H-boost no brakes or pwr Steering

[bronco italiano]

Well this is the build from Hell!!!
Got the fuel issue sorted out finally.

Now I have no brakes or pwr steering.

-The Hydroboost was an old BCB kit that I have stored for about 15 years
The explorer pump I rebuilt.
When I turn the truck off I do have fluid (not under pressure) at the H-boost High Pressure ports
Brake pedal goes to the floor but the system manually bleed (before start-up) and am not losing fluid as the MC is still full
What a miserable time I am having with this.

Thanks, BI

 

[Shimmy]

everything routed correctly ?

 

[ba123]

So, those are two separate things...really.

You should have brakes even if the HB system is crap. Your pedal should not go to the floor. It should still stop, it will just take more effort than with HB working and on.

I'd tackle the brake issue first. And manual bleeding sucks and not something you should be doing.

Either the cheapo vacuum sucking fluid from the caliper side, or the pressure from the master pushing fluid through. You are welcome to borrow my pressure bleeder if you're coming my way anytime soon...but depends on what master you have as to whether or not it will work.

And back to square 1 if the master is full...have you tried bench bleeding it to make sure it even works?

 

[bronco italiano]

So, those are two separate things...really.

You should have brakes even if the HB system is crap. Your pedal should not go to the floor. It should still stop, it will just take more effort than with HB working and on.

I'd tackle the brake issue first. And manual bleeding sucks and not something you should be doing.

Either the cheapo vacuum sucking fluid from the caliper side, or the pressure from the master pushing fluid through. You are welcome to borrow my pressure bleeder if you're coming my way anytime soon...but depends on what master you have as to whether or not it will work.

And back to square 1 if the master is full...have you tried bench bleeding it to make sure it even works?

I did bench bleed, then manual (attempted reverse bleed with "Phoenix" reverse bleeder garbage), then my room mate at the shop put his pressure bleeder on it. Maybe the master is just bad as it is as old as the H-boost (but I stored it in a temp controlled room. Thanks BA123

 

[bronco italiano]

everything routed correctly ?

I was asking myself that same question and am gonna recheck. I went Pump to inside HP fitting at H-boost and then outside line at H-boost to power steering gear. Since the H-boost doesn't have the accumulator style, I hope the lines are the same as the accumulator type. Thanks, BI

 

[74 Bronco Billy]

This diagram helped me set up my lines, maybe it will confirm something for you. I had trouble with mine for many months, it turned out I had several problems contributing. Check for leaks!! I had one in passenger rear drum cylinder, took it out, rebuilt it. Had rust and crap in it from sitting for 5-6 years while I finally got my build done. If you have stainle steel lines, check connections. Lastly, those seals in the MC will go bad, and even in a temp controlled room, MOISTURE loves to get into the brake fluid and create rust which will grow and tear up yr SEALS. Might need to rebuild the MC. Hang in there.

 

[bronco italiano]

Here is a pic. I think it is right. Seems the H-boost is from a cadillac or Buick grand national used this type

 

[toddz69]

Here is a pic. I think it is right. Seems the H-boost is from a cadillac or Buick grand national used this type

That's one of the early ones with an internal accumulator - found in diesel Cadillac Eldorados and maybe 1-2 Buicks.

Those were highly prized in the early hydroboost swap days to clear the 5.0 upper intakes like yours - until we figured out you could rotate the external accumulator models and be just fine.

Todd Z.

 

[ntsqd]

I agree, you should have brakes even w/o PS pressure. They won't be great, but they should work.

Did you check the H-B Push-rod to m/c piston fit? There needs to be a small air gap with everything at rest. If the push-rod moves the piston even a tiny, tiny bit then the brakes won't work right, or at all. And they will not bleed or bleed correctly.
I have two m/c's for an H-B conversion that I'm working on right now. Both are the same exact application. One is made from iron and sold by ACDelco. The other is aluminum and was sold by Raybestos. The AL m/c's piston gets depressed ~.02" just by bolting it up tight. That's no good. the iron m/c has about a .007", which is pretty small, but it works. As I want the AL m/c (deliberately choose an application that used one) I am going to make some shims to go between the H-B and the M/C that will establish this air gap.

HP hose on the left in your pictures is from the pump and the HP hose on the right in your pictures goes to the steering box?

 

[bronco italiano]

HP hose on the left in your pictures is from the pump and the HP hose on the right in your pictures goes to the steering box?- Yes
Did you check the H-B Push-rod to m/c piston fit? I will double check that
Thank you

 

[ksagis]

I did bench bleed, then manual (attempted reverse bleed with "Phoenix" reverse bleeder garbage), then my room mate at the shop put his pressure bleeder on it. Maybe the master is just bad as it is as old as the H-boost (but I stored it in a temp controlled room. Thanks BA123

Did you bench bleed with plugged port method or returning fluid to MC pots?

