Intermittent random brake failure

[BUDFORCE]

Before going further, yes I will take it straight to the garage.

However, knowledge is power right?

So, in January had a seized brake caliper, replaced, car was fine for a while. About 3 weeks ago driving on the A1, went to brake, pedal just went to the floor, no pressure, no braking. Fortunately I didnt need to slow down in any major hurry, so after about a second or so, releasing, re-applying pressure, brakes then worked, and continued to do so.

Thought, meh, wierd, but one off, been driving the car 3 weeks no problems.

Today, oddly, (but I doubt related), also driving down the A1, went to brake, same problem, all be it this time the ABS light came on.

Googled and there is little, found two threads detailing exactly the same problem, and she went and had the ABS unit, master cyclinder and brake booster changed, none of which solved the problem. All pretty expensive mitsubishi parts, unfortuantely my car isnt that common for parts.

Now, I pretty much garantee the garage are going to test everything they can, and find no fault.

Ever been doing 90 on a motorway and pushed the brake pedal fore nothing to happen? it's a disconcerting feeling I tell you.

Anyway, can't drive a car that will do that, might kill you, or someone else. I'll give the garage a go, but reckon I'lll need a new car.

Damn annoying, its a Mistsubish Lancer Equippe 07 plate, 110k mileage, which I have had since 30k miles and has otherwise been faultless, and although not worth much now, its a damn good car, real shame if I have have to get rid of it.

 

[NoobCannon]

Sounds like brake booster to me. Altho wierd to be that intermittent

Pedal going straight to the floor is usually air in the system, could be a caliper/seal gone bad somewhere

Does the pedal go straight to the floor or theres still pedal but no immediate breaking?

 

[BUDFORCE]

Sounds like brake booster to me. Altho wierd to be that intermittent

Pedal going straight to the floor is usually air in the system, could be a caliper/seal gone bad somewhere

Does the pedal go straight to the floor or theres still pedal but no immediate breaking?

No pretty much to the floor with no braking at all, there is no pressure behind the pedal either, like it just goes straight down with nothing/no weight behind it. Almost like if you had no brake fluid at all.

 

[jpaul]

yes I will take it straight to the garage.
..... About 3 weeks ago driving on the A1, went to brake, pedal just went to the floor,

really, and you didn't do it then ... then driving at 90 - that's considerate ...April 1 is soon.

 

[NoobCannon]

No pretty much to the floor with no braking at all, there is no pressure behind the pedal either, like it just goes straight down with nothing/no weight behind it. Almost like if you had no brake fluid at all.

And then it comes straight back afterwards?

Do you know what a break booster looks like? Check the vacuum connection to it from what is usually the inlet manifold.

 

[Slam62]

Did you check the brake fluid level? You could just be pumping it out

 

[BUDFORCE]

And then it comes straight back afterwards?

Do you know what a break booster looks like? Check the vacuum connection to it from what is usually the inlet manifold.

Yeah pressure comes back after, literally just goes down once, no brakes, let off the pedal, then push the pedal down again and brakes work. It's fine, unless that one random time I need to stop ina hurry quickly the first time, it does it, then that split second to release and put the brake back on is plenty enough to give you a real ****** up day.

As I said, literally done it twice in say, 1000 miles? 500 at least. fortunately both times I didnt need to stop in a hurry.

 

[NoobCannon]

Do you know what your looking at with cars? As i said above do you know what the break booster looks like

 

[Slam62]

Have you checked the physical connection between pedal and cylinder?

 

[BUDFORCE]

No I've just come home and it's dark, I know a little but not enough to start messing with that stuff.

 

[NoobCannon]

No I've just come home and it's dark, I know a little but not enough to start messing with that stuff.

If you cant/dont know what your looking at get it recovered to the closest garage. If you drive it and it happens at the wrong time everything would be 1000 times worse for youself

 

[BUDFORCE]

If you cant/dont know what your looking at get it recovered to the closest garage. If you drive it and it happens at the wrong time everything would be 1000 times worse for youself

Oh yea. I'll keep you all posted and let you know what they say.

 

[jpaul]

Do you know what a break booster looks like?

if the servo assist went it, you have to apply more pressure ?
moreover maybe the fluids old and it's boiled if he's been driving/braking @90 .. but presumably fluid was changed following calliper change.

 

[agw_01]

Surely if the brake booster had failed, it'd just mean that was no assistance. The pedal would be harder to push rather than dropping to the floor?

Sounds like air in the brake lines.

 

[BUDFORCE]

if the servo assist went it, you have to apply more pressure ?
moreover maybe the fluids old and it's boiled if he's been driving/braking @90 .. but presumably fluid was changed following calliper change.

Yes, I don't see how you even could change a caliper without changing the fluid, also both times the brakes failed was not following a period of heavy braking, the opposite if anything, driving along probably not using the brakes at all for say 10 minutes of driving.

 

[agw_01]

They could have just clamped the hose with some mole grips, replaced the caliper and bled it, topping up the fluid along the way.

Depends on the garage and the quality of their workmanship.

 

[Finglonga]

Master cylinder or servo on the way out.

 

[red eye]

Yes, I don't see how you even could change a caliper without changing the fluid, also both times the brakes failed was not following a period of heavy braking, the opposite if anything, driving along probably not using the brakes at all for say 10 minutes of driving.

Keep the brake pedal pressed or clamp the hose (not with mole grips) when changing the caliper, stops it leaking and makeing everything slippery.

a fluid change is not a workshop consumable like copper grease, customer has to pay for fluid and labor. Depending on location people don’t like spending £35-40 on brake fluid, even when the fluid looks like something has taken a dump in it.

I’ll bet you an internet beer op hasn’t had a fluid change since 2009

 

[Munchies]

Could be the disc the seized caliper was on is warped, and kicking the pads away from the disc, first press brings them back close to the discs, second pump they make contact. Especially if you drove it with a seized caliper.

 

[BUDFORCE]

Keep the brake pedal pressed or clamp the hose (not with mole grips) when changing the caliper, stops it leaking and makeing everything slippery.

a fluid change is not a workshop consumable like copper grease, customer has to pay for fluid and labor. Depending on location people don’t like spending £35-40 on brake fluid, even when the fluid looks like something has taken a dump in it.

I’ll bet you an internet beer op hasn’t had a fluid change since 2009

Hah, incorrect! I did it, hmmm about 3 years ago. I'm not completely inept with cars but I know my limits and what I don't want to mess with, something like this is one of those things.

I did read one thing though which kinda did make a little sense and was to check bearings.

If you think about it, motorway driving, not braking, slight wobble pushes the piston back, right back into the caliper, so when you brake, it has to travel so far your pedal goes right down before you get any pressure, and need a second "pump" for the piston to start pressing against the back of the pad. I will mention that.