Brake pedal travel ..... to the floor......

[WheelerDave 10]

Interested if anyone has any ideas....or if it could just be air...

 

The brake pedal goes about half way down and the brakes work, but not full strength. Then if you push harder on the brake pedal you can force it to the floor, brakes still not full strength.

 

If you pump the brakes a few times everything is normal - pedal goes half way down and brakes feel fine. However, after a short period of time the symptoms above come back.

 

It's kind of worrying when it first happened, but I think it's always done it a bit.

 

It has a refurbished abs pump and the abs works, but the light seems to stay on sometimes but I have not bottomed that out yet. Could just be lack of use as the car had not been driven much for over a year.

 

It's a 1992 Corrado VR6.

 

Any thoughts welcome?

[southerner88 10]

My Friend's BMW 3 series had a similar problem, he eventually checked the brake fluid. The fluid was pretty much black which we found out to be because water had got in. We drained the fluid out, topped up and bled the system and all seems much better now, although he still doesn't know how water got in.

[seanl82 23]

His missus probably topped it up with water thinking it was the screen wash reservoir! :lol:

[southerner88 10]

His missus probably topped it up with water thinking it was the screen wash reservoir! :lol:

 

:thumbleft: unfortunately, that is very possible!

[VW_OwneR_85 2]

idd check for leaks around any of the brake pipes, if your not loosing any fluid and you don't find any leaks and you have bled it with new fluid then check out the master cylinder , don't think theres any easy way to test them

[WheelerDave 10]

Thanks guys. I have checked and there are no leaks. I have also bled the systems and there is no major air in there and the fluid is in good shape, so it does look like a master cylinder problem to me (seals failing?).....ouch.....

 

This is what I had feared it might be, but was hoping someone would tell me I was missing something unique to Corrados

 

Where can you get new master cylinders from?

 

Thanks for the replies guys, much appreciated.

[southerner88 10]

Which car and year? I have a working one from a late vr

 

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[WheelerDave 10]

Thanks. It's a 92 k Reg, so presumably an early one?

 

I've just read the forum posts about recon at pastparts.co.uk so will probably go for that next it think as only £120. Seems like a safe route to me, given its the brakes!!!

[Dox 23]

They are a swine to bleed especially if they've been completely drained to replace the pump.

 

What method have you used to bleed the system? pressure bleeder or two man method?

 

Did you force open the rear compensation valve on the rear axle?

 

Did you bleed off the nipples on the master cylinder and the abs pump?

[WheelerDave 10]

I didn't do a full bleed, but is was all fitted properly (I think).

 

The thing that is so strange is the way the pressure just disappears slightly randomly. Also the way the pedal can be pushed half way down then forced to the floor if you push a bit harder. It all feels more like a leak or a seal failing than just air in the system.

 

I could very easily be wrong though????

[WheelerDave 10]

Sorry, to answer the question, I used the air pressure 1 man bleeder to bleed the system....

 

I only did the brake calipers and not the abs or master cylinder as it all seemed okay

[Dox 23]

I bled around 3L through mine, 3 times at each corner with the compensation valve forced open (without it the pressure to the rears is reduced). Even then the pedal wasn't great for the first 100 miles or so - it was low but never went to the floor.

[VW_OwneR_85 2]

master cylinder seals may have failed from bleeding when the pump was replaced, bleeding an old system can have negative effects on old seals, you got to think that most of these parts are pretty damn old now {24 years?!}, I had to replace my clutch master cylinder last year after I replaced the flexy hose on the gearbox as it kept randomly staying down if I stayed on it for a short amount of time,

 

also someone mentioned black brake fluid earlier , I was under the impression that blackness was because of wear from rubber parts seals flexys etc etc?, I remember when my friend brought a mk1 golf and did his brakes with new pads and fluid, his fluid was black!! immediately thought of rubber seals, his brakes were fine though,

[WheelerDave 10]

Just to close this one off, I had the brake master cylinder referred by pastparts.co.uk. Great job and very good price.

 

System then bled with a one man bleed kit and all fine now.

[Cressa 44]

Glad you got it sorted. As this sounds 100% the same problem I have, I'm going to go down this route

 

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[WheelerDave 10]

The only thing I did come across when I put it all back together was the pipes to the abs unit (think ones) had been put on that wrong way. They were crossed over so the top one was fittest to the bottom of the reservoir and the bottom one to the top. Quite how this had been done I don't know! Doubt this was anything to do with it but thought I would mention it.

[Cressa 44]

Thanks. I'll bare it on mind when I get to take mine off. Hopefully soon when I've re-sorted my suspension out to get to the engine. I do always take photos of a before and after to ensure things go back as they were. Although that's not much use if refitting back into a wrong position I suppose. Well done in sorting yours

 

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