Hi All,

Got a strange issue with the TDV8 which I have only just bought! (Its not even on the road yet! )

I noticed over the weekend when I started it that the brake pedal slowly travels to the floor (under normal pressure). If I really push on it, it will reach the floor in less than 5 seconds

The pedal returns back to normal after a couple of pumps, but again if I leave pressure on the pedal it sinks to the floor.

I have repeatedly pressed the pedal all the way to the floor thinking that there must be a brake fluid leak somewhere, but I've looked all over and cant see anything. Also the fluid level hasn't dropped.

I'm now thinking that this must be the master cylinder? Anyone think the same?

How common is MC failure? And I assume pedal sinking is a symptom of a failing MC? Car has done 115k miles - so not exactly high IMO.

Are seal rebuild kits available for these, or is the only option fitting a new MC unit? (or possibly a good used one?)

Cheers
Ian

Hi Ian,

My car was doing exactly the same thing (more or less) - until the car has been running a few seconds it seems a bit “soft” and slowly sinks.

I’ve had the brake fluid changed and it’s improved the issue significantly. The pedal still seems to take a few seconds to achieve “full pressure” but it’s improved.

Whether there’s a deeper issue lurking in the shadows I’m not sure, but like you there’s no loss of fluid and so unless it’s flexible lines that are expanding or something not sure what it could be.

For now mine seems ok, there’s certainly no issue once up and rolling.

Jon

master cylinder. get it checked out soonest by a pro - you don't want to find problems when it goes wrong at 70mph.

Thanks both.

Dolphinboy, I've convinced myself its the master cylinder - I assume a seal inside has worn and the fluid is leaking internally.

Any thoughts on a second hand one from ebay / breakers? How common do these fail?

Otherwise, I think I need to bite the bullet and buy part LR012901 - will double check before ordering.

I want to get it changed while car is off the road (until our other car sells - a 2010 RRS TDV6). I will do this job myself along with a few other bits.

Cheers
Ian

As well as the master cylinder I’d also be inclined to check all the brake pads, they tend to cause odd symptoms particularly if the have been overheated for any reason.

my master cylinder was diagnosed by my indie LR expert. he said it is probably letting a little air in. He has over 20 years LR experience so I believe him. get a gen OEM if you can.

Given it’s a fairly inexpensive job I think I’ll replace mine also. The fluid change definitely improved the feel but it’s still “soft” initially on start up. The actual braking is fine but for the sake of £200 I think it’s a good investment.

Jon

Mine needs doing as it keeps loosing vacuum overnight but the hydraulic system is fine so I have been putting it off. Not worth trying to save money on such a critical component so just go with OE. 2012 TDV8 Vogue (L322)

Some of you say you've had a brake fluid change, now when I've asked a couple of Indy's about doing it they suck in air through they teeth and moan about that's a right pita. Is this actually true?

Yes it can be difficult as there is a procedure to purge the ABS via the GAP IID tool and the bleed screws have a habit of seizing in the front calipers requiring removal from the car and new threads cutting for larger bleed screws. 2012 TDV8 Vogue (L322)

I assume the JLR SDD will have the options for purging the ABS? Still need to work out how to use it as its a bit OTT!

If its not raining later, I will remove the Master Cylinder and strip it down to see if there is anything obvious.

Also need to buy another bottle of brake fluid before I forget.

Barmybrummie wrote:

Some of you say you've had a brake fluid change, now when I've asked a couple of Indy's about doing it they suck in air through they teeth and moan about that's a right pita. Is this actually true?

My Indy took a few attempts to bleed mine properly, and they had all the kit…..

I think there is a seal in the MC or something that can get a bit damaged if the brake pedal goes near the floor etc, not cos it can’t go that far, more that there can sometimes be rust or whatever in the bore and it hits that as the cylinder moves more than it usually goes, if you see what I mean….

I had rear brake lines replaced and ended up having to have a new MC too.

You do indeed need to get air out the ABS unit, depending on where the parts get replaced.

No expert, just from memory as to what they said.

 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

You can easily bleed any replaced master cylinder without getting air into the abs block as follows.
Fill the fluid reservoir as normal
Run the pre charge pump until you hear all the air coming out of it.
To run the pre charge pump undo the connector plug and connect 12V and earth to the two connections, they are clearly marked red and black.
Undo the two outlet connections from the master cylinder and press and hold the brake pedal down until the connections are retightened.
Repeat once or twice more as you feel necessary topping up the fluid reservoir as required.
Go to the abs block and disconnect one of the inlet pipes from the master cylinder and press and hold the brake pedal down until the connection is retightened.
Repeat the above.
Repeat for the other inlet pipe from the master cylinder.
Given that no air should have been passed into the abs block you should now have a hard pedal.

the GAP tool makes bleeding a doddle.

Yeah if bleed nipples snap you are in for a world for hurt but given brake fluid needs to be changed every 2 years I'd say it's a problem that will happen one way or another

i actually wonder do the nipples seize because people don't change their fluid, which ends up with a lot of water in it, which in turn corrodes the nipples and probably caliper pistons? Its actually a sport

Not anymore, 4.4 TDV8 now