Brake problems!!!! Please Help!
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Senior User
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From: Oregon
Brake problems!!!! Please Help!
1991 F-250 4x4.
I was driving and they worked fine, then all of the sudden they didnt work and the brake light came on. The fluid did not leak out. The pedle is still firm and doesnt go to the floor. It felt like the back ones worked a little.
So I changed the master cylinder today and bleed all the air out of the system. Now the pedle is firm again and I thought I fixed it, untill I took it out for a drive, and its the same thing. The pedle is hard, there is no air in it. And the back brakes work, but nothing from the front.
Whats wrong?
Thanks,
Lars
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I was driving and they worked fine, then all of the sudden they didnt work and the brake light came on. The fluid did not leak out. The pedle is still firm and doesnt go to the floor. It felt like the back ones worked a little.
So I changed the master cylinder today and bleed all the air out of the system. Now the pedle is firm again and I thought I fixed it, untill I took it out for a drive, and its the same thing. The pedle is hard, there is no air in it. And the back brakes work, but nothing from the front.
Whats wrong?
Thanks,
Lars
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Junior User
Joined: Nov 2003
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From: Talladega, AL.
Sounds like you have a bad vaccum pump. If the belt is on it, pull a line off and give it the old test. You should feel the vaccum. You can get them at the parts store, but must have a puller to remove and replace the pully. Don't attempt it with a hammer.
Junior User
Joined: Nov 2003
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From: Talladega, AL.
You should have around 14 to 16 inch pounds, if you have a gauge to place in line. You will see in a hurry.
I have experienced this many times. You will have a hard low pedal. Brakes are there, but you have to mash HARD to get them.
With the 91, you are "blessed" with the E 4 OD. The older ones with the C 6, needed 13 inches to the moudulator, or it would never shift right, making you think the transmission was bad.
Good Luck!!
Les
I have experienced this many times. You will have a hard low pedal. Brakes are there, but you have to mash HARD to get them.
With the 91, you are "blessed" with the E 4 OD. The older ones with the C 6, needed 13 inches to the moudulator, or it would never shift right, making you think the transmission was bad.
Good Luck!!
Les
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From: Talladega, AL.
It's possible, but check the vaccum first, that is the easiest. Also see if the vaccum line going to the booster is free. Sometimes with age, the inner walls of the line will collapse. Also look for possible leaks (cracked lines)in the vaccum system. Heat and years take their toll on them.
Thread Starter
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Senior User
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From: Oregon
The Vaccum is 10-12 both at the pump, and at the booster.
Is this too low? If it is what is the next step? Change the pump?
Also I was looking for the valve in the brake line and couldent find it. Is it in the master cylinder?
Thanks for your help.
Lars
Is this too low? If it is what is the next step? Change the pump?
Also I was looking for the valve in the brake line and couldent find it. Is it in the master cylinder?
Thanks for your help.
Lars
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Junior User
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From: Talladega, AL.
On the E series the valve is underneath on the frame. My experience with them has given a disapearing pedal. You can pull the spring out and see if it makes a difference. That valve is kind of pricey.
The book says 15-19 inches of vaccum at idle in neutral. If you have only 10-12, you are too low.
Les
The book says 15-19 inches of vaccum at idle in neutral. If you have only 10-12, you are too low.
Les
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From: Springfield, VA
On the E series the valve is underneath on the frame. My experience with them has given a disapearing pedal. You can pull the spring out and see if it makes a difference. That valve is kind of pricey.
When you say "disapearing pedal" do you mean that it gets soft and goes away? I have changed my master cylinder out, bled the lines about a dozen times (gravity and using my helper to bleed), bled the RABS and master cylinder several times for each), adjusted the rear shoes, put new calipers and pads up front and I still have no good brakes. I checked the vacuum and am getting good pressure. I have brakes, but I need to pump the pedal 1 or 2 times before they get firm, then next stop light they are soft again. Got any clues for me? Oh, and I have checked for leaks, ther are non that I can see.
If I can't figure it out soon, next stop is the brake shop. I know that brake fluid is chaep, but I have gone thorugh about 1 1/2 gallons of fluid so far (my wife thinks I am drinking the stuff, cause I always need to run to the store) and no luck.
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From: Oregon
I just took my truck to the brake shop. 198 bucks for the air pump, and 90 bucks labor to install pump and power bleed. They might get it done today.
I wish I would have taken it there first instead of putting the new master cylinder on for nothing.
Lars
I wish I would have taken it there first instead of putting the new master cylinder on for nothing.
Lars
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Joined: Nov 2003
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From: Talladega, AL.
Karl,
On the antilock valve, there is a 15/16 nut (cap) remove that and pull the spring out. Replace the nut. See if that helps.
Lars,
The pumps are 107 here in Alabama. Pretty easy swap. At the price your shop is charging, you could have bought the pulley puller/installer set and had some change left.
Les
On the antilock valve, there is a 15/16 nut (cap) remove that and pull the spring out. Replace the nut. See if that helps.
Lars,
The pumps are 107 here in Alabama. Pretty easy swap. At the price your shop is charging, you could have bought the pulley puller/installer set and had some change left.
Les
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From: Oregon
Thanks for all your help, I think the shop gave me a good price on the pump because I called 3 differant auto parts stores here in Oregon and they were all over $215 just for the pump!
I got the truck back and it works great, $280 bucks.
Lars
I got the truck back and it works great, $280 bucks.
Lars