Brake issue. Good pedal but no srtopping.

I just about do not have brakes in my 95 Tacoma. I have a good firm pedal but little to no brakes. When I bleed the brakes, the pedal travels all the way to the floor and I get a lot of fluid at each wheel. After that I have a good firm pedal but still no brakes. All new pads installed late last year but no problem until now.

 

Start by checking surface area of the front rotors and rear drums. If there is grease or oil leaking on them, it will cause a problem.

It could also be a bad booster. If a booster goes bad, it will still be a firm pedal but very hard to stop.

 

Thanks. Clean rotors/ drums. Booster works fine.

 

Brake pedal shaft adjusted correctly? Just off the top of my head.

 

Master Cyl issues.

 

This is weird, never heard of anything like this. Are you sure the booster is OK? Really sounds like the booster.

 

KdF: I have yet to take anything apart but I'll check on n disassemble. Thx.

 

Truck Yeah: what's odd is my brake pedal behaves as it always has only halfway through the travel it becomes very firm and will not move no matter how much I push. However if I open any bleeder at any cylinder the pedal goes to the floor with plenty of fluid.

 

Ten Beers: I have tried bleeding the brakes both with the engine running and not running and the booster seems to behave as it always has. I agree this is a very odd problem I've had this truck for 20 years and it's never done this

 

Here's some tests to do to see if the booster is working properly -- it probably wouldn't affect bleeding at all.

http://www.newtonnet.co.uk/coupe/service/webtech/iindex.asp@id=12476

 

Sounds like brake booster to me too. Brake pedal goes to the floor and no stop when the master cylinder goes bad. I have experienced both in the past.

 

Another vote for the booster. If you could push even harder it would eventually stop.
Hard to believe all cars used to come like that (although they had larger piston masters).

 

Thank you for the replies.
IMO the booster is working fine. We have bleed the lines several times suspecting air in the lines due to seeing brake fluid where the reservoir meets the master cylinder. Upon pumping the brakes to build pressure for a bleed at any particular wheel I feel great booster assist for about 3 or 4 pumps, at that point it just stops at mid petal travel (where the pads would 'begin' to apply pressure to the rotors/drums) and the petal stops. Firm. It's not like I'm having to over come the lack of assist from the booster, which I should be able to do anyway ( my first 3 cars did not have power brakes so I remember what that was like-I'm old ) the pedal just stops mid-travel at a hard, firm stop. If i hold the pedal at that point while my helper opens a bleeder, the pedal travels towards to the floor-with booster assist. Close the bleeder and I get 2 or 3 booster assisted pumps as it builds pressure and then *bam* the pedal just hits a brick wall and will not move even if I stand on it, yet I have very little pad travel. I've had to pull this truck home before without the engine running ( no booster assist ) and the brakes worked fine-of course I had to push harder but that is normal when the engine isn't running. Hell, I've bleed the brakes on this truck in the past without the engine running so we could hear each other and didn't have this issue. This is strange.
We are about to change the master cylinder as step one. I'll update then.
Again, thank you for the replies.

 

Seized caliper pistons?

 

Pressure required on a failed booster is significantly higher than on manual brakes. Not a good comparison.

Your calipers are stuck. When the new pads were put on, did you pull, clean and lube the pins? If not, step one.

Or the calipers need rebuilt or replaced.

All you are doing when you open a bleeder is releasing pressure so the pedal will move, because whatever is stuck can't be over come by the hydraulic.

When that is resolved, service and adjust the drums and ebrake as well.

That's my free internet diagnosis.

 

I had a similar issue just recently with my 96. I replaced the front calipers, rotors and pads, bled and all was good. turns out the inside pistons on both calipers were rusted and seized. The Whole insides of the rotors were rusted while the outsides were nice and shiny from use.

 

Clearwater Bill:
You are right p.b. vs non-p.b. was not a good comparison.

 

@Ihave2tacos, so what about those calipers?

 

My money is on the Pistons.

 

New master cylinder made no difference. Same issue. Removed front wheels, pads were not in a bind and was able to move pads/pistons back away from the rotor with a flat bar like when I change pads. Pressing the pedal they clamped the rotor as usual. Pads are still new so I don't have a lot of travel and not sure how I would test if they will advance past their present point. I could remove the pads but don't want to blow a piston out? If I find the old pads-I rarely throw anything away-I will put those in to test travel.
Was unable to move rotors with a breaker bar, seemed normal. Rear is working normally also. I am able to get the rear to lock-up ( with a lot of force on the brake petal ) while in gravel. Still have almost no pedal travel. Looking like I'm going to have to believe it's the booster. Other than the proportion valve it's the only thing left. Not sure of the symptoms of a failed p. valve.
Of course no one in town has a booster for a 4WD or I would have changed that yesterday as well. Still finding it hard to believe I can't over-power/compensate for the lack of the booster with more force on the brake pedal-it's taking about 10-15 feet for the truck to stop at 20 mph.