Brakes suddenly not working

Just after some ideas and tips :thumbsup:

Was driving normally on the way to work. Stopped at a few lights then the next time I went to brake, the pedal just sank to the floor without doing anything.

After overcoming the shock and managing to engine brake and hand brake to a near miss on a HWY, I soon discovered the brake still had a bit of bite in the last inch of play (usually the pedal would sit a good 3" above the floor, but here it was only 1" above).

This inch of movement had barely any progression and went from no braking to almost full lock. When using the brake this way, the car pulled violently to the left.

I checked brake fluid and it was at about 1/4 capacity.

I received the car back last friday after all rotors and pads were replaced and all four calipers were rebuilt. Braking worked ok under light load over the weekend, but seemed to pull to one side or wobble from side to side when braking more heavily. I thought it was probably due to totally dodgey wheel alignment, but maybe brake related in retrospect.

I haven't found any liquids/leaks in the interior under the pedals and nothing obvious around the master cylinder. Haven't jacked the car up yet, so haven't checked brake lines.

Anyone got any ideas what could be the problem?

Mastercylinder. Bleed the system first and see how that goes.

Turn off the engine and pump the pedal a few times does the pedal get harder?

fatboy, when the engine is turned off and I pump the pedal, it definitely gets harder. What does this signify?

im guessing it is your master cylinder, because i had same problem with the leaking master cylinder, brake pedal sank to the floor when at lights or something and had to keep pumping. With the wobbling part of things, it could be warped rotors? but then you had them replaced so im not quite sure. but the sinking part i would say is master cylinder

I guess wobbling or leaning to one side could be proportioning valve, a burst hose on one side, air on one side... dunno what else...

if your hose bursted, your brakes wouldn't work at all, because all the fluid is gone.
when you pump the pedal when the car is off, hold it down, and see if it goes down, if it does, your seals insiude youe master cylinder are gone.
get a rebuild kit, if that's the case.
and get it done asap, becuase the more you drive like so, the more damage you can do to the bore inside where the pistons are in the cylinder, and if it is too damaged, you can't rebuild it, and you will have to get a new master cylinder.

destrukshn: your theory explains the pedal sagging, but does not explain the unpredictable pulling to the side when braking.

Seems pretty likely it's the master cylinder, but it's probably something else as well, like proportioning valve? Or maybe there isn't even a problem and there's just air in the brake lines on one side?

How can I tell what is causing the pulling to one side? I tested it on smooth surfaces at various speeds and pressures on the brakes. It happened on all tests, except very light/progressive braking.

Not ruling out warped rotors, but it seems highly unlikely, given they are new.

Have you bled the brakes again? Do that first.

pullling to one side....hmmm trying bleeding the brakes again. Something doesn't sound right.

Could be mastercylinder but mayb there's a big air pocket in the brake system. Bleed the brakes again cause its a cheap option.

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Originally Posted by Dylanamus

I received the car back last friday after all rotors and pads were replaced and all four calipers were rebuilt.

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Have you at least contacted the place that did the work?

could it be a large air pocket that escaped/formed?

Must have been a bloody scary experience. Good thing your ok tho :thumbsup:

bleed it again. like jimmy says its a cheaper option. Car serving to a side could be caused by air inside the brake line on the side that the car swerves to. Air causes one side to be more biased that the other. Oh and don't go back to the mechanic that did your brakes for you ever again.

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if your hose bursted, your brakes wouldn't work at all, because all the fluid is gone.

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thats not exactly true, unless 2 or more hoses have burst. cars are still able to brake as the brake system has been designed with failures in mind.

i'd get the brakes bled and check ur new rotors for warping. also, check the caliper sliding bolts to make sure they are both moving, if one is jammed, it will force the pads on at an angle, which could cause the car to swerve under braking. and check ur hoses for crackes etc.

I think the piston on one side is rooted and fluid might be slowly leaking out, more so under pressure.

