[Gillybbm]

Hi there, I have just joined as I have an i30 petrol that I've owned for a year and a half. Over the last 2 weeks there have been a number of times that the brakes just haven't worked. The pedal goes to the floor but then they work fine again next time. My local mechanic has had it twice now and found nothing wrong. There are no lights on and it shows nothing on the diagnosic machine. It's had 2 new tyres, new brake pads, discs cleaned. Very nervous driving it as never know if it will happen again. Typically it hasn't happened when the mechanic has driven it.
I did notice on here that Katie has experienced the same although there's no grinding with mine. Sorry should have said my name's Gillian and was just wondering if any others have experienced this and if anyone has gotten to the bottom of why? Thanks

[Dazzler]

Hi Gillian and Welcome.

Really sorry to hear of your issues. Intermittent problems are the worst (safety ones even more so!)

I can understand you being nervous! 

I can't really help in this situation, but it may help others to know a bit more about your car.

What year is it? What series? Series 1 = FD, Series 2 = GD and Series 3 = PD

What mileage has it done?

[nzenigma]

Im afraid I will probably be repeating what your mechanic has said.

1. It remains a mystery. It cant happen. 

2. The brake hydraulic system is split in two, each section acts independently on two of the four wheels. Therefore you always have at least half your brakes working.
 
3. Your brake pedal first pushes a vacuum activated servo device that adds extra pressure to the hydraulic system.
If that fails, you get a hard pedal, but still have brakes.

4. The only way the pedal will go to the floor is if you have air in both the hydraulic lines. That will remain and will be obvious to the mechanic.

[Dazzler]

In that case should Gillian take it to another mechanic or a brake specialist? 

[nzenigma]

In that case should Gillian take it to another mechanic or a brake specialist? 

By all means, she should, even if it is only for peace of mind.

If the complaint was a hard pedal, then I would have a few suggestions.

But "The pedal goes to the floor but then they work fine again next time" would indicate air in the system.

By " they work fine again next time" does she mean consecutive attempts to brake? In that case she is pumping the brakes so that fluid gets past the air lock.. Thats normal bush mechanic procedure.... until you get  home and can bleed the brakes. You see the air coming out
of the bleed nipples at the wheels.

"a number of times that the brakes just haven't worked" if there is air in a line, it is more likely that the sensation will seem like no brakes.
 at all.  But, the point is, once the brakes fail, they keep failing; once air is in the line, its there permanently or until its bleed out by a professional.

P.S. An observant mechanic should see the air and any wetness where fluid is leaking out and air in.

[TerryT]

Im afraid I will probably be repeating what your mechanic has said.

1. It remains a mystery. It cant happen. 

2. The brake hydraulic system is split in two, each section acts independently on two of the four wheels. Therefore you always have at least half your brakes working.
 
3. Your brake pedal first pushes a vacuum activated servo device that adds extra pressure to the hydraulic system.
If that fails, you get a hard pedal, but still have brakes.

4. The only way the pedal will go to the floor is if you have air in both the hydraulic lines. That will remain and will be obvious to the mechanic.

Re #1. above.  After reading the symptoms posted by Gillian/Gillybbm, my thoughts exactly.

This will be an interesting one to follow to its conclusion.

[Gillybbm]

Hi again, sorry I havent been back on for a while. The car is a 63 plate Series 2 and has done 41000 miles.  My mechanic gave everything a good clean, said there was a lot of dust and dirt round the pump. After he did that the brakes were great for about a month and I really started to get my confidence back with the car. Did a good lot of miles in that month then all of a sudden, driving home from Callander, a cyclist was on the road so I had to brake and nothing!! The pedal just goes down and down with no feeling of pressure then sort of kicks in right at the floor. It happened 3 times in the space of 10 miles the next day. He blasted it with air to remove any dust iagain thinking it must be electrical connections but it failed again on the way home and I havent driven it since. I took my parent's car to go on holiday. I'm now home and  donnt want to upset my mechanic but I think I'll have to contact a Hyundai garage. My fear is that it's going to cost me a fortune for them to say there's nothing wrong but I'm now foo scared to drive it. It's a horrible sensation. 2 different people I've spoken to say it's got to be something to do with a diaphragm??

[asathorny]

OK,  I am gonna stick my neck out all the way here Gillian...

This is the longest of long shots and you'll hate me but, you're not mixing up the pedals, are you????

OK, I've got my old WD tin helmet on and gas mask ready for you to blast me out.

 But like everyone else, including you, I am baffled.

Good luck and, no offense intended

 

Mechanic gave a good clean around the pump, how's that going to help what about bleeding the brakes to remove air from the lines

[Surferdude]

OK,  I am gonna stick my neck out all the way here Gillian...

