no brakes/ very weak

[lariat 7.3]

ever since i bought the truck back in 2009 the brakes have felt pretty weak. I replaced the master cylinder about a year ago and it didnt make a difference. Compared to the two other 7.3s ive driven mine absolutely suck, its not safe. Sometimes towing trailers i cant stop. When hitting the pedal it sits right above the rubber ball feeling thing, even at lights to keep from moving. Flushed the power steering, no difference. Pump doesnt whine and wheel isnt that hard to turn. What should i be looking at? Hydro boost?

 

[ToMang07]

ever since i bought the truck back in 2009 the brakes have felt pretty weak. I replaced the master cylinder about a year ago and it didnt make a difference. Compared to the two other 7.3s ive driven mine absolutely suck, its not safe. Sometimes towing trailers i cant stop. When hitting the pedal it sits right above the rubber ball feeling thing, even at lights to keep from moving. Flushed the power steering, no difference. Pump doesnt whine and wheel isnt that hard to turn. What should i be looking at? Hydro boost?

Did you bench-bleed the master cylinder? Bleed all the brakes afterwords? (PR, DR, PF, DF?)

I would suspect the hydroboost. What fluid did you use in the hydroboost/power steering?

 

[rustbucket]

Have you tried bleeding the brakes. If the hydra boost wasnt working you would have a hard brake pedal. I would bleed the whole system its cheap and easy.

 

[POWER-STRUCK]

this is an on going problem that I have seen, sometimes it may take 4 master cylinders to get a good one. does the truck have 4 wheel abs? it could also be the abs unit bypassing. also have seen cheap brakes fade on these trucks so I started using nothing but wagner severe duty or motorcraft pads

 

[lariat 7.3]

yeah i bench bled the unit, i believe it has 4 wheel abs, i can try bleeding them again. I flushed the system with royal purple synthetic ATF. The pads are originals that came on the truck when i bought it. The brakes dont "fade" from heat, they just plain suck. How do i test the ABS unit from bypassing? Do i bleed them when its running, cause i didnt do that before

 

[Arisley]

Just gravity bleed the system. Buy a quart or two of brake fluid, and about 4 feet of clear 1/4 inch tubing. Remove the master cylinder lid. Loosen each bleeder valve on the calipers. Attach a foot of hose to the bleeder and place the other end in a can or jug or whatever you want. Keep an eye on the master cylinder and keep it topped off. When you see new clean fluid running through your drain hoses, you are done. Pull the lines and tighten the bleeder valves.

Do not let the master cylinder go empty, if you do, you have to start over again. Grab a chair, a TV or some good tunes, and a twelve pack of your favorite beverage. This is not a fast operation, but it is a never fail operation.

 

[lariat 7.3]

yeah, i know how to bleed brakes lol, i kept her full and kept pumping till i saw clear with no air, ill try that though, its almost like there isnt enough pressure kicking back on the pedal

 

[Magnum PD]

Yours don't need the vacuum pump for the brakes then?

 

[lariat 7.3]

huh? ^

 

[Arisley]

yeah, i know how to bleed brakes lol, i kept her full and kept pumping till i saw clear with no air, ill try that though, its almost like there isnt enough pressure kicking back on the pedal

If you pump the brake with the bleeder open, you are sucking air into the system when you let go of the pedal.

 

[Arisley]

Yours don't need the vacuum pump for the brakes then?

Super Duty's don't use vacuum, they use hydraulic pressure supplied by the power steering pump. Hydroboost.

 

[Magnum PD]

His sig says F-250. Why I asked.

 

[lariat 7.3]

yeah you know threw some 238/80's in my triton V-10 hahaha

 

[moose99psd]

yeah you know threw some 238/80's in my triton V-10 hahaha

dont be an ass, OBS trucks use a vacuum pump and not a hydroboost system

 

[Magnum PD]

I'm not a SD guy. Didn't know they did away with vacuum boost in the SD's.

 

[lariat 7.3]

not being an ass, was just messing around

 

[machinestheman]

i had a similar issue with a mazda truck of mine a few years back i replaced the master cyllinder three times before i got a good one unfortunatly for me every time i repplaced it i assumed i was doing something wrong so i did the top to bottom bleed and still no results i would try a new master cyllinder again

 

[lincolnlocker]

has the power steering fluid ever been flushed?