Well I bled the lines and there was leaking in engine bay, but couldn't pin point it, so due to it being the biggest suspicion, I bought a brand new Master Cylinder.

Upon inspecting the old Master Cylinder, I realised it was in perfect condition - even looks freshly rebuilt. So I'll be selling a 15/16 Nissin MC if anyone wants one.

I then got a mate to pump the brakes so I could inspect/feel for leaks. I didn't even need to feel, as it was pretty damn obvious - fluid was literally squirting from the cetntre seal in the Proportioning Valve.

A quick trip to Hondaworld and $30 worth of PV later, the problem was fixed good and proper. Used 750ml of Castrol Dot 4 fluid, which was under $20 for 1L.

I thought about reusing the old MC and cleaning out the new one for a refund, but I had already bled it in, so I thought I'd just sell the old one.

I really did bleed the system thoroughly and now the pedal stiffness and response is a lot better than both before and after the mechanic worked on the car. She doesn't pull to the side or shudder anymore either.

Should have been a $50 fix, but not to worry! Thanks for everyone's input and help.

Diy Ftw

The proportioning valve was literally squirting. So the pulling to one side would have been air introduced into the system and the sudden "no more braking" was when there wasn't enough fluid left. I replaced the master cylinder and proportioning valve and bled the lines properly and all is well.

Yeah mate, Was gunna say you got a leak.
Pedal to the floor equates to air in the system.
Because it happened so rapidly (whilst driving) the line must of burst LOL. If u did something to ur brakes and it happened, would just mean that air got in them.
To answer the earlier question, when ur engine is off, and u pump your brake pedal, if it goes harder after each press down, this is signifying that the "brake pressure cylinder" is functioning.

NB-Brake pressure cylinder- Cannot remember exact name of the thing, its in my haynes manual, pretty much testing the pressure...will fix this post when i have a chance with proper terminology.

Quote:

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Originally Posted by FAT VTI

If u did something to ur brakes and it happened, would just mean that air got in them

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Well the work done immediately before the problem occured was done by a "mechanic", not me. It just caused me to not trust other people with my car, so I fixed it myself and have been attempting to DIY most things since.

Quote:

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Originally Posted by Dylanamus

Well the work done immediately before the problem occured was done by a "mechanic", not me. It just caused me to not trust other people with my car, so I fixed it myself and have been attempting to DIY most things since.

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Yea,
Mate i do not think you can blame a mechanic for that one though.

If a line bursts, its the nature of the material used. Unless the mechaic bent the piping, or in some way affected the piping then that would be a different story but yeah, DIY for the win.
Funny thing , same thing happened to me, 1 of my p/s pipes split whilst driving, round a round about then "oh shit, my steering is hard". Stopped the car, checked everything and there was no fluid. Poured in fluid turned it on, it all disappeared. The p/s pipe that was split was actually just inside the front bumper, so all the fluid was right under the car. Anyways, wrapped duct tape and a spills kit bandage around it, drove it home.
I replaced the p/s pump-just becoz i didnt like the idea it was on without fluid, was prob still alright.
ended up costing $50 for the pipe and a p/s pump. Installed myself, 10xxxkms later and going well.

Strange coencidence. It wasn't just the brakes though. Certain filters I supplied were claimed to be installed and clearly weren't. Rear trailing arms suddenly changed size and even at maximum positive toe adjusted they are still 18mm total toe out. mmm When a few things like that add up, you just lose confidence. Anyway the only thing separating us from mechanics is a few tools and the "give it a go" spirit. So why not!

LOL
Mate, I agree with you on the most part.
However, I still have 1 highly accredited mechanic, who i go to for anything i cannot work out.

Yeah it's good to have a good mechanic as a backup. Now that i've moved out in the bush, there's a bloke down the road who's pure oldschool. He let me use his hydraulic hoist to fix a few problems recently :thumbsup: