3 hours ago, Haladams said:

Two very visible nuts hold the master cylinder to the servo - undo them most of the way, prise off the cylinder 10mm,  and put a QTip in the back. If you do not have any leaks at the wheels and your pedal is going down all the way, then the QTip will be probably be wet.  Which means you probably have fluid in the servo. Before you do anything else, the cylinder needs attention, the servo needs cleaning along with the vacuum line BEFORE you move to the next item...

Whitout taking apart the 4 distributor pipes?

26 minutes ago, Zimo said:

Whitout taking apart the 4 distributor pipes?

Just use penetration oil to loosen them up and then carefully unscrew them. 

My second thoughts are to do the job properly - the rest of your brakes are telling a story. This is your life you are playing with so take the cylinder off and either replace it or recondition it. At the same time remove the servo and replace anything that is needed as I imagine it is full of brake fluid.

 

As he says, carefully loosen all the screws of the four pipes and the two holding it to the server. Remove.

 

Here you are - new one at Autodoc, only 17€. Probably cheaper overall than cleaning your old one and putting in new rubbers. 

https://www.autodoc.de/car/9880235

 

 

 

25 minutes ago, Haladams said:

My second thoughts are to do the job properly - the rest of your brakes are telling a story. This is your life you are playing with so take the cylinder off and either replace it or recondition it. At the same time remove the servo and replace anything that is needed as I imagine it is full of brake fluid.

 

As he says, carefully loosen all the screws of the four pipes and the two holding it to the server. Remove.

 

Here you are - new one at Autodoc, only 17€. Probably cheaper overall than cleaning your old one and putting in new rubbers. 

https://www.autodoc.de/car/9880235

 

 

 

Just to undertand the braking system: 

-servo : is the part that amplify the strenght of my foot

-master : is what actually trasform that strenght in braking force by idraulic lines to single wheel. 

Right?

So if my brake brakes even  when the servo  "deflate", why the "faulty" has to be the master?  So the master "transmit" my strenght to the calipers. I mean i dont see leaks from brake calipers, lines .... if the master cylinder would leaking at this moment i have to see a wet serve even from outside and/or a loss of breaking fluid from the reservoir. 

My ingnorance is asking this with my bad english.

On autodoc i found a brembo master for 50€ and will be happy to spend that money on reputable manufacturer, but sadly i am not able to find a servo and the non return valve.

Like always, many thanks

Edited 5 November, 20196 yr by Zimo

11 minutes ago, Zimo said:

My ingnorance is asking this with my bad english.

You said it. Help us to help you.

The English is not a problem! It is the order you are doing things!

 

The master cylinder is the heart of a brake system. Your foot hits the brake pedal that in turn pushes fluid to all four wheels. The servo helps by pushing more pressure. It is dead important to have your master cylinder in perfect condition BEFORE you look at any other bits.

 

What worries me is that you say there are no leaks at the wheels and the fluid level is not falling. Yet your pedal goes all the way down on braking. Either you have a leak somewhere or there is a dreadful amount of air in the lines. But you say the brakes have been bled with a machine. Something not right here.

 

So, start at the beginning. Replace the master cylinder. No need for a Brembo one, a remanufactured CAR one is good to get you going. You will be better off spending money on front caliper requirements which is next to look at after your master cylinder.

 

Before you replace the cylinder, check the servo. I imagine it is full of fluid... If it is, it will need cleaning then checking the diaphragm. And the vacuum pump - but these are later. Do the master cylinder!

 

 

Yes yes yes,
Prioritize things,
First remove master cylinder check for leaks and replace if needed (it will most likely BE needed)
Then check the servo itself look for oil, dot 4 WILL affect different rubber compounds in different ways so check the diaphragm carefully maybe use a foot pump or something to check that it is holding air.
Then procced to the caliper which i bet is fixable although I am not going to state my method as it is not reccomended (although it will sometimes work)
Then comes eveything air related so that be air valves pressure regulators and what have you.

