Author Topic: Changed booster, master, distribution block and hold off valve - Won't bleed  (Read 651 times)

MrGrinch

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So I replaced the booster, master, distribution block and hold off valve with all new parts. I bench bled the master before installing. I hooked up all the lines and went to bleed the brakes, starting at the farthest wheel. I have tried manual bleeding with someone pumping the brakes, I tried a handled vacuum pump and also a vacuum assisted (compressor) bleeder and I am not getting any fluid. I have tried the other rear wheel and then the drivers front wheel and I get no fluid from any of them. I've checked several (not all as some are hard to get to) of the connections going in and out of the master, dist. block and hold off valve and each will leak fluid when I depress the pedal. I am not a mechanic and don't know what else to try. Any help would be greatly appreciated. Thanks!

69 Camaro
Front Disc / Rear Drum

z28z11

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Welcome to the CRG -

Given the working master. I'd say the downstream side is the roadblock. Lest I assume too much, what parts did you use from whom, new calipers and brake cylinders, new or old lines, flush the system before charging ? There are many threads on here concerning rebuilding brake distribution blocks and proportioning valves, which are really suspect in your case. I've heard of failures in new aftermarket and repro parts right out of the box; "new" doesn't always guarantee "works".

I'm sure we can field many theories and suggestions - give us some additional info when you can.

Regards,
Steve
1968 Z28 M21/U17 BRG/W
1969 Z28 X77/M20/VE3 LeMans/W
1969 L78 X66/N66 Cortez/BVT
1969 Z11 L48/M35/C60/C06

MrGrinch

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Hey Steve, thanks for the response and taking the time!

Nothing else was replaced except the aforementioned items. I did not flush the lines. The items were purchased from Inline Tube Company. I'm sorry I don't know anything more about the mfg., brand or quality.

Mike S

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 You're dealing with two separate reservoirs so I can't see both sides of the M/C being bad. The distribution block is passive with a centered plunger so nothing there can block all 4 ports. And the hold-off valve would effect only the front if that were bad.  Plus, you were able to bench bleed the M/C so that sounds like the pistons are moving past the compensation ports to build pressure.  Is the pushrod on the brake pedal adjusted correctly to the new M/C?

Mike
67 LOS SS/RS L35 Hardtop - Original w/UOIT
67 NOR SS/RS L35 Convertible - Restored

olddragracer

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One of the first things I would check is the brake light switch on the distribution block. Check the terminal on the switch with a test light or ohm meter. If it checks going to ground that means the valve inside has stroked and is cutting off fluid to either 2 front or 2 rear wheels.

Dusk Blue Z

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Try taking out the bleeder screws one at a time and see if get any fluid when you press the pedal slowly. I had the right rear wheel cylinder hole behind the bleeder plugged and it drove me nuts because that's the first one your supposed to bleed.

Not sure if you changed the three rubber lines, but they can fail over time, crack the hard lines in front of them if you don't get any fluid with the bleeder screws out.

william

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I've checked several (not all as some are hard to get to) of the connections going in and out of the master, dist. block and hold off valve and each will leak fluid when I depress the pedal.

If they leak under pressure, they are drawing air in when the pedal is released. First order of business here is to fix the leaks. We chased our tail on a similar situation years ago. Turned out the line at the back of the distribution block was drawing air but didn't leak fluid.

Another common problem is mounting the front calipers on the wrong sides.

dbaker55

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Just did this complete job on m 69 Z28 last week. I bled the master cylinder first by using the bleed ports on top of the master cylinder into a container. Took about 12 ounces of fluid to finally get all the air out of the master cylinder before going to the brakes. From there I bled all 4 wheels starting with the furthest away from the master cylinder. I used the 4 bleed rule and filled the half of the master cylinder back up after every 4th bleed as to not run the level too low. Sometimes it took 4-5 tries to get the fluid to start to come out of the bleed ports. Make sure who ever is pumping the brakes does not release the pedal until you have the port fully closed otherwise you will be sucking air into the system and chasing your tail. Last tip is to make sure the pedal is being fully depressed (to the floor) by who ever is pumping it. I had my wife doing it and after pulling the seat all the way forward things went a lot smoother from there.

Hope this helps
1969 Z/28 Bought 2-8-2019

KurtS

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...after pulling the seat all the way forward things went a lot smoother from there.
Too funny!
I like the rule of 4 bleeds - nothing sucks like running the master dry.
Kurt S
CRG

z28z11

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One other thing to remember, whether you bleed with a helper or use a vacuum assisted bleeder - keep the drain line from the bleeder valve(s) immersed in a jar under an inch or so of fluid, or it will draw air back into the system before you can close the bleeder. Unless you are very quick, and have a "tuned" helper -

Regards,
Steve
1968 Z28 M21/U17 BRG/W
1969 Z28 X77/M20/VE3 LeMans/W
1969 L78 X66/N66 Cortez/BVT
1969 Z11 L48/M35/C60/C06