Brake pedal goes to floor randomly, no leaks, no air, brakes work fine otherwise

**Lozzy90** · 30-01-2017,07:30 PM

Thanks for the advice people. I have purchased another MC but have yet to swap it, I'll try and re bleed the whole system again before I fit it as Im also not convinced it is the MC. I changed the front pads today as again the previous owner somehow has two different pad brands fitted to either side, and either side both with different levels of wear. So have fitted new pads to both sides today, will hopefully bleed everything again within the next few days weather depending.

I have got a pressure bleeder, right thinking you only need around 10psi for it?

Update: Having driven it about 10 miles sinxe working in it today it hasn't yet occured, so fingers crossed it won't happen again and it was just the front calipers being funny or something. Will update if it does and if/how I solved it.

Once again thanks 👍

**Col** · 31-01-2017,02:24 PM

Well, that was unexpected !

When new pads are fitted, especially on old discs, the pedal can feel wooly for quite a while until they have bedded in.

Keep us updated.

**niall campbell** · 31-01-2017,02:38 PM

you could run the engine to bleed the brakes also if your having problems bleeding, only had to do it once right enough

**Col** · 31-01-2017,04:01 PM

Originally Posted by niall campbell

you could run the engine to bleed the brakes also if your having problems bleeding, only had to do it once right enough

What do you mean? You cannot bleed brakes by running the engine.

Back to the OP...

Judging the garage / previous owner by the fact that there were two different sets of pads on the car and the fact they changed a hose or two further re-enforces the fact that it is most likely a bleeding issue. That said and from the "quality" of the previous work carried out, it could quite easily be that the master cylinder seals have been turned inside out!

On any other car, I'd say and continue to say as I have that it is likely to be bad bleeding but on this one one, it is anyones guess.

Lozzy, I do hope it is sorted, but keep a real close eye on things!

**Lozzy90** · 31-01-2017,08:04 PM

Thanks for the advice Col, have driven the car around today and the pedal hasn't sunk down, as you said the brakes do feel odd but for the moment I'm putting that down to the new pads on old discs. The discs did look in good condition and don't feel/sound warped so hopefully the pads will settle in ok.

Also found out today I have a relative who can get me a TRW master cylinder for cheap as the place he works for owns TRW (and my car uses TRW not ATE) so for now I will return the MC I purchased back to the motor factors.

Will keep the thread updated 👍

**Lozzy90** · 28-05-2017,05:55 PM

Alas! The problem has returned.

Same as before, only slow speeds, pedal will sink right to the floor with light pressure applied to the brake pedal. It seems to happen ALOT more in warmer weather making me reconsider if it is indeed a faulty Master Cylinder. I'm now thinking what was said earlier in this thread about a rubber line having been clamped and ballooning? But when it get's warmer it can balloon more easily?

Braking while slowly rolling down a hill is a real pain at the moment due to this hot weather. The initial pedal press is fine, but when you then apply slight pressure to just keep the car rolling at let's say, 2 - 3 mph the pedal just slowly sinks and the car keeps rolling. To stop this I either have to press much harder, or release the pedal and press again, then the car will stop completely. This just does not feel like a master cylinder problem. Again as previous, I can press the pedal as hard as I can with the engine off and it will not sink with constant pressure, nor will it sink when the engine is on and I'm not moving or don't let off the initial pedal press.

I'm currently considering replacing the front caliper seals and dust boots, and when I changed the pads a few months back the dust covers had small tears in them and the groove they sit in was covered with crud and corrosion.

Thoughts on this?

Thanks in advance.
Lozzy.

EDIT: Should also mention I have re-bled the brakes over the last few months and cycled the ABS pump as I have access to VCDS.

**Lozzy90** · 01-06-2017,10:40 PM

Update to my problem. Today I bled the front offside caliper with a vacuum bleeder, and had continuous bubbles coming out however when I then pressed the brake pedal clear fluid with no bubbles came out, could this be a faulty caliper seal? And could that cause the problem Ive got?

Another thing I noticed is that my front calipers use metal clips and say ATE on them however my brake res says Lucas on it. As far as I'm aware these cars use either ATE or Lucas all round. Any ideas?

Thanks.

**zollaf** · 01-06-2017,10:42 PM

vacuum bleeder will pull air in past the threads on the bleed nipple, unless you remove the nipple and coat the thread in copper grease to form an air tight seal. so no, this is not your problem.

**Lozzy90** · 03-06-2017,08:11 AM

Thanks zollaf that clears that up, so its just the caliper problem now. Ill check the rear calipers to see i lf they are Lucas or ATE when I get chance. If the previous owner has put the wrong calipers on the front would that cause this issue?
Cheers.

**Lozzy90** · 03-06-2017,09:51 AM

Well after some research online I had discovered that from factory these cars came with a mix of ATE and Lucas components so really at a lost now, thought I may have figured out why it's doing this. Really haven't got a clue now I'm getting to the point where I'll start just replacing parts in the hope it fixes the problem but I'd rather avoid wasting time and money doing that if I can. Any resident brake experts on here have any idea?
Cheers, Lozzy.