Please! My brakes!!!!
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Senior User
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Please! My brakes!!!!
My 2000 f250 brakes are hard on the pedal, dont go to the floor,and you have to stand on them to make them work. And I've replaced power steering pump, brake booster and bled em 5 times. What the hell could it be?? Please guys some one knows the morsel of infor I need. I replaced the cab on this truck and the brakes have never been the same! Help!
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how does the power steering feel? It will take a while to bleed the air out of the system to make the power brakes work. You have to continuously add power steering fluid until all the air is out. How long ago did you do the powersteering pump? Hope this helps.
Timmy
Timmy
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From: Charlotte-Fairbanks-Bflo
While bleeding them, I assume you were using a helper. If so, was the pedal going to the floor when you released the fluid? To tell you the truth, I read on here all of the time and have never seen the problem before.
Fleet Owner
Joined: Aug 2001
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From: Drummonds, TN USA
It sounds to me like VACUUM is missing.
NO DIESEL ENGINE develops vacuum on its own - a VACUUM PUMP is used to make vacuum, and if it has leaks in itself or the lines, the power brake booster does not have the vacuum it needs to apply assist force.
I'd grab (or borrow anyway) a vacuum guage to read the line going into the brake booster and troubleshoot from there on...
NO DIESEL ENGINE develops vacuum on its own - a VACUUM PUMP is used to make vacuum, and if it has leaks in itself or the lines, the power brake booster does not have the vacuum it needs to apply assist force.
I'd grab (or borrow anyway) a vacuum guage to read the line going into the brake booster and troubleshoot from there on...
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Here ya go man straight from the service manual:
<table border="1" cellpadding="3" cellspacing="0" rules="groups" width="90%"><tbody><tr valign="top"><td>
</td> <td>
</td> <td>
If power steering pump pressure is not available at the Hydro-Boost power brake booster, check the power steering pump pressure and flow. For additional information, refer to Section 211-00.
On a Hydro-Max booster system, if power is available at the electric pump and no power assist is felt, replace the Hydro-Max booster assembly and retest the system.
If power is not available at the electric pump, correct the electrical concern and retest the system.
Accumulator, Hydro-Boost Only
The function of the power brake booster check valve is to allow manifold vacuum to enter the power brake booster and prevent the escape of vacuum in case manifold vacuum is lost during sustained full throttle operation.
To test the function of the power brake booster check valve :
<table border="1" cellpadding="3" cellspacing="0" rules="groups" width="90%"><tbody><tr valign="top"><td>
- Excessive brake pedal effort
- Brake booster.
- CARRY OUT the brake booster component test in this section.
</td> <td>
- Brake booster check valve.
- CARRY OUT the check valve component test in this section.
</td> <td>
- Brake booster manifold vacuum hose.
- REROUTE, REPAIR or INSTALL new components as necessary.
- With the transmission in NEUTRAL and the engine stopped, apply the brakes several times to exhaust the vacuum in the vacuum boost system or the pressure in the Hydro-Boost system.
- Hold the brake pedal in the applied position.
- Start the engine.
- If the power brake system is functioning correctly, the brake pedal can be felt to move downward after the engine starts.
- With a vacuum type power brake booster, if engine vacuum is available to the power brake booster and no power assist is felt, replace the power brake booster and retest the system.
If power steering pump pressure is not available at the Hydro-Boost power brake booster, check the power steering pump pressure and flow. For additional information, refer to Section 211-00.
On a Hydro-Max booster system, if power is available at the electric pump and no power assist is felt, replace the Hydro-Max booster assembly and retest the system.
If power is not available at the electric pump, correct the electrical concern and retest the system.
Accumulator, Hydro-Boost Only
- Start and run the engine.
- Stop the engine.
- Apply the brakes. The accumulator in the Hydro-Boost power brake booster should retain enough pressure for at least two power assisted brake operations. If no power assist is felt, replace the Hydro-Boost power brake booster and retest the system.
The function of the power brake booster check valve is to allow manifold vacuum to enter the power brake booster and prevent the escape of vacuum in case manifold vacuum is lost during sustained full throttle operation.
To test the function of the power brake booster check valve :
- Start and run the engine for at least 10 seconds.
- Operate the brake pedal to check for power assist.
- Disconnect the vacuum booster hose from the power brake booster. Do not remove the power brake booster check valve from the power brake booster.
- There should be enough vacuum retained in the power brake booster for at least one more power-assisted brake operation.
- Replace the power brake booster check valve if it fails the above test.
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From: Charlotte-Fairbanks-Bflo
I don't think our power brakes are run off of that little vacuum motor. I damn sure would not want to count on that for brakes to stop a 7000 pound truck. If there is another vacuum pump this too is something I've not heard about. How can the power steering pump create a vacuum? I think our power brakes are hydraulically boosted.
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Fleet Owner
Joined: Aug 2001
Posts: 29,941
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From: Drummonds, TN USA
I don't think our power brakes are run off of that little vacuum motor. I damn sure would not want to count on that for brakes to stop a 7000 pound truck. If there is another vacuum pump this too is something I've not heard about. How can the power steering pump create a vacuum? I think our power brakes are hydraulically boosted.
It has nothing to do with brakes.
* (?) Oops.....
(Just trying to be helpful)
Originally Posted by markadeck
Boy, I sure wish I had not posted what I just did.
I saw the above when it came back.
Gone, but not forgotten
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From: Charlotte-Fairbanks-Bflo
Then why do you lose your brakes as soon as you blow your belt off?
Fleet Owner
Joined: Aug 2001
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From: Drummonds, TN USA
Because it (the belt) drives the vacuum pump for the system.
Typically - a diesel will have a small plastic globe used as a vacuum accumulator.
It can spring a leak too.
In my old '85 it (the pump) was mounted on the curb side of the Timing case, and it was on it's second one.
Typically - a diesel will have a small plastic globe used as a vacuum accumulator.
It can spring a leak too.
In my old '85 it (the pump) was mounted on the curb side of the Timing case, and it was on it's second one.
Senior User
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most if not all 7.3s will only have the hydro system which uses power steering fluid to build pressure in your hydro boost system which acts almost identical to a full hydraulic system. On a relic of a diesel (not in a bad way) like greys 85 yes they use vacuum but not very reliable or good at braking