This is the longest of long shots and you'll hate me but, you're not mixing up the pedals, are you????

OK, I've got my old WD tin helmet on and gas mask ready for you to blast me out.

 But like everyone else, including you, I am baffled.

Good luck and, no offense intended

 

Pedal is "kicking in" right at the floor.
Clutch pedal won't work the brakes no matter how far down it goes.
However, once when i was very young a friend let me drive his father's automatic.
Pushing the brake pedal like you would a clutch sure locks everything up in a hurry. 

[nzenigma]

Pushing the brake pedal like you would a clutch sure locks everything up in a hurry. 

 
dont feel bad mate:  first auto car I drove in the USA, my brain was thinking manual box, I shifted from 1st to 2nd gear (= Drive to Park). The sales rep broke his nose on the windscreen. 

Most of the Brit car's are manual gearbox. But Gillian hasn't confirmed this. Maybe she does not have a clutch pedal.

@Gillybbm . The so called "diaphragm" is in the servo mentioned above. The servo assists the braking action. If if fails, the pedal becomes harder to push down. If it fails , it stays failed.

From what you are saying, the actions of the mechanic tell me that he is just doing something- anything, to justify his time.

I have some sympathy for him, because the brake system is not up there with rocket science. Your car has a relatively simple and therefore, extremely safe and foolproof system.

It is basically the same system all other vehicles use. Therefore going to the dealer is of no advantage.

I would try another experienced mechanic .

[mickd]

@Gillybbm
Agree with the points that diaphram failure causes HARD pedal, damn HARD.
Blowing some air around is absolutely useless.
Remove the cap on the brake reservoir ( your cars handbook should show you where it is, get someone to double check if unsure- use a cloth when removing lid ).
 Check the level of brake fluid to check how much and what colour it is.
( take a pic and if it's a different colour or level after next mech touches it, you'll know something has been done)
Full or not, system needs to be bled properly, the only other low percentage part that could be the cause would be the master cylinder having seal/o-ring  problem.
As far as NOT upsetting your mechanic, he is endangering your life and others.
If he doesn't know, he should say so.
If this problem results in an incident,  never mention it .
Please keep us posted 

[nzenigma]

to Mick 

[The Gonz]

 

[BrendanP]

The only problems I've had with brakes not working is 1) having air in the pipes because I hadn't bled them properly, causing the  car to pull to one side and 2) leaky seals in the master cylinder of a Fiat Uno. That was alarming.

[Gillybbm]

A quick update to my brake issues. A brake/ABS specialist has found a 'swan neck' in the wiring  and a fault is showing up in the harness at the pump if that makes sense. Hopefully get good news soon.

[Dazzler]

A quick update to my brake issues. A brake/ABS specialist has found a 'swan neck' in the wiring  and a fault is showing up in the harness at the pump if that makes sense. Hopefully get good news soon.

Hopefully not to expensive to rectify. 

[nzenigma]

A quick update to my brake issues. A brake/ABS specialist has found a 'swan neck' in the wiring  and a fault is showing up in the harness at the pump if that makes sense. Hopefully get good news soon.

Hopefully not to expensive to rectify. 

I add several more

ABS pump = pedal to floor. Thats......... ............ a thought

[nzenigma]

A quick update to my brake issues. A brake/ABS specialist has found a 'swan neck' in the wiring  and a fault is showing up in the harness at the pump if that makes sense. Hopefully get good news soon.

@Gillybbm

Ive been chewing this over. Mainly because it does not make sense and secondly, we are all being very polite.

This needlessly puts your neck in a noose.

The specialist's story about a "swan neck" ( = kink ??) in the wiring loom has no bearing upon your pedal going to the floor.

He could simply prove me wrong by disconnecting the wires from the pump. His problem is that your brakes will still work.

A quick google search re ABS will typically reveal, "If the ABS packs up, you should still have normal, unassisted braking, so it's safe to continue your journey."

Gillian , I have assumed that you have a manual transmission car, not automatic. Is this correct?

[Gillybbm]

Hi , sorry, missed all these replies as they had gone into my spam folder. I know nothing about cars so I'm now scared to say anything because I'm probably saying the wrong things. The guy who has my car at the mo is a brake /pump specialist who has found a fault somewhere. Hopefully it will come back fixed and with a proper explanation I can relay to you guys. Yes my car is manual. All I know is that every now and again there was no pressure on the brake pedal. Very scary . Sometimes there would be 3 weeks between it happening but sometimes it happened 3 times in one day.

[Shambles]

missed all these replies as they had gone into my spam folder.

Hi.

No idea why your "spam folder" would receive replies, but if you wish to subscribe to replies you need to hit the "notify" link on the topic header