Ok 😒i will do that ..... but no one explained yet

3 hours ago, Haladams said:

What worries me is that you say there are no leaks at the wheels and the fluid level is not falling. Yet your pedal goes all the way down on braking. Either you have a leak somewhere or there is a dreadful amount of air in the lines. But you say the brakes have been bled with a machine. Something not right here.

As I've said previously, the leak is INSIDE master cylinder.

 

Indeed. But an internal leak invariably allows fluid to pass back into the servo on the return stroke, so that at some point it will be noticed that the fluid level falls - albeit a small amount. 

10 hours ago, Haladams said:

Indeed. But an internal leak invariably allows fluid to pass back into the servo on the return stroke, so that at some point it will be noticed that the fluid level falls - albeit a small amount. 

Here , this statement of your made me remind that the low brake level light on dashboard was more present in the last time before the bleeding operation.... 

37 minutes ago, Zimo said:

... the low brake level light on dashboard was more present in the last time before the bleeding operation...

Ummm... so you got used to low brake fluid level alert, except now it is more often... I miss the angry emoticon with the little guy banging his head on a brick wall...

14 hours ago, Zimo said:

Ok 😒i will do that ..... but no one explained yet

Please tell me what to explain and I will do my best

 

1 hour ago, RicardoM said:

Ummm... so you got used to low brake fluid level alert, except now it is more often... I miss the angry emoticon with the little guy banging his head on a brick wall...

I explained some post above..... i mistake the alert for the hand brake light as i took off carpet....and yes i have to check all the alert light on the dash....

 

@Thefeliciahacker explain why if i brake only with me foot strengh(after the servo goes off or the master leaks) the vehicle brake. I was thinking that if the master cylinder leaks , i would have no brake strenght at all.

1 hour ago, Zimo said:

I was thinking that if the master cylinder leaks , i would have no brake strenght at all.

There are leaks and leaks. As there is black and white and a whole lot of grey in between. Very often a fail starts with a small leak that gradually gets worse. Right now the leak might be small and you have "some" brake. But rest assured, if you don't solve the problem now you will have no brakes at all. Your call.

Call me stupid or ignorant but i still dont get it. Maybe i didnt explain the problem right. I'm sorry if you have to explain to a dumbass like me. But i need to understand first.

I did the workshop manual procedure of the picture below and it faild. The manual said to check non return valve, if it works , change the servo.

While driving i have a loss of servo help not braking strenght.  Because while braking , if the pedal sink of certain amuont of travel , if i press more the pedal the pickup brakes and stops.

So sorry to insist on this but ignorance is a bad evil.

As always many thanks for your answers, help and last but not least , patience

Lorenzo

I am pretty sure that you said earlier you hear a 'hiss' from the servo. Maybe I have it wrong for which I apologise.

 

So the servo is no good. OK, no surprise as your whole brake system sounds no good.

 

Quick test: Start the engine and let it run for a minute. Turn the engine off and immediately press the brake pedal three times - what do you feel and hear on each press?

35 minutes ago, Haladams said:

I am pretty sure that you said earlier you hear a 'hiss' from the servo. Maybe I have it wrong for which I apologise.

No no you got it right! I hear a hiss.

Sure this night i will try. Thanks!

4 hours ago, Haladams said:

Quick test: Start the engine and let it run for a minute. Turn the engine off and immediately press the brake pedal three times - what do you feel and hear on each press?

Test done:i can hear the hiss of a normal servo, pedal get harder, and after the 3rd time i remained on the pedal that slowly "deflate".

So that means that the servo(and non return valve) are good and i have a master cylinder leaks? 😅😅😅

Was there an air hiss on the second and third press of the pedal?

 

Now you need to do the same again, but wait a few minutes after turning off the engine and pressing the pedal.

 

Listen - how good do you want this car to be, and what lengths are you prepaired to go?

 

I personally think you should renew pretty well the whole brake system. You have already replaced a wheel cylinder and front brake pads. I think you need to look at replacing: Servo, vacuum valve, master cylinder, exchange both front calipers, replace both caliper slide pins, replace the other rear wheel cylinder and rear linings if necessary. Just my opinion to do the job properly.

 

And your vacuum pump needs checking as well.

