Crap Brakes! [02 Audi A4 B6]

ION08 · 07-05-2014 10:01am #1

So I got into my car yesterday and the brakes were virtually non-existent! :eek:

Pedal is very soft and pretty much sinks all the way down to the floor and the brakes barely grab!

Pumping the pedal doesn't firm it up at all.

Brake discs are still there ✓
Pads are still there with a good bit of meat left on them ✓
Brake fluid seems to be there (but can't really see down into the reservoir) ✓
No visible brake fluid leaks around calipers ✓

Any ideas

I'll be bringing it to a garage to have it sorted but would like to have an idea of what the issue might be!?

Thanks

VeVeX · 07-05-2014 10:11am

Is it diesel?

jimgoose · 07-05-2014 10:17am

Hmmm. Leak? Master/slave cylinder failure?

ION08 · 07-05-2014 10:20am

VeVeX wrote: »

Is it diesel?

Yeah, 1.9 TDI (AWX)

VeVeX · 09-05-2014 8:40am

ION08 wrote: »

Yeah, 1.9 TDI (AWX)

Sorry for the delay.

Based on the symptoms you describe I'd check the vacuum pump first.

ION08 · 09-05-2014 8:49am

VeVeX wrote: »

Sorry for the delay.

Based on the symptoms you describe I'd check the vacuum pump first.

Thanks Vevex , will definitely look at that first.

Is that what is also known as the "brake Servo" ?

mickdw · 09-05-2014 8:57am

Yes would be worth checking the little hose that feeds the brake servo. Does your pedal behave as if the car is switched off?
If it is a vacuum leak from that hose or indeed lost vacuum for any other reason, you should have brakes but you would have to press the pedal with all you power just to get some effect.

ION08 · 09-05-2014 9:02am

mickdw wrote: »

Yes would be worth checking the little hose that feeds the brake servo. Does your pedal behave as if the car is switched off?
If it is a vacuum leak from that hose or indeed lost vacuum for any other reason, you should have breaks but you would have to press the pedal with all you power just to get some effect.

Yes that's what I thought but its actually the opposite of what I would expect if the brake servo failed. The brake pedal actually goes all the way down with minimal effort , almost as if its over servoe'd but the brake seem to grab with minimal force.

mickdw · 09-05-2014 9:31am

ION08 wrote: »

Yes that's what I thought but its actually the opposite of what I would expect if the brake servo failed. The brake pedal actually goes all the way down with minimal effort , almost as if its over servoe'd but the brake seem to grab with minimal force.

Do you mean the brakes grab hard with little pedal force or the brakes themselves have little force/stopping power.
Try pumping up pedal abit with car off. Holding pedal, start the car and see if pedal sinks.
I guess it's possible that your brakes are suddenly full of air. That could give you a pedal that is very long and soft with terrible brakes.

ION08 · 09-05-2014 9:40am

mickdw wrote: »

Do you mean the brakes grab hard with little pedal force or the brakes themselves have little force/stopping power.
Try pumping up pedal abit with car off. Holding pedal, start the car and see if pedal sinks.
I guess it's possible that your brakes are suddenly full of air. That could give you a pedal that is very long and soft with terrible brakes.

Sorry, I guess I wasn't too clear.

It would be the latter, so long and soft with terrible brakes!

Hmm, I wonder how the system could have gotten full of air over night? There wasn't any progressive decline in effectiveness - one day they were fine, the next day they were terrible!

mickdw · 09-05-2014 9:54am

ION08 wrote: »

Sorry, I guess I wasn't too clear.

It would be the latter, so long and soft with terrible brakes!

Hmm, I wonder how the system could have gotten full of air over night? There wasn't any progressive decline in effectiveness - one day they were fine, the next day they were terrible!

Hard to know. Get them checked out anyway.

Hogan24 · 09-05-2014 9:59am

This happened me once before, it was the brake hose/pipe that had a serious kink in it. Cost me €100 to get fixed.

sunnysoutheast · 09-05-2014 5:30pm

Hi, had a similar problem with my 03. The problem turned out to be a tiny crack in a folded-over brake pipe which took a while to find. Symptoms were a decent first application of the brake on the backup electrical and then no assistance whatsoever until it had reset. On phone so can't post links but it's a common problem along with the brake light switch and the plenum drains causing the servo to rust. Good luck.

bcmf · 09-05-2014 8:46pm

something similar happened me last year on my A4 AWX. Brakes fine and then nothing. Long story short I changed ALL THE HOSES linked with the vacuum system to silicon hoses. Huge difference straight away.
If you pm your email I will take a picture tomorrow and show you.

ION08 · 12-05-2014 6:23pm

Ok, so I left the car with my trusted mechanic on Sunday. He took off the wheel while I was there and tried to bleed the brakes (me pumping the pedal) but there was no brake fluid coming (topped up with DOT4 fluid beforehand)

As such, he diagnosed a faulty Brake Master Cylinder.

He got the part for me and fitted it today (€120+€60)

Now he calls me to tell me theere is so much force from the brakes that the car wont move as the brakes aren't releasing!

He said he will have another look tomorrow.

Any ideas what could be going on here!?

I hope im not facing much more cost to sort this

bcmf · 12-05-2014 6:40pm

Initally what led me to the hoses was that the brakes were giving a different feel at different times during the same journey.
When I brought it to my trusted mecchy he initally thought master cylinder.
he did few tests and found that there was ,from what I remember, he called a banjo pump. I think its linked to the fuel system as well the brakes. He found the pipe on that that was links to the brakes was slghtly loose.This banjo pump is located right at the back of the engine between the engine and firewall.

He fixed that but the problem didnt fully go away. I then change all the hoses on the vacuum system to silicon ones and the brakes returned to normal.
HTH

sandydan · 12-05-2014 6:45pm

could it be a perished hose that's collapsed internally ,so brake fluid passes beyond collapse point but unable to return, but i would still consider it to be valve problem related to master cylinder and servo unit

ION08 · 12-05-2014 6:46pm

bcmf wrote: »

Initally what led me to the hoses was that the brakes were giving a different feel at different times during the same journey.
When I brought it to my trusted mecchy he initally thought master cylinder.
he did few tests and found that there was ,from what I remember, he called a banjo pump. I think its linked to the fuel system as well the brakes. He found the pipe on that that was links to the brakes was slghtly loose.This banjo pump is located right at the back of the engine between the engine and firewall.

He fixed that but the problem didnt fully go away. I then change all the hoses on the vacuum system to silicon ones and the brakes returned to normal.
HTH

Hmmm, thanks for this.

I actually changes the brake lines when i initially imported the car on the basis of an nct advisory but there may be other "hoses" that might still need looking at.

I will ask him to take a look at these tomorrow.

Thanks

bcmf · 12-05-2014 6:53pm

I took the view that it could be one of a number of hoses so just did a clean sweep and bought 2 metres of silcone hose from ebay and did a clean sweep including the hoses to and from turbo and egr as these are all part of the vacuum system.
My symptoms were, on the same journey, the brakes going from like standing on a wet sponge to standing on a brick.

Crap Brakes! [02 Audi A4 B6]

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