Filling a hydroboost setup

[Waverous]

I have a new hydroboost setup on my bronco that has never been filled. Can I gravity fill the setup through one of the ports on the hydroboost unit? I was hoping to cut down on some of the time and mess when bleeding the system.

 

[toddz69]

I guess you could but I'd just fill the system through the PS pump.

Todd Z.

 

[Waverous]

I guess you could but I'd just fill the system through the PS pump.

Todd Z.

Yeah, I guess you're right Todd -thanks

 

[T-7ToNewOldB]

Good instructions on this online. Just google. There are some peculiarities to this process that may be counter-intuitive.

 

[Waverous]

Good instructions on this online. Just google. There are some peculiarities to this process that may be counter-intuitive.

I will do that - my interest is peaked

 

[Green_Bastard]

This video has detailed instructions

https://www.youtube.com/watch?v=CzdxEYSVJ4U


Sent from my iPhone using Tapatalk

 

[DirtDonk]

As in any hydraulic system, keep the tight bends to a minimum and avoid any loops in the lines.
Just generally a good practice I think.

Paul

 

[Speedrdr]

I guess you could but I'd just fill the system through the PS pump.

Todd Z.

Wait...what??? Fill the brake system through the power steering pump? Obviously I’ll have to google this as well because I’m definitely curious now. I’m thinking I may be glad to have a vacuum boost on my ‘77.
Randy

 

[DirtDonk]

Haha! Yeah Randy, more fun stuff to learn about.
The hydro-boost setup is really nothing new, but it is in more recent years that it has become more popular as a swap into vehicles not originally so equipped.
More powerful than a small booster (probably about the same as a reallllly big booster though) in a smaller package. Once you get to 33" tires you're on the borderline for some, so by the time someone has 35's they can really benefit from hydro-boost braking.

So yes, definitely check it out. But no, you are not putting the fluid where the brake fluid goes. Same fluid in the master cylinder, but more power steering fluid because the p/s pump is what powers the hydro-boost.
Hence the name...

Oh, and as far as I'm concerned the factory booster on a '77 was probably the best of the small boosters for it's day. Lots of the new ones are good, but don't have quite as much assist as the old ones.
So if you're ever in need of a new one, I would personally have a local specialty shop rebuild your original.

But with bigger tires, it's all about hydro-assist!

Paul

 

[Broncobowsher]

Master bleeds just like any other brake master. Nothing special there.

Power steering, well it bleeds pretty much like any other power steering system. Just a few more bits in the line. Takes a bit to burp the foam out of the fluid. But once burped it is done. My typical burping process starts with topping the power steering, start the engine and shut of the moment it starts. Cranking speed isn't enough to move fluid. Top off the power steering again. Wheels in the air, lock to lock. repeat several times. Once you get some fluid in the system you can push it through by cycling the steering box. Add a little drag (front tires slightly on the ground, enough that you load the spool valve in the steering box but not so much that it is hard to turn. Lock to lock several more times, keep the fluid topped off. Another engine start. Top off the fluid as needed, pause when the fluid is foamy (trying to get air out of the system, not send it back in). Eventually you will be at a running engine, turn lock to lock, cycle the brakes, and you are not needing to top off the fluid any more.

 

[RonJones]

Master bleeds just like any other brake master. Nothing special there.

Power steering, well it bleeds pretty much like any other power steering system. Just a few more bits in the line. Takes a bit to burp the foam out of the fluid. But once burped it is done. My typical burping process starts with topping the power steering, start the engine and shut of the moment it starts. Cranking speed isn't enough to move fluid. Top off the power steering again. Wheels in the air, lock to lock. repeat several times. Once you get some fluid in the system you can push it through by cycling the steering box. Add a little drag (front tires slightly on the ground, enough that you load the spool valve in the steering box but not so much that it is hard to turn. Lock to lock several more times, keep the fluid topped off. Another engine start. Top off the fluid as needed, pause when the fluid is foamy (trying to get air out of the system, not send it back in). Eventually you will be at a running engine, turn lock to lock, cycle the brakes, and you are not needing to top off the fluid any more.

Kudos to this write-up! I tried several other procedures on my newly installed Cobra hydroboost, including a couple Cordone procedures, but it just made foam! No problems bleeding before previously putting on a Saginaw pump with a vacuum booster, but the hydroboost and associated plumbing made it more challenging. A couple things I suggest as well.

After running the engine, pump the brake pedal 5 times, to get all the air out of the hydroboost accumulator. Do this before adding fluid as it will raise the resevoir fluid level.

After you think you are ready to start moving the wheels while the engine is running, first just move the steering wheel just enough to feel something about to happen as the hydraulics start to put pressure on the slightly dragging wheels without actually moving them. If you do it gently enough, you can avoid foaming.

 

[ransil]

I had most luck putting the return line in a bucket after messing around turning wheels for an hour, cracking the line loose might work but I was trying to avoid a mess, its messy either way.