Help with hydroboost issues, no P/S or P/B

[eviltwin_1987]

I am having an issue where I don't have working power brakes or power steering. Hoping for some advise on what to look for. The truck runs and steers like it has manual steering and manual brakes. The pedal is nice and firm and returns no problem. I have bleed the system with the engine off, turning the wheel back and forth a hundred times while pumping the brakes. This brought the fluid level down and then I refilled it. But I have no P/S or P/B. Bleed it with the engine running as well with no difference. After topping off the reservoir, bleeding it with the cap off would cause some fluid to rise in the reservoir and out the top. The pump is silent during all of this operation so I'm assuming its pumping fluid. Here is my setup.....

-'53 Chevy Truck
-'12 CTS-V LSA engine, power steering pump and brembo brakes.
-S-10 steering box.
-Astro van hydroboost UNDER the floor with C3 corvette master. The hydroboost is oriented with the pressure lines facing down.
-custom crimped -6 hydro lines, no AN lines
-return for both hydroboost and steering box are Teed together under the pump with one line that goes up to the reservoir.

The brakes in the CTS-V worked flawless before I took that car apart. The hydroboost was on a previous truck of mine and also worked without issue.

I have read about people not Teeing the two return lines and tapping a second hole for separate returns in the reservoir. Is that something that would cause this issue? Could it be an issue that the hydroboost is the lowest point in the system so its has air that cant be pushed out? Any help would be greatly appreciated.

[Hydratech®]

Everything sounds correct, though it sounds as though your PS pump has decided not to produce pressure. Rev the engine up while you have the steering wheel turned and see if any steering assist comes into play. If the steering boosts up for a second when you rev the engine up, then the assist dies off as the engine returns to idle, this is an indicator that the pressure regulator valve is stuck inside of the pump (into max bypass). In some cases, you can disconnect the line from the PS pump then take a (clean) drill bit of about 1/8" sizing and stick it into the PS pump's output port - you should be able to feel a spring loaded piston that you can push in and release. If all you feel is a dead stop with no movement or spring back, then yank the PS pump's pressure output fitting out of the pump and see if you can coax the pressure relief valve into moving, hopefully popping out so that you can clean and polish it. Make sure you put it back in the exact way that it came out, making sure that it can slide freely in the bore that it operates in. If it does, then re-install the PS pump pressure output fitting, reconnect the high pressure line, fill the system again, then cross your fingers that everything comes to life. It could very well just be a fleck of debris hanging up your pump's pressure control valve (hopefully).

Let us know how this goes for you!

:smoke:

[eviltwin_1987]

Thank you, I will try that this weekend. I did have the fitting for that off during mockup so good chance I screwed something up.

[eviltwin_1987]

Ok, so I did what you said and got no movement. Pulled the pump and this is what I’m working with. Pics are the factory fitting that screws into the pump and the inside where the fitting goes. This is on the stock CTS-V LSA pump made by ZF.

[eviltwin_1987]

And here is a pic with the piston pulled out. The arrow points to where the spring pushes the piston into the pump. Can someone please clarify if that is the correct orientation of the spring and piston? I don’t remember the piston ever coming out but I could just not remember it and maybe I installed it all backwards??

[eviltwin_1987]

Ok, the more and more I look around, it looks like I installed it in the wrong order. I put the spring between the fitting and the piston when it sound be the fitting, then piston, then spring. Which would confirm why I could not get it to move when sticking a drill bit in the fitting.

[Hydratech®]

Spring goes into the pump first, then the round pressure control regulator valve with the FLAT END OUT, then the PS pump's output fitting = done.

That should get you going - let us know how it goes!

[eviltwin_1987]

Yep. Definitely had it in wrong. Works like a charm now! Thank you.