Hi all
L322 TD6. Just started to get the brake pedal fade away when you press it. Car stops (say at lights) but pedal slowly creeps to floor whilst holding your foot on it.
Pump it a few times and pedal goes hard (as should) but creeps away again.

No fluid leaks. Can’t hear any vacuum leaking.

Worth trying a pressure bleed? Or are we thinking Master cylinder?

Thanks in advance
Tel Accept, some days your the pigeon, some days your the statue!

Technically, what you're experiencing isn't fade, but pedal "creep".
Assuming you've checked for external leaks & haven't found any, most likely cause is an internal leak in the brake mastercylinder as you've said.
A faint possibility is dirt / debris on 1 of the mastercylinder seal lips.
Its worth trying to apply the pedal hard (engine operating, but car stationary) & then releasing the pedal fast.
This can cause fluid to flow over the seal lip & possibly dislodge the debris if there is any thats not embedded in the lip..
Its not guaranteed to work, but it might. Paul,
2001 Discovery 2 TD5, 211,000 miles & climbing
2006 FFRR TDV8 Vogue 151,000 miles & now sold
Member of Midland (Land) Rover Owners Club, www.mroc.co.uk

Thanks so much.

I’d normally go straight to Master cylinder, but I don’t know much about these “brake booster” units that’s apparently fitted?
Not sure what issues they can create.

Thanks. I’ll try your suggestion in morn and reply. Thank you. Accept, some days your the pigeon, some days your the statue!

You have a leak somewhere…. Had similar when my rear brake pipe split…. Pedal went further than normal, which then stuffed the seals in the master cylinder as the piston had not gone that far before and garage thought there might me some type of “rust lip” or similar inside it…. As mentioned above.

 2011 Range Rover Vogue SE 4.4 TDV8

Previous cars :
2003 Range Rover Vogue TD6
1999 Discovery Td5 ES
1995 BMW M5 3.8 6 speed
1992 Range Rover 3.9 Efi Vogue
1992 BMW M5 3.8
1988 BMW 735i SE
1989 Ford Sierra XR4x4 2.9i
1981 Ford Fiesta Supersport

Last edited by mjdronfield on 1st May 2022 6:25pm. Edited 1 time in total

I stamped on brakes some 2 month ago and it burst a rusty pipe. I replaced pipe (front to rear). Bled all up and has been fine for last couple months.

Now this pedal fade. Not loosing fluid and can’t find any leaks. Accept, some days your the pigeon, some days your the statue!

Ah, ok. I stamped on the brakes when mine split.

Not sure then mate… I assume the brake fluid level is constant?

Did you put the ABS module in to “bleed” mode?

Must have air in then…. Maybe worked it’s way out….

 2011 Range Rover Vogue SE 4.4 TDV8

Previous cars :
2003 Range Rover Vogue TD6
1999 Discovery Td5 ES
1995 BMW M5 3.8 6 speed
1992 Range Rover 3.9 Efi Vogue
1992 BMW M5 3.8
1988 BMW 735i SE
1989 Ford Sierra XR4x4 2.9i
1981 Ford Fiesta Supersport

Boydonegood wrote:

Hi all
L322 TD6. Just started to get the brake pedal fade away when you press it. Car stops (say at lights) but pedal slowly creeps to floor whilst holding your foot on it.
Pump it a few times and pedal goes hard (as should) but creeps away again.

No fluid leaks. Can’t hear any vacuum leaking.

Worth trying a pressure bleed? Or are we thinking Master cylinder?

Thanks in advance
Tel

Thanks so much guys

So update on a new day!
Servo is working. Stand on pedal, start car and pedal drops an inch and holds.
No fluid loss or vacuum leaks.
Stamped on the pedal a few times and “maybe” cleared a bit of dirt in cylinder as suggested?

Car drives and brakes put you through windscreen. Seems random if the pedal slowly drops away under pressure (at lights etc) or not now.

Will run it for a few days and see. Maybe just me as I have been driving a few different cars lately.

If not happy I think I’ll throw a master cylinder on.
Is it just brake pipes and bolted to servo? Or is the “plunger” for the master cylinder connected inside servo?
Cheers again your stars as always.

Tel Accept, some days your the pigeon, some days your the statue!

It’s caused by fluid leaking past the seals, it doesn’t leak out if the brake system, just bypasses back to the resovoir. BMW i3 Electric Car
2012 Full Fat RR 4.4 TDV8 (now gone)
2006 VW Touareg 3.0 TDi V6

Yeah it done it to me driving home just after my last post.
Braking to turn a corner and pedal started to creep away under foot.

Will look for a master cylinder or seal kit today and park it up until next weekend.
Seems 1 min it’s holding. Next month it’s letting the fluid passes the seals. Accept, some days your the pigeon, some days your the statue!