Can anyone help?I have a major brake problem with an Octavia at the moment which arose after another garage had changed the brake fluid using a pressure bleeder which they allowed to run dry!They then re-bled the brakes until they had a good pedal. Then they test drove it & scared themselves! The car then turned up on a transporter.The brakes work fine 9 times out of 10 if used lightly, but if you stand on the brakes the pedal goes rock hard(as if someone has slid a brick under the pedal, not cut the servo pipe)& the car keeps moving. However hard you (literally)stand on the brakes the car does not stop.The brakes have been bled from all 4 corners using the romess pressure bleeder & I have bled the brakes using basic settings on 5051(to initiate the solenoids in the valve block). I then replaced the master cylinder & re-bled the brakes both ways, all to no avail.I then disconnected an ABS sensor to knock the ABS pump out of the equation but the problem persists.I'm certain that this is not servo related because I drive a 1964 Land Rover so I know all about stopping cars without a servo & how they feel. Also, why would running the system dry cause this? Incidentally there is excellent vaccum from the pump. P.s the car is a 2002 ASV it has teves mk 60 brakes with no pressure sensor in the master cylinder.

PLEASE HELP

Just a thought - do you know if they adjusted the rod from the cylinder to the servo - I have seen that before - also if you have bled using 5051 for basic you should be clear - any faults in the ABS system ?? -- does the ABS work normally when the fault is not apparent ?

try clamping off each corner or front and back Separately and see if the pedal improves. ive had problem with air trapped in the rear pipes. is it disc brakes or drum.

ade

try clamping off each corner or front and back Separately and see if the pedal improves. ive had problem with air trapped in the rear pipes. is it disc brakes or drum.

ade

Using the VAG5051 diagnostic tool in base settings should erradicate any chance of air as it allows fluid through all solenoids and therefore throughout the whole system.

This problem shows how important the correct equiptment and use of that equiptment is. Where vehicles are fitted with ABS they should only be bled by a pressure fed bleeder and whilst connected to 5051 or similar.

i work in a skoda dealer and ive never had to connect up to 5051 to bleed brakes we just use brake bleeder. where the air was trapped was in the rear flexible hose going to the rear discs. hope tis helps. but it does sound strange how it only happens 1 in every 10 times. try braking hard if brakes are poor quickly pump the pedal hard to see what happens??

i work in a skoda dealer and ive never had to connect up to 5051 to bleed brakes we just use brake bleeder. where the air was trapped was in the rear flexible hose going to the rear discs. hope tis helps. but it does sound strange how it only happens 1 in every 10 times. try braking hard if brakes are poor quickly pump the pedal hard to see what happens??

I work in an Audi Dealer -- and neither do we(most of the time) - but you are supposed to connect to 5051 to fully bleed an ABS equipped car, I must admit we only ever do it if there is a problem,using the correct type of bleeder and not allowing the resevour to empty erradicate the need.

I work in an Audi Dealer -- and neither do we(most of the time) - but you are supposed [/i'] to connect to 5051 to fully bleed an ABS equipped car, I must admit we only ever do it if there is a problem,using the correct type of bleeder and not allowing the resevour to empty erradicate the need.

First of all, thanks for your replies guys. Generally when I bleed brakes, I just use the Romess unit too. But in the running gear manual it says to evacuate the air from the hydraulic unit completely you must use 5051 in basic settings to actuate the solenoids in the valve block. I'm fairly certain that there is no air in this system at all,after putting 8 litres of VAG brake fluid through the car this afternoon I stopped counting.Also the brakes are fine most of the time(9 times out of 10 is only a generalisation though, it could occur 1 time in 20 or 5 times out of 6,there is no rhyme or reason).

The car is an Elegance estate,therefore it has disc brakes to the rear. If you pump the brake pedal rapidly when the problem happens, nothing changes. It still feels like you are stamping your foot on a concrete floor as you continue approaching obstacles as rapidly as you did before pressing the brake!

I don't think the other guys adjusted the push rod between the servo & the cylinder because;A I think they are scared of anything more than an oil change & B When I changed the master cylinder everything looked Virgin. Although I will check the push rod Tomorrow afternoon.

I haven't tried clamping off pipes individually. I don't personally think this is a blockage because during bleeding fluid ****es out of all 4 bleed nipples, & no single brake shows a high temperature on the infra-red thermometer. I will however also give this a shot Tomorrow.

Last of all the ABS & ASR are fine when the problem is not apparent. With the ABS sensor disconnected this afternoon I could lock the brakes absolutely no problem (unless the problem appeared). I was naturally unable to lock the brakes with the ABS connected.

P.s there are no faults in any memories.

to me it sounds like something is getting jammed against something. Make sure nothing has fallen down the back of the engine and is jamming against the pushrod, also check that nothing has been disturbed or loose that is perhaps only making intermittent contact.

Also, check the brake pedal area in the car where it is attached in the footwell to make sure nothing is fouling in that area.

I couldn't see anything that physically would foul in the engine bay or in the footwell area. When I changed the master cylinder,initially the pedal went to the floor(indicating 90% that there is no obstacle). Also when bleeding using basic settings, the pedal goes up & down as it should when the abs pump is actuated.I will however double check these. Thanks.

Totally different car some years ago. Same problem. Ford Granada. brakes worked fine in normal gentle driving but if you had to brake sharp, no matter what speed the brake pedal went solid and the car carried on no matter how hard you pushed. Release pressure and brake normally it would brake fine. Solution by ford was a new abs system. Incidently the Ford computer remembered the faults in its memory. We had several Granadas and several of them were affected. The sensation is like the abs cuts in, releases brake pressure but then fails to re apply the effort

Geoff

this is interesting! seems like an abs problem then, is there any known way to solve it? (I'm glad I don't have abs on my fabia now )

hmm, actually I have...