Hey everyone.
Ever since i did the v8 conversion my brakes have been soft and the pedal goes to the floor when truck is running and when the truck is not running and i pump them up they pump up like normal and are hard, but like i said when truck is on its almost like nothing is there. I have bled the brakes so many times, and have had my mechanic pressure bleed them with a special tool. I put the b303 cam in the truck, don't think that would be why. I put a brake line lock kit in, don't think that matters. all new braided flex lines, calipers, rotors, drums, wheel cylinders, and master cylinder. All that is left is the power booster. I don't get it, please help!

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94 ranger xlt, 5.0L, AOD trans, 3.73 LS rear, B303 Cam, A9L ecu

No offense intended..............when your bleedin them, your doin it with the truck off, right?

If they get hard when bled with truck not runnin, then they get soft when started, sounds like either the booster has gone south or you don't have enough vacuum for the booster, which could be fixed with a vacuum canister.

FFT

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ALL THROTTLE, NO BOTTLE!!!

Favorite quote:
Elvira on Stroker Ace: "I like mechanics, they know how to tinker with things for hours, and makem go fast!"

TOY: Green 94 Pro Street

^^^ ditto

sounds like a vacuum problem

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1996 XLT 2.3L 2wd Factory "Hurst Special" < getting low
1985 XLT 2.8L 4x4 "The Black Pearl"
1987 XL 2.3L 2wd R.I.P.

Check where your brake lines are routed. If they are against the exhaust (or anything that gets hot enough) it causes the brake fluid to "boil" creating gas bubbles, much like having air in the lines.

A bad booster or not enough vacuum will make the pedal harder to depress, not easier.

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1998 Ranger 2WD - 4.6 dohc, Ford prototype intake, custom headers, 4R70W trans, 8.8 rear, 4.10s, trac-lok, aluminum drive shaft, Lakewood traction bars,Mark VIII guages, Explorer buckets, Mark VIII shifter, rear auxiliary fuel tank (no midship), relocated fuel door, fiberglass tonneau cover
http://281ranger.homestead.com
http://www.cardomain.com/ride/2052265

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GOOD INFO, in all my years of toyin with vehicles, I've never heard/been told that!!!

As the sayin goes: "You learn somethin new every day!"

I have a B303 in my Ranger and my stock brake system works fine..

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1993 Ford Tempo 2.3L OHV HSC Auto - D/D Stock.
1988 Ford Ranger - 5.0L AOD Swap.
2002 Dodge Caravan - 3.3L Auto

If you have drums in the rear, try adjusting them a little tighter. Just where the shoes start to touch the drum.

Thanks for all the advice everyone. I bleed the brakes with the engine off. I've heard of the boiling fluid before, i had that problem with my car, don't think lines are close to headers or exhaust. Too much vacuum i feel would cause the brakes to be too soft. If booster goes bad, i think the pedal would be too hard. I have the rear brakes adjusted with slight drag on the drums. What about the line locks in the front? I might take the line locker off just to rule that out. I was even thinking too much vacuum making it too soft. Something is not right because the truck doesn't stop as good as it did with the 2.3L. obviously the V8 is heaver but i read that it was only 150lbs more, like a passenger. and thats not much.

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94 ranger xlt, 5.0L, AOD trans, 3.73 LS rear, B303 Cam, A9L ecu

I don't think there is any moisture in the lines because when the truck is off and i pump them and bleed them, they get rock hard like any other car i've done. and as soon as engine is on they go to the floor.

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94 ranger xlt, 5.0L, AOD trans, 3.73 LS rear, B303 Cam, A9L ecu

ever get the problem solved? Had the same problem and did a complete brake job with no luck, turns out there was a vacuum leak at the booster. Reseated the rubber grommet going into the booster and the brakes came back. They tend to get soft if you repeatedly step on them and reduce the vacuum in the manifold but it should bring the vacuum back up by letting off the brakes within 5 seconds. The other problem could be your booster is bad. Find if you have a leak elsewhere in the system.

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87 Ranger
5.0 (306) from worn out gt mustang
Exploder 31 spline tracloc,linelockin 3:55 rear w/discs
S & R Customs in the works...

no never figured it out. p.s. sorry to respond as late and thanks for trying to help. the thing is, i don,t have any vacuum leak, when i pull out the hose even when truck is off for a while it still get lets off vacuum, so its holding vacuum good. i would think if the booster is bad than it would be really hard or stiff. i did turn up the idol a few hundred rpm,s to what it should be, and it helped a very small bit, i think, but still not right. it was great before the v8 swap and now crap. it is worse at idol than driving down the road i've noticed.

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94 ranger xlt, 5.0L, AOD trans, 3.73 LS rear, B303 Cam, A9L ecu

Guess if youv'e checked the vacuum for the booster, a faulty booster such as a hole in the diaphram would prevent the brakes from grabbing, foot goes to the floor and you would lose vacuum. The only other idea that affected mine was water in the calipers(rusted) but not so in your case since you've had them bled several times. Don't know of what else except for anything that keeps the hydraulic pressure from getting to the brake actuators. Good luck

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87 Ranger
5.0 (306) from worn out gt mustang
Exploder 31 spline tracloc,linelockin 3:55 rear w/discs
S & R Customs in the works...

Thanks for the help! Maybe I will replace the brake booster some time.

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94 ranger xlt, 5.0L, AOD trans, 3.73 LS rear, B303 Cam, A9L ecu

try changing you master cilinder it might be week

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1992 ranger 5.0 5 speed 373 gears makes a fun toy
1998 ranger x cab v8 conversion ohc crown vic dome light explorer sport gauges mp3 20% tint clear dimond head lights smoked tails 16'' mustang wheels flowmasters tano

I've already replaced the master. Is it possible to have a new one that is defective?

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94 ranger xlt, 5.0L, AOD trans, 3.73 LS rear, B303 Cam, A9L ecu