Hydratech Brake boost

[jlipman]

I am new to the board. I recently purchased a barn find. It's a 72 C10 that has been parked for 10 years. The PO did a lot of work on this truck. It has a 383, lowered, bagged and quite a few 1/2 completed installs.
One of them is the Hydratech Brake assist. I'll tell you what I know to see if that sheds any light on what is going on. I checked all of the lines and they are plumbed correctly. I bled the master cylinder in place. I attempted to bleed the brakes using various methods. I tried using a bleeder that pressurized the lines at the master cylinder. I also tried bleeding with the unit that attaches to the bleed nipple on the drum and pulls the fluid. I cant get fluid to the rear drums.
Also, my brake light is on. When the engine is started and I apply the brake and release it, it does not return to the original position.
Any help would be appreciated!

[jjzepplin]

Proportioning valve stuck? Pics of the master cylinder would help.

[jlipman]

Originally Posted by jjzepplin

Proportioning valve stuck? Pics of the master cylinder would help.

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[jlipman]

I'm leaking from the valve on the back of the booster.
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[jlipman]

Originally Posted by jlipman

I'm leaking from the valve on the back of the booster.
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[Orange Crate]

Brake fluid is hygroscopic, meaning it attracts water, so if your truck has been sitting for a long time I am guessing it has water in the brake system, explaining why the light doesn't go out (proportioning valve stuck). The hydroboost system installed is a good system when it is installed correctly and in good shape (overhauled or new). Your hydroboost is installed "upside down" from normal stock installation but it doesn't matter to the hydroboost. Some people like the hoses pointing down and it doesn't affect the operation. I have attached a picture of the ports for you to check that the valve has the pressure and return hoses hooked up correctly. Remember that your system is "upside down" so these ports will be on the bottom, but it should be enough for you to trace them to their connection at the other end (pump pressure, steering gear and return).

[jlipman]

Originally Posted by Orange Crate

Brake fluid is hygroscopic, meaning it attracts water, so if your truck has been sitting for a long time I am guessing it has water in the brake system, explaining why the light doesn't go out (proportioning valve stuck). The hydroboost system installed is a good system when it is installed correctly and in good shape (overhauled or new). Your hydroboost is installed "upside down" from normal stock installation but it doesn't matter to the hydroboost. Some people like the hoses pointing down and it doesn't affect the operation. I have attached a picture of the ports for you to check that the valve has the pressure and return hoses hooked up correctly. Remember that your system is "upside down" so these ports will be on the bottom, but it should be enough for you to trace them to their connection at the other end (pump pressure, steering gear and return).

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[jlipman]

What do you think about the leak?
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[Orange Crate]

ANY leak in a brake system needs to be taken care of. I can't really tell if that picture is the back of the hydroboost valve or the master cylinder, but either way it's not good. Part of "Barn finds" are that components need to be replaced or overhauled, like brake systems, engine seals, tires, battery...I personally would not compromise on the brake system. if you can't repair it yourself make friends with a good local mechanic to help get it on the road (where it should be).

[bs46488]

I did hydro boost on both my projects. Both my projects were not road driven many years prior to my hydroboost install.

Anyways, I had the same issues the Nova was the front passenger side, the C10 was both rear drums.

It wasn't until I replaced almost all the hard lines and rubber lines that I got fluid flowing.

[Overdriven]

Well ignoring the leak, isn't there a button or something you have to push on the proportioning valve in order to bleed and get fluid to the rear brakes?

[jlipman]

Good news. The leak is just the gasket between the MC and the hydroboost. That will be an easy fix. I am going to order a new proportioning valve to eliminate that as one of my problems. I am concerned with how slowly the brake peddle returns after being pressed. I cracked the pressure side of the power steering line at the hydroboost and am getting fluid there. Is the power steering side what should be pushing my peddle back up.
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[Orange Crate]

There shouldn't be any fluid between the hydroboost and the master cylinder. Something is leaking.

You can trouble shoot your hydroboost here:

http://www.brakeandfrontend.com/oper...ssist-systems/

Read carefully and do what they say.

[jlipman]

I pulled the MC off of the hydroboost. There was a bit of rust build up on the bottom of the inside of the hydro and on the inside of the MC where they meet. I'll try to post the pic from my phone. Would you assume I have a bad seal on the MC side and that is where the brake fluid is coming from.
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[jlipman]

Here is a pic

[jlipman]

Pic of the MC

[Orange Crate]

You can replace one component at a time to find out what is actually bad. I would start with the proportioning valve since your brake light is on. If your brakes don't start performing correctly after that I would test the hydroboost with the link I sent earlier, if that works, then replace the master cylinder. If your master cylinder is bad it could affect the operation of the hydroboost, so which one to replace first is a roll of the dice. The hydroboost can be rebuilt very cheaply with a seal kit widely available on the interwebs if you search. There was also some good advice posted here that mentioned having to replace lines and hoses, and that would depend on how long and where the truck was stored. Was it outside for ten years? That is worse than being stored inside obviously. What does the inside of the master cylinder look like? One thing at a time and you'll get there. Do you have any help? Are you able to tackle the hydroboost rebuild yourself?

[jlipman]

Thanks for the advise. I have a new proportioning valve and Master Cylinder. I'm starting there. I'll let you know where I end up. Thanks again for the advise. Now I just need a day to work on it. Btw it was stored indoors. In a barn but indoors. I all looking forward to taking it for a drive!

[rockosocko]

Great info!

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