wire itself w/the test lite. Heading out shortly to bang on brake peddle.

might not have to replace anything there is a button on one side of the combination valve.  It is under a rubber cap.  Pushing it in will reset the Pressure Differential Switch

the only rubber I see is where the wire goes onto the top of about a 1" rubber piece......I assume the wire will separate from the top of it? Not sure that is why I did not disconnect. I'm not sure if wire pops straight up or not..
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Offline gunrac

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Re: Which brake booster?
« Reply #19 on: August 04, 2015, 06:51:05 AM »
might not have to replace anything there is a button on one side of the combination valve.  It is under a rubber cap.  Pushing it in will reset the Pressure Differential Switch

k'.....I found the button .....faces toward the drivers side......pushed it several times......no difference........even after pecking on housing while holding in

also smacked the brake peddle 6 to 8 times.......letting set an hittin again, several times.......not looking good
 
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Offline gunrac

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Re: Which brake booster?
« Reply #20 on: August 04, 2015, 07:03:59 AM »
k.....got a helper.......while holding button in........i had him mash brake peddle a couple times......could feel movement coming back thru.......if this means anything......
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Offline zieg85

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Re: Which brake booster?
« Reply #21 on: August 04, 2015, 06:56:13 PM »
Sounds like it moves now.  Did you loose brake fluid in the rear?  If so get your helper again and you will have to bleed the front one more time.  It will make a bit of a mess but you need to open both front bleeders, then mash the pedal to the floor but don't let up.  Have your helper close the bleeders then you can let up.  That should center the valve and keep it there.
Carl 
1985 C20 Scottsdale 7.4L 4 speed 3.21
1986 C10 under construction
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Online bd

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Re: Which brake booster?
« Reply #22 on: August 04, 2015, 07:57:44 PM »
Once you get the combination valve spool centered and finish bleeding the brakes, you'll need to figure out why the dash light isn't working and repair that too.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline gunrac

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Re: Which brake booster?
« Reply #23 on: August 04, 2015, 09:06:19 PM »
thx 4 the info fellas........workin the ol' girl now.......knowin its not correct........good enough to make a buck........go back into it over weekend.......it needs fixed.........
thx

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Offline gunrac

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Re: Which brake booster?
« Reply #24 on: August 11, 2015, 07:50:53 AM »
Sounds like it moves now.  Did you loose brake fluid in the rear?  If so get your helper again and you will have to bleed the front one more time.  It will make a bit of a mess but you need to open both front bleeders, then mash the pedal to the floor but don't let up.  Have your helper close the bleeders then you can let up.  That should center the valve and keep it there.

Got a little time today........are u saying i should open both front bleeders at the same time, mash the brake, hold an tighten both bleeders? Then go thru the whole system again? Just making sure I'm understanding u correctly.
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Offline zieg85

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Re: Which brake booster?
« Reply #25 on: August 11, 2015, 09:01:14 AM »
Sounds like it moves now.  Did you loose brake fluid in the rear?  If so get your helper again and you will have to bleed the front one more time.  It will make a bit of a mess but you need to open both front bleeders, then mash the pedal to the floor but don't let up.  Have your helper close the bleeders then you can let up.  That should center the valve and keep it there.

Got a little time today........are u saying i should open both front bleeders at the same time, mash the brake, hold an tighten both bleeders? Then go thru the whole system again? Just making sure I'm understanding u correctly.

Yes, that will center the valve
Carl 
1985 C20 Scottsdale 7.4L 4 speed 3.21
1986 C10 under construction
https://www.facebook.com/groups/248658382003506/