mlevett
Member Since: 22 Jun 2021
Location: Waterlooville
Posts: 37
  
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| Brake issue - conflicting issues |
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Good afternoon all, I'm hoping someone can help me here as I'm pulling my hair out trying to fix this. So my 2007 D3 has developed a interesting brake issue.
Background:
Mot 2 years ago reported back brake lines were corroded, I've since replaced them from under the pass seat all the way back completely. No issues then other then a soft peddle that the car has always had.
Last summer it developed a scary issue where the brakes failed but seemed to only so this when on a long slowdown i.e. coming off a motorway slip road and slowing down ready to stop at the roundabout. When I got to the end of the slipway I had no more brake peddle travel, it was solid and therefore could not apply any more braking, a release and reapply would then bring the peddle back up and allow me to apply lore brake force.
No loss of fluid or any issues I could find.
Replaced the master cylinder with a second hand one as I assumed it was a internal failure, if I sit with it running I can push the peddle all way and it will slowly creep down. This second hand one was even worse so assumed it was a dud unit and bought a new britpart one..fitted that and was fine, nice solid peddle and stopping was better then ever before.
Now here's the kicker, noticed there is a slight creep again 4 months after fitting the new part. And this weekend I suffered the same issue of no brakes on a slip.road. again no loss of fluid.
Could this be a failure of the new part? Seems odd that 3 units all has the same issue. Secondly today I had a good look and think I spotted a little fluid on the floor dripping off the drivers mud guards. I thought it was from me checking for air in the system but can't see brake fluid squerting that far and there was none on the face just the top.
Looking around the cylinder I could not see any leaks but I did notice a wet patch right at the back of the plastic cowling around the cylinder, but I can't see where it came from or reach to see what it is. Again I don't seem to be loosing any fluid!
So do I have another dud cylinder or does the front drivers pipe come back on itself under the booster and is leaking up in the chassis above the mud guards? Or does the pipe not go anywhere near there on its way to the caliper?
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 18th Jun 2023 6:29 pm |
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Oswiperus
D3 Decade
Member Since: 02 Apr 2010
Location: Chelmsford, Essex
Posts: 1599
 
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I know some Britpart parts sometimes aren't that great but couldn't say about their Master Cylinder.
I assume OEM would be TRW as most of the brake components are TRW on the D3
Here's a link to a TRW Master Cylinder. https://www.famousfour.co.uk/new_parts/ff_part?part=19448
I would satisfy yourself that you have no pipe leaks then try a TRW Master Cylinder. Stu
2016 D4 Landmark current
2022 Defender D300 SE Gone 
D4 2014 XS Commercial - Gone
D4 2016 hse lux montalcino red - Gