182 soft brake pedal.

[MRBILLYUK]

As per title. About 5 weeks ago the brake pedal suddenly became soft/ long travel.
So I bled the brakes , just a bit of air came out and the pedal was solid again for 2 weeks. Then it went soft again and the pedal travel was almost to the floor.

So I bled the brakes again. Again the pedal was solid, the servos working as it should. I was out in the car today , everything was fine then tonight I'm back to having a soft pedal and long travel.
I've been doing a bit of reading. Some things point to the master cylinder?

Surely if the master cylinder was knackered I wouldn't have had good braking for the last 3 week's then suddenly go soft again?

Any ideas anybody?

 

[White16valver]

Is it still (mostly) old fluid? IIRC it absorbs water over time, so perhaps it is somehow taking some in from the crap weather we're having??

A rapid change from fine to not-fine does point to something else, though!

Do you lose fluid from the system between bleeds (i.e. the reservoir goes down)?

 

[JamesBryan]

Get it bled by someone that can activate the abs pump to get rid of any air in the system.

 

[incy-spider]

Get it bled by someone that can activate the abs pump to get rid of any air in the system.

This 100%


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[botfch]

If you haven't got any leaks then a seized rear caliper can also cause this.

 

[Usr117063]

Same thing for me on non abs cup setup

 

[MRBILLYUK]

It's mostly new fluid now. It seems strange how it was fine for 2 weeks then suddenly became soft with a long pedal travel then when I bled it again it was fine for 3 weeks then a soft pedal again.
I've been trying to find some gravel to activate the abs like I've seen people suggest in other posts I've read but I can't find any.
I haven't lost any fluid between bleeding either. The reservoir is always up to the max mark.
If it stops raining some time over the next few days I'll check all the calipers to see if any are seized and rebleed.
I don't know anyone round here or if any of the garages can activate the abs.
Do you guys reckon my problem could be master cylinder related?
Thanks for the replies with suggestions

 

[JamesBryan]

It could well be a MC issue, but without ruling out air in the abs it's hard to say.

How much fluid have you bled through would you say? Need to do a least a litre really.

 

[MRBILLYUK]

Bled through about 500ml. It was the old ATE super blue stuff coming out at the beginning so I could tell with the colour change the new fluid was coming through.
It might be worth another good bled with alot more fluid ?
I'm hoping it's not the MC. Can air get into the and system even if I've never let the level go low when I bleed it. I've always done it the old fashioned way, a bit of tune with a 1 way valve , pedal down then up .....................

 

[JamesBryan]

Bled through about 500ml. It was the old ATE super blue stuff coming out at the beginning so I could tell with the colour change the new fluid was coming through.
It might be worth another good bled with alot more fluid ?
I'm hoping it's not the MC. Can air get into the and system even if I've never let the level go low when I bleed it. I've always done it the old fashioned way, a bit of tune with a 1 way valve , pedal down then up .....................

Technically yeah, as the fluid absorbs water if it's ever got hot it'll create air bubbles.

Plus it's 15 years old, air will get in somewhere eventually 😂

 

[Usr117063]

I've been trying to find some gravel to activate the abs like I've seen people suggest in other posts I've read but I can't find any.

Just fire it up on the road, its raining even better, can do it outside your house if you really want

 

[MRBILLYUK]

Just fire it up on the road, its raining even better, can do it outside your house if you really want

I've tried so many times today even on wet roads , braking hard. The only time I've had a hint of the abs kicking in is when i brake hard and it's over a manhole cover.
I'll bleed through a litre over the weekend and check all the caliper aren't seized. Fingers crossed it won't be raining.

 

[JamesBryan]

Just fire it up on the road, its raining even better, can do it outside your house if you really want

Yeah it's quite easy to get it to kick in on the road in the wet.

Dip the clutch or shift to neutral while braking heaving, it stops you getting engine braking then which would normally reduce the chance of locking up and allows it to stop the driveshafts easier... in my experience anyway.

 

[Usr117063]

I dont remember the abs not being able to fire on oem calipers when I had them, Ive since having no abs and brembos had the oem calipers back on and no abs and could easily lock the wheels so shouldnt be a problem. I remember the ds1.11 with abs was comical how easy it stopped!

 

[MRBILLYUK]

Had a bit of Man flu over the weekend so never managed to have a look at my brakes.
I've found a nice cobbled back street to fire the abs, done it 20 odd times this morning.
I've bled through 1 litre of brake fluid , so that's about 1.5 litres in the past few weeks.
They all ran clear except the front right which had a few tiny bubbles in one pump of the pedal.
The pedal is rock solid again, like it was both times I bled it before in the past 5 or 6 weeks.
I'll just have to wait and see if the soft pedal and long travel returns like it did the two times previously. Fingers crossed.