Member Since: 03 Nov 2007
Location: Glorious Devon
Posts: 3254
Brake Pedal Sinking to the Floor
I'm hoping that this feature is not going to cause me grief.
Keyless ignition. Get in Disco, press brake pedal (rock solid - no movement). Press the ignition button, engine starts and immediately the brake pedal (if pressure maintained) sinks to the floor slowly. Pumping the pedal brings it back up but as soon as pressure is maintained, back to the floor it goes.
Under way and braking normally, it pulls up quickly and the sink is not noticeable - mainly because the braking period has not been prolonged. However, if, having come to a halt, the pressure is maintained, the pedal goes to the floor.
Is this normal? Is it a feature of keyless ignition/auto box? Never had either before and never experienced anything like it.
Bill WrightNever take life too seriously. Nobody gets out alive anyway.
D4 SDV6 SE Tech Kaikoura Stone MY15.
17th Feb 2010 3:51 pm
DSL Keeper of the wheelie bin
Member Since: 11 May 2006
Location: Off again! :-)
Posts: 72774
Sounds like the brake servo problem carried over from the D3.
17th Feb 2010 4:05 pm
Bill Wright
Member Since: 03 Nov 2007
Location: Glorious Devon
Posts: 3254
On the basis of that DSL, I'm arranging for the dealer to get involved rather than LRA. Cheers
Bill WrightNever take life too seriously. Nobody gets out alive anyway.
D4 SDV6 SE Tech Kaikoura Stone MY15.
17th Feb 2010 5:04 pm
jm105845
Member Since: 21 Aug 2007
Location: dublin
Posts: 271
hi bill
i had a similar issue on my last 06 model and it turned out to be
a broken brake pipe in at the back of engine
however mine was loosing brake fluid
regards
jj
17th Feb 2010 5:14 pm
Bill Wright
Member Since: 03 Nov 2007
Location: Glorious Devon
Posts: 3254
Thanks JJ - no fluid loss that I can see. But I'll keep checking.
Bill WrightNever take life too seriously. Nobody gets out alive anyway.
D4 SDV6 SE Tech Kaikoura Stone MY15.
17th Feb 2010 5:33 pm
carcollector
Member Since: 22 Jan 2010
Location: @ home
Posts: 75
if you are not loosing the fluid, then the master brake cylinder is at fault.
if you are loosing fluid then i suggest you follow the trail of brake fluid to find the culprit.
17th Feb 2010 6:53 pm
Bill Wright
Member Since: 03 Nov 2007
Location: Glorious Devon
Posts: 3254
LRA/AA just been and checked it out. No leaks anywhere. He tried it out and the pedal went to the floor each time but he reckoned it was normal. No cause for alarm then apparently.
If that is the case, I wonder if any D4 owners reading this will check theirs and let me know if it is happening to them just so I can confirm that it is not an isolated case. Thanks.
Bill WrightNever take life too seriously. Nobody gets out alive anyway.
Mine doesn't do it and if it did it would be in the dealers faster that you could say LRA.
Take it in, there is something wrong.
18th Feb 2010 11:51 am
DSL Keeper of the wheelie bin
Member Since: 11 May 2006
Location: Off again! :-)
Posts: 72774
Deffo get it to the stealer, the pedal does not do that!!! Get it there on the back of a recovery truck as some people have had brake failure with those symptoms! If you do drive it there and worst happens keep your left hand close to the EPB switch so you can apply that using its emergency mode.
18th Feb 2010 12:44 pm
dragonfly28
Member Since: 08 Jan 2012
Location: South Coast
Posts: 66
Reviving an old thread, but my 2014 D4 seems to have developed similar symptoms so I'd be interested to hear the outcome of your experience.
After driving home normally last night, when parking on the drive I noticed the pedal sinking if pressed firmly. I've checked the fluid level this morning, so looks unlikely to be a leak.
Time to make a call to LR - what's the odds on a "they all do that sir"?2014 D4 XS
2006 D3 HSE - sold
1999 Defender 110 CSW TD5 - sold
31st Jan 2020 12:03 pm
Bardley
Member Since: 02 May 2018
Location: Hertfordshire
Posts: 439
With no leaks, this is usually the master cylinder seal where fluid passes around the seal, allowing the pedal to sink.
Best advice as above is to not drive the car.
With knowledge of a braking fault, any collision subsequently will pose a few difficult to answer questions given that this is now in the public domain...2011 MY D4 HSE
Previously 2001 D2 TD5, 1996 D1 300Tdi, 1985 90 2.2 petrol.
Bikes! KTM, BMW, British, Classics and others.
31st Jan 2020 12:06 pm
Gareth Site Moderator
Member Since: 07 Dec 2004
Location: Bramhall
Posts: 26699
Are you sure its actually reaching the carpet? My pedal will be solid if i press it with the engine off. The reason is that if you press the brake a couple of times with the engine not running, you exhaust the vacuum in the servo. The fact that the pedal stays solid in this scenario means that there is no leak, externally or internally in the master cylinder.
When you start the engine, you induce vacuum to the servo which multiplies the force applied to the brakes, and the pedal will sink.
31st Jan 2020 12:13 pm
dragonfly28
Member Since: 08 Jan 2012
Location: South Coast
Posts: 66
Thanks for the replies and advice.
The pedal is firm when the engine is off, but when running the pedal will slowly sink through around half the travel under firm pressure and it will do this repeatedly, even if i try to pump it first.
With a long-distance family trip coming up soon, I'm not taking chances.
Luckily it's still under Approved Used warranty, so I called LR Assistance and they're sending someone to investigate this pm. I will let you know what they conclude2014 D4 XS
2006 D3 HSE - sold
1999 Defender 110 CSW TD5 - sold
31st Jan 2020 12:56 pm
L319
Member Since: 14 Dec 2013
Location: Herefordshire
Posts: 2080
My D3 has done this and I was assured by Dealer and two independents it is normal. Pedal totally solid with no Servo action which proves there are no leaks in the hydraulic system. I replaced the servo for another reason and pedal is slightly better, which proves to me that it is the servo creating this soft action.
31st Jan 2020 1:44 pm
dragonfly28
Member Since: 08 Jan 2012
Location: South Coast
Posts: 66
Thanks for your experience too L319.
Land Rover Assistance just left. The engineer's assessment was there is nothing untoward, and that he assured me he would have logged it if he had any doubts. He said that what I am feeling when parked is it "pushing through the servo".
He observed the rear disks are probably getting near replacement, and that this could contribute to a softer pedal. It's due a service soon, so I will do that before my trip.
Also road tested and it's pretty impressive (and reassuring) how quickly it can stop when you really try. Pedal felt fine then too2014 D4 XS
2006 D3 HSE - sold
1999 Defender 110 CSW TD5 - sold
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