A6 intermittent lack of full brakes

[Steve Q]

As the total says really. My a6 has developed an intermittent brake issue. When I apply the brakes the pedal goes nearly to the floor. It's almost as if there is low pressure. 

Iv never lost the brakes completely they're just not responding as normal sometimes. 

The brake discs and pads are fine

no brake fluid leaking and brake fluid was blead and changed in March. 

My local garage is wondering if it's the abs pump but has anyone got any ideas? 

Im currently doing Russian roulette ATM as I never know when it's going to happen! 

[niedzial1983]

Im no expert but on idle pump the pedal and step on the brake hard.

If the pedal went soft, I would suspect a leak in the system. If they pedal didn't go soft after pumping, it might be a bad master cylinder or brake booster

[Steve Q]

Thanks for the reply :) 

what's even more bizarre is that there have been no warning lights on the dash when it happens. 

[Magnet]

Hello Steve,

Check the brake flexible hoses for ballooning when an assistant presses hard on the pedal. Inspect carefully for any slight increase in diameter. Worth checking the simple things first! 

Kind regards,

Gareth.

[Envy]

Check the servo first - diaphragm perforated? 

[Trevor]

Hi Steve,

I would say that each of the responses are possibilities and ones that need investigating individually.

I have come across this sort of fault before and apart from the obvious brake fluid boiling and leaving an air pocket, there are other areas to look at as well.

Hoses, Servo, ABS (bleed fluid from the unions on the modulator block as this never gets replaced unless the ABS invokes), calipers, stuck pads in carrier, stuck caliper sliders, and probably a whole host of other areas but I would go through those first. Maybe the pads are the easiest to remove, clean and refit but if you have to prise any out then there's your problem.

Good luck and let us know how you get on mate, if we don't hear from you then.... (only joking!)

Cheers,  Trevor

[Steve Q]

Thanks all for your help :) 

it couldn't have come at a worse time to be honest. As I'm due to take the a6 to Belgium to see my sister who has just moved there! 

the a6 will be with the garage for a while I think! 

Its really annoying as it's only done it twice in the last 2 weeks. But that's twice too many! 

[Trevor]

It wouldn't take too long to check the brake pads especially if you chuck it into a local garage for them to do the job

[Steve Q]

Iv got her booked in to the garage, and have put the Belgium road trip back a week or so 

[Trevor]

What's the outcome Steve?

[Steve Q]

Still in the garage Trevor :/ so I have no news yet unfortunately :/

[Steve Q]

Update

garage couldn't find anything mechanically wrong with the a6. They suspect that when they did the brake fluid change in March that air may have got into the system. 

So after a second brake fluid change the brakes are working fine now! Fingers crossed it's all sorted and I can go to Belgium with peace of mind! 

Thanks for all your help all :) 

[Dan3222]

I missed this thread completely. I had exact same symptoms on my old Scirocco. First thought it was flexi pipes ballooning out occasionally. I changed them and thought it was sorted about 4 weeks later it happened again. I changed the servo with second hand one. Never did it again.

Just be mindful of it still though mate. If it does do it again while driving do a quick pump of brakes rather than just keep pushing down if that makes sense. 

[Steve Q]

Thanks Dan, dont worry I will be keeping an eye on it. 

If it happens again I think il have to have the servo or abs module replaced. 

Thanks for your advice :) 

cheers

steve

[Dan3222]

No problem,

Have a great trip Mr Q.

[Steve Q]

3 hours ago, Dan3222 said:

No problem,

Have a great trip Mr Q.

Thanks Dan :) 

il do a full report when I return :)