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hijamie
17-04-2009, 01:44 AM
hi, vw passat 02 brake problems, when you hold pressure on the pedal it goes all the way in, have changed master cyl, vacum pump, abs pump. brakes are sharp. bled with machine and manually. check all calipers, have run out of ideas. any suggestion appricated.

Has the abs pump to be recoded if disconnected and reconnected, my abs light is on since i tried another pump vw passat 02

cazyp
17-04-2009, 09:20 AM
Are you saying with your engine running, you pump your brakes pedal to the 'hard' point and then it slowly sinks all the way to the floor with your foot still pressed on it?

hijamie
17-04-2009, 06:09 PM
Are you saying with your engine running, you pump your brakes pedal to the 'hard' point and then it slowly sinks all the way to the floor with your foot still pressed on it?


The engine is running, braking as normal, brakes are good but without pumping and appling steady pressure on the pedal it goes in slowly. even with a pump the pedal still goes in. With the engine off and the air pumped out of the servo the pedal is hard and holds firm until you start engine then it goes in again. It was suggested today that a valve in the servo could be the problem. There would be no point where the pedal is rock solid with the engine running. This car has a duel servo unit and they did have a recall for replacement servos due to water contamation.

afire
25-05-2009, 10:37 PM
Hi did you find out what the problem was having a simalar problem here

Metalflakedave
25-05-2009, 11:20 PM
The engine is running, braking as normal, brakes are good but without pumping and appling steady pressure on the pedal it goes in slowly. even with a pump the pedal still goes in. With the engine off and the air pumped out of the servo the pedal is hard and holds firm until you start engine then it goes in again. It was suggested today that a valve in the servo could be the problem. There would be no point where the pedal is rock solid with the engine running. This car has a duel servo unit and they did have a recall for replacement servos due to water contamation.

Both our Passat TDI SE's do this. I am sure they all do it. Every Passat i have ever driven does exactly this!! They both go right down to the floor slowly as you hold pressure on. The servo severely assists the brake pedal. If the brakes work well and they pump up properly then what is the problem? As long as there are no leaks, I'd leave it alone.

johnmikeh
25-05-2009, 11:53 PM
I have the same problem with my 01 Bora tdi, rock solid pedal with engine off,as soon as the servo comes in the pedal goes half way down then slowly sinks.
Seems like this question has been asked many times.
My worry is that it will be an MOT failure (which is on its way for me soon)
I've read horror stories about people changing every part of the braking system for this problem without a cure. If its such a common problem surely someone out there has the answer.

snapdragon
26-05-2009, 10:11 AM
Mine doesn't go down to the floor but has always felt a bit 'elastic' and spongy.
I just changed the front discs and pads (as I have before) but this time I also changed the front rubber brake hoses. The feel of the brakes is totally transformed, it's like driving someone else's car brake wise.
The hoses looked in excellent condition, but maybe they were swelling/ballooning when the brakes were pressed.

I have the 16" wheel brakes and the ATE Discs were £80 a pair. from Eurocarparts, the pads are EBC Ultimax £21 from buypartby.com
The hoses were from eurocarparts, about £19 a pair.

Of course with doing pads, discs and hoses at the same time, it's impossible to say which made the difference, but I have done the pads before without any improvement.

Next time I work on the rears, I will probably do their hoses too.

johnmikeh
26-05-2009, 05:48 PM
Thanks snapdragon,something to think about and not to expensive for once! lol

afire
26-05-2009, 08:11 PM
Hi its not a soft feel the brakes work well but if you stand on the pedal to slow the pedal depresses much to far its very unerving

hijamie
27-05-2009, 01:59 AM
hi all, many thanx for the replies and ideas, an update to what I have done. As already listed I changed master cylinders, vacum pump, abs pump, and servo, clamped all flexibles, none of these made any difference. The brake have 100% stopping power but on continous pedal pressure it travels in. It was up for test and was turned down although it passed 100% on rollers.
What I did last seems to have inproved the distance the pedal travels which was, A friend suggusted that I pump all fluid out of the system and than hook up a bleeding machine that I use and bleed them again, when doing this I took a notion that the front flexibles felt soft, although I had previously clamped them on test the circuit, these are not expensive so I fitted 2. The new ones felt really firm on comparision. The pedal still travels in but not as far and was accepted in MOT last week. I also talked to a vw master technican who said that all passat, jettas, golfs do this.
One other point on abs, once you disconnect the pump it has to be recoded as it loses the code and must be done on the proper machine. The hand held ones can not code this. I have read that heavy braking will put the light out but I do not think this to be right. Hope this has been of help to some. good luck, happy vw motoring. great cars

johnmikeh
28-05-2009, 07:25 AM
Hi guy's,like hijamie said,it IS an MOT failure,even if they do go firm eventually,excessive travel is an MOT failure.
Mine are exactly as you describe afire,under slow steady pressure they sink almost to the floor.
My feelings are that if it was a component failure somewhere in the system,ie seals,the pedal would keep travelling till you lose braking all together.
I don't think the ABS can cause this as it only comes into play when needed,it sounds more like air,or,as hijamie said,the hoses are swelling under pressure and the brakes dont firm up till that is overcome.
Looks like the best way forward is to changes all 4 flexi hoses then have the system bled under pressure (at least its the cheapest option).

martin1810
28-05-2009, 09:47 AM
Try putting the handbrake on and then pressing the brake pedal. It might not sink as much. The pedal sink is often due to the take up of mechanical play in the system and putting the handbrake on removes half of this.

audijay73
29-11-2009, 01:22 AM
im having the same isues but mines a 80 tdi i first thought it was the master cylinder but after 3 from scrapers i am getting a bit miffed the car had previously been stood for about 9 months and i just thought the ones from scrappys were nakered but i dont think it is but i have noticed working back fom the servo there is a pipe that leads to some thing that looks like a pump or something to asist the servo is it worth a trip to the scrappys or am i missing something simple by the way the pedal only sinks when engine is running

caldirun
29-11-2009, 10:34 AM
The engine is running, braking as normal, brakes are good but without pumping and appling steady pressure on the pedal it goes in slowly. even with a pump the pedal still goes in. With the engine off and the air pumped out of the servo the pedal is hard and holds firm until you start engine then it goes in again. It was suggested today that a valve in the servo could be the problem. There would be no point where the pedal is rock solid with the engine running. This car has a duel servo unit and they did have a recall for replacement servos due to water contamation.
This sounds like normal servo operation.

hijamie
30-11-2009, 12:52 AM
hi, I eventually cured my Passat sport tdi after a tiresome treck. I had replace the master cylinder 3 times, the servo, the abs unit (as you call a pump) to no avail. I replaced the 4 flexible hoses which did not show any fault but on comparison to new ones they were soft. The problem was cured. Warning if you disconnect the abs unit you will have to have it reprogramed by computer. On a vehicle that has been standing i would also strip calipers and make sure the pistons move freely, lubricate with brake fluid -not oil as this destroys rubber seals.
You could also buy a one man bleeder kit, great job. good luck;)