 

The most expensive item is the servo. they are up around 200€, but Autodoc do remanufactured ones for 52€ but I see they are out of stock at present. Worth asking them when they are back in stock. It would be good to continue with a new servo and master cylinder, so give it some thought, yes?

 

 

Zimo

It is the way you're describing the faults that bothers us. I don't think you are so ignorant that you can't describe properly. It's that you are not accurate and methodical. A garage mechanic would have shot you by now 😀 You should think letting somebody else do the job for you.

 

My call is you need to do the following in this exact order:

 

Remove the brake master cylinder, disassemble it, inspect the seals.

If you find evidence of bad seals, buy a brake master cylinder repair kit or even better a new brake master cylinder. Install it.  Now the brake pedal sink should be gone.

 

Next, if you find that the braking is not servo assisted (big effort to brake) you have to replace the brake servo booster as a whole.

 

Now get to work!

Ok will do the test.

The car is intend to use as a daily car , on secondary roads so no highway and long trips. So yes new servo and master sounds good. Maybe i can start with new master and after(opefully ) new servo...

3 minutes ago, RicardoM said:

Zimo

It is the way you're describing the faults that bothers us. I don't think you are so ignorant that you can't describe properly. It's that you are not accurate and methodical. A garage mechanic would have shot you by now 😀 You should think letting somebody else do the job for you.

 

My call is you need to do the following in this exact order:

 

Remove the brake master cylinder, disassemble it, inspect the seals.

If you find evidence of bad seals, buy a brake master cylinder repair kit or even better a new brake master cylinder. Install it.  Now the brake pedal sink should be gone.

 

Next, if you find that the braking is not servo assisted (big effort to brake) you have to replace the brake servo booster as a whole.

 

Now get to work!

Yep . I already show the problem to the shop where i made perform brake lines bleeding:  he told me that if after changing the rear drum cylinder and bleeding the circuit the problem continues, the problem is the "pump" . At that moment I took it for granted that he was speaking of the master cylinder without asking further information.  Ask him a price for the part and he ,after a brief search on pc , shoot me (😁😁)that the part cost 100 or 130€ (he had to search the right code for my pickup) . But as i already said on autodoc a brembo master cost around 50€.... and yes i dont trust mechanics no more (at least the ones i found since now). i respect everyones work but i respect my money too😆😂

My suggestion is that it is easier to do both master cylinder and servo together, and once finished, it is easy to progress to the next job. But no problem if you want to do the master cylinder first and come back to the servo if necessary.

 

the parts you need are:

Master cylinder (oen  6U0611019): https://www.autodoc.de/autoteile/oem/6u0611019?search=OEN 6U0611019

Re-manufactured Servo (oen  6U0612107): https://www.autodoc.de/autoteile/oem/6u0612107?search=OEN 6U0612107

 

Personally, I am not a big fan of just replacing master cylinder seals, but if you want to save a few euros, then these are what you need: https://www.autodoc.de/autoteile/reparatursatz-hauptbremszylinder-15088/skoda/felicia/felicia-i-fun-797/8703-1-9-d

 

I see though that Autodoc do not have the servo in stock. Ask them when they expect to have some in stock. Do you have Autodoc or Onlinecarparts in Italy? If so, then worth asking them - quote the original equipment numbers.

 

Before you make the change, do you have a VW garage near you, or a good independant garage (not the person who bled your brakes as he sounds a 'cowboy')? Maybe call in one day and ask them to put a vacuum gauge onto your vacuum pump and check it is ok. This is a ten minute job for someone who knows what they are doing. They could also advise you how the check valve is operating. It may well need a proper clean.

 

 

I used autodoc already and they are also out of non return valve

10 hours ago, Haladams said:

Was there an air hiss on the second and third press of the pedal?

 

Now you need to do the same again, but wait a few minutes after turning off the engine and pressing the pedal.

 

Done the test: the first 2 hiss and make the pedal harder , the 3rd dont hiss.(and if i remain on pedal it sink/deflate)  Pretty the same on the previous test.

This morning i had to use the pickup to bring some wood at  a woodworker and standing still at the stop i pumped the pedal for 3 or 4 times and this made the minimum revs fluctuate. Could help?