Images restored above in:
Post #3
And Post #5
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Thanks subford. I really appreciate that a lot.

 

Thank you Subford
You ROCK!

 

I'm having a similar problem on a 1995 F600 5.9 12v with Lucas Girling brake system.While idling with park brake applied the brake and park brake light will flash and the electric motor will come on while the lights flash.When they come on the pump will groan like it is in a bind. Someone has just replaced hydroboost and the pump and rewired a new light switch in.I have bleed the canisters in back and got a good bit of air but when the pump groans the resevoir seems to be bubbling air. Does anyone have a troubleshooting guide for the system? Can subford repost your pics, especially the warning light fault guide. Thank you for any help

 

Photos restored above in post #3 & #5.

 

Thank you subford.. Now I can figure out what I'm looking at.

 

I would like to add this for the people who keep finding this thread who are having the buzzer issues: Mine was caused by a chewed in half wire at a pressure sending unit. Some critter got up in there and chewed several wires under the hood, this being one of them. Freaked the system out, caused it to think it had no pressure, causing the warning buzzer to stay on. It's kinda buried back there, hanging upside down. Just look around and check and make sure that all of the wires are where they should be.

Hey Subford! Do you remember how I said I have other vehicles I had to tend to? Well, now it's the F-700, "Thomas". So here I am trying to address it's issues and I'm searching for the answers and I find myself in yet another thread where you are again! You really get around! Seriously, God bless you for all of the help that you give!!!

My only question on this system should be a fairly easy one but I can't find anybody that knows for sure. Even the Ford truck dealer service people weren't much help. (As with cars, if it's more than 10 years old, they're stumped.)

Here it is: What cotton-picking fluid does this system take? The reservoir has a sticker right on it that says it wants 15W-40 diesel motor oil, not trans fluid like normal hydro-boost systems take. (I say "normal" to mean the ones that share fluid and a pump with the power steering system, which this system does not.) I smelled it and it definitely smells different than what the fluid in the power steering system smells like. That power steering fluid most definitely smells like trans fluid. But all this means is maybe the previous owner was putting 15W-40 motor oil in there too, since that's what the sticker says, and maybe this is why the system is leaking now. I'm thinking that maybe that's just the motor oil sticker for the engine, there being no other suitable spot near the oil filler spot to put the motor oil sticker. It also doesn't help that this 21 year old sticker is partially missing. But I'm also thinking that maybe this really does take motor oil, this being such a different system being a system solely dedicated to just the brakes having both a hydraulic pump AND an electric pump PLUS having the additional job of running that locking parking brake mechanism in back. And it just sounds like the Ford dealer people are just guessing when they say "trans fluid".

I'm already having enough trouble right now, I don't need to compound it by putting the wrong fluid in this thing. It's very low, it's going to take at least a quart, which I fear is enough to hurt something if it's the wrong stuff. Plus, it smells like it already has motor oil in it, adding to the problem, if indeed it should have trans fluid.

As always, any and all help is much appreciated!

Regards,
Eric

 

Filling Hydro-Max with Fluid

1. With the engine off and the parking brake applied, fill the reservoir of the engine-driven hydraulic brake pump, supplying the Hydro-Max booster. Use Motorcraft MERCON® Multi-Purpose Automatic Transmission Fluid XT-2-QDX or -DDX or MERCON® equivalent.

2. Crank the engine over several times. Use either remote starter switch or ignition key.

3. Check and refill the reservoir. Crank the engine over several times again.

4. Refill the reservoir to the level indicated on the dipstick of the engine-driven brake pump reservoir. The Hydro-Max, hydraulic lines and engine-driven brake pump should now be filled with fluid.

5. Refer to Adjustments, Bleeding the Parking Brake System of «Section 06-05B» for additional information.

CLEANING AND INSPECTION
Hydro-Max Booster

Use clean automatic transmission fluid, Motorcraft MERCON® Multi-Purpose Automatic Transmission Fluid XT-2-QDX or -DDX or MERCON® equivalent for cleaning and lubricating parts and seals.

1. Inspect the power piston input and output shaft surfaces for scratches or nicks. Also, check that the large piston seal surface is smooth and continuous without excessive wear. If any wear or damage are found, replace the power piston assembly. Confirm that the check ball is in place and is clean and free to move. Confirm that the reaction piston bore and poppet valve seat surface inside the piston are clean and undamaged.

2. Inspect housing for grooves, scratches or nicks in the input bore area. If any are found, replace the housing. Minor wear, as indicated by a shiny appearance on the large bore surface area, is normal.

3. Inspect the input plug for wear in the actuator pin hole. Replace the plug if wear is evident.

 

Thanks subford!

I forgot to mention that this is a 94, but you saw that in my sig correct?

I'm curious, does your 94 F53 chassis use the same brake boost set-up?

 

No it does not, my F53 uses the Bendix Hydro-Boost system.

DESCRIPTION AND OPERATION of the Bendix Hydro-Boost system.

The Bendix Hydro-Boost brake booster is a hydraulically operated brake booster powered by the power steering pump. The power steering pump (3A674) provides the fluid pressure to operate both the hydraulically-powered power brake booster (2005) (hydro-boost) and the power steering gear (3504).

A hydro-boost reserve system (compressed gas accumulator) stores sufficient fluid under pressure to provide at least two power-assisted brake applications in the event the power steering pump fluid flow is interrupted.

The brakes can also be applied manually if the reserve system is depleted.

With the Hydro-Boost at rest (engine on, brakes released) oil flows from the inlet (pump) port, across the number 3 land and out the gear port. In this position, steering pressure created by the steering gear and power steering pump is isolated from the boost cavity by the spool valve. Lands 2 and 4 block this steering pressure avoiding activation of the unit.

Any leakage goes directly back to the power steering oil reservoir (3A697).

 

I have a 1989 F-800 with the Lucas Girling brake system. The line that comes out of the hydromax into the Hydraulic relay is building up too much pressure I believe. I put a new line on it that was rated at 315 PSI and it started to bubble out of the side like it was about to blow. I then went back to the part store and got a higher rated psi hydraulic hose. After running for 15 minutes with the parking brake on it, blew the line off. Since it's a stronger line a normal hose clamp would not hold it. I went and got a better hose clamp put on it and it appears to be holding now but still believe it is building up too much pressure. I've took off all the lines and made sure none were stopped up or collapsing. Then made sure the electric pump wasn't running while the engine was running. I'm stumped. The brakes will pump off back Brakes when the parking brake is off but it is making a constant straining or whistling nose when the E brake is off. If you press the brake hard the sound will stop until you let your foot off the brake. If you put the parking brake back on the whistling sound will stop. I might add that this truck has been sitting for 7 years. I've had to change the 2 back parking cylinders due to leaking but they are fixed now. Everything is working properly except the brake issue. Any ideas?

 

I know this is old, but subford, could use please repost those pictures and diagrams of the brake system. I have a light on and would like to troubleshoot it.

You truly are awesome with your mighty knowledge moutain

 

Images restored above in post #3 & #5.

 

Awesome thanks

 

1987 F700 with similar brake issues.Is it possible to publish the procedures for bleeding the parking brake systems. Thank you.