Break pedal is stiff
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Senior User
Joined: Jul 2006
Posts: 207
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From: Sandy Lake, MB
Break pedal is stiff
I have a 91 7.3. a little while back my breaks got hard so i replaced the vacuum pump (which was no longer pumping) with another one. It is putting out approx 19 psi. Now it is a little less stiff and it goes nearly right to the floor. When it comes back up it hisses. Any ideas???
Senior User
Joined: Aug 2006
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thats what my problem was. Not the stiff part, but the all the way to the floor part. It was a bad valve at the break booster. I replaced the valve(check valve I think) and the grommet. I also replaced the large vacuum line and it fixed the problem.
jeremy
jeremy
Elder User
Joined: Oct 2005
Posts: 500
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From: Angleton Tx.
Originally Posted by 2New2Fords
thats what my problem was. Not the stiff part, but the all the way to the floor part. It was a bad valve at the break booster. I replaced the valve(check valve I think) and the grommet. I also replaced the large vacuum line and it fixed the problem.
jeremy
jeremy
The problem you were having sounds the same as mine. The pedal will bleed down to the floor and the vacuum booster seams to be working, I dont have to stand on the pedal to stop but again it bleeds to the floor.
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 15
From: Nutter Fort, WV
Could be a bad master cylinder. I have replaced mine and had worse brakes in 30 miles of driving than I had before I replaced it.
Lots of bad parts out there in new boxes for new prices.
A couple of mechanic friends of mine say that about 25% of their replacement parts that are bad right out of the box.
Lots of bad parts out there in new boxes for new prices.
A couple of mechanic friends of mine say that about 25% of their replacement parts that are bad right out of the box.
Junior User
Joined: Aug 2006
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Originally Posted by Dave Sponaugle
Could be a bad master cylinder.
I have also had bad master cylinders. I had 3 bad ones(new) when I was working on my Dodge Magnum(78 I think not the station wagon). I was so mad when I found out the 3rd one was bad I left if full of brake fluid when I took it back. Then they had the nerve to tell me they would give me another one & not my money. I was not going to go for that so after some arguing I got my money went some where else & never had a brake problem on that vehicle.
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Elder User
Joined: Sep 2006
Posts: 561
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From: Edmonton, Alberta Canada
From my experiences, a spongy break usually indicates that there's air in the lines. Also, if you're pushing it down to the floor, your breaks themselves could worn out? I think what Dave said is probably another true factor too.
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Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 15
From: Nutter Fort, WV
I have found that if I hit the brakes hard and have good pedal and good stopping power but when I am just barely resting my foot on the pedal to keep from rolling and it goes slowly to the floor that the master cylinder is leaking internally.
If that is the case it will keep getting worse, but the fluid will never be low.
I have had three or four do that over the last 10 years.
New parts today don't last 1/10th as long as the originals made back in the 80's did.
If that is the case it will keep getting worse, but the fluid will never be low.
I have had three or four do that over the last 10 years.
New parts today don't last 1/10th as long as the originals made back in the 80's did.
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 15
From: Nutter Fort, WV
Just for that reason when I go buy parts anymore I will pay more for a part with a warranty before I will pay less for one that does not have one. I took one apart that failed in less than a day, it was full of metal shavings from the manufacture process.
The shavings are what cut the seals to pieces. I can not remember where it was manufactured, South America somewhere I think, but they evidently have no quality control in the plant.
The shavings are what cut the seals to pieces. I can not remember where it was manufactured, South America somewhere I think, but they evidently have no quality control in the plant.
Post Fiend
Joined: Nov 2004
Posts: 5,638
Likes: 1
From: Manitoba
Many brake problems arise after brake pad and shoe changes and especially after bleeding brakes. The worst thing you can do is bleed the brakes and push all the way to the floor on an old Master Cylinder.......always place a 2x4 or similar on the floor under the pedal. Reason is every time you floor the brake pedal on an old reliable M/C you introduce dirt etc from the bore of the M/C because your travel is now beyond the normal range. This crud then finds its way into RABs valves, wheel cylinders etc etc.
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Senior User
Joined: Jul 2006
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From: Sandy Lake, MB
I forgot to mention this before but i put new pads and rotors in the front and when i bought the truck it had a broken brake line that ran to the back breaks. i got it all bled and it was stiff. Also when i push it first thing in the morning when everything is still cool, it isnt 100%, but it goes down alot easier. when i pump it a couple times it is still stiff but does not go to the floor. Drive or leave the truck for a while and right back to the florr unless i pump it a couple times again.