If plugged port method and you ended up with little MC plunger travel, I’d wager MC is fine.

 

[ksagis]

I agree, you should have brakes even w/o PS pressure. They won't be great, but they should work.

Did you check the H-B Push-rod to m/c piston fit? There needs to be a small air gap with everything at rest. If the push-rod moves the piston even a tiny, tiny bit then the brakes won't work right, or at all. And they will not bleed or bleed correctly.
I have two m/c's for an H-B conversion that I'm working on right now. Both are the same exact application. One is made from iron and sold by ACDelco. The other is aluminum and was sold by Raybestos. The AL m/c's piston gets depressed ~.02" just by bolting it up tight. That's no good. the iron m/c has about a .007", which is pretty small, but it works. As I want the AL m/c (deliberately choose an application that used one) I am going to make some shims to go between the H-B and the M/C that will establish this air gap.

HP hose on the left in your pictures is from the pump and the HP hose on the right in your pictures goes to the steering box?

Would 0.020” preload actually cover up MC ports with piston travel? 0.040 to 0.060” seems for sure yes to cover up.

 

[ntsqd]

When there should be a small air gap I think any m/c piston displacement is a bad thing. The size of those transfer ports varies from one m/c to the next. Most are pretty tiny, so it doesn't take much.

 

[toddz69]

The preload thing seems to vary from configuration to configuration with the OEMs. The Super Duties are like that - a bit of preload required to seat the master on the booster. Somewhere I have some info on the various factory setups and how much preload they do or don't have. Paul at Hydratech used to recommend a little bit but later changed his recommendation to no preload and a small air gap instead. It's one thing when the OEMs are doing it and when we DIY guys are putting together masters and boosters that didn't originally play together.

Todd Z.

 

[Broncobowsher]

While everyone is working on your brakes, the power steering...
Looking at those lines, I bet you have an adapter in the pump to adapt the metric threads to a -6 hose. That fitting in the pump is 98.57% chance of being the problem. Most of the adapters are too long and will press against the pressure relief valve inside the pump causing it to open and go into internal bypass. The only off the shelf one I know of is the Lee power steering version. I never heard of anyone doing it, but I guess you could shorten the too long one and use it?

 

[ntsqd]

Had no idea that any OEM set-ups had pre-load in them. The tolerance stack of such a requirement would be very problematic. A .01" air gap itself, even witha Scout II pedal (7:1 pedal ratio) would be difficult to detect as the pedal need only move .07" to take up the gap. A pedal with a more normal ratio would move even less, making detection even harder.

The m/c piston has to move far enough to close off the transfer port before any pressure will be generated. Assuming that hole is huge, let's say, Ø.06" that means that the pedal must move a minimum of .3" (5:1 pedal, typical for PB), .36 (6:1 pedal, typical for MB). A Ø.03" hole size would be half that. And these calcs assume that the hole isn't already partially occluded by the piston seal, which some designs do feature. If the hole is partially occluded by the m/c piston's rear seal then the displacement needed to close off that hole will be even less.

While everyone is working on your brakes, the power steering...
Looking at those lines, I bet you have an adapter in the pump to adapt the metric threads to a -6 hose. That fitting in the pump is 98.57% chance of being the problem. Most of the adapters are too long and will press against the pressure relief valve inside the pump causing it to open and go into internal bypass. The only off the shelf one I know of is the Lee power steering version. I never heard of anyone doing it, but I guess you could shorten the too long one and use it?

BINGO! I'd forgotten all about that little gotcha. I recall looking into shortening one the non-compliant fittings a long time ago and deciding that it was just easier to order the Lee PS fitting.

 

[bronco italiano]

While everyone is working on your brakes, the power steering...
Looking at those lines, I bet you have an adapter in the pump to adapt the metric threads to a -6 hose. That fitting in the pump is 98.57% chance of being the problem. Most of the adapters are too long and will press against the pressure relief valve inside the pump causing it to open and go into internal bypass. The only off the shelf one I know of is the Lee power steering version. I never heard of anyone doing it, but I guess you could shorten the too long one and use it?

They are the Lee pwr steering fittings
Very interesting note on that!! Thanks

 

[bronco italiano]

Did you bench bleed with plugged port method or returning fluid to MC pots?

If plugged port method and you ended up with little MC plunger travel, I’d wager MC is fine.

Returned fluid to MC reservoirs
What is the plugged port method?

 

[ksagis]

Returned fluid to MC reservoirs
What is the plugged port method?

Plugged port method is close off the outlets of MC with plugs and manually stroke the piston. When fully bled in, can maybe depress piston 0.030” to 0.050” before it becomes rock hard. No false positive that its fully bled in.

 

[bronco italiano]

I bought another MC and am going to plug port bleed it tomorrow and put it on and re-bleed.
I did note a minute spec of fluid at the H-boost at the brake pedal rod insertion. Not enough to make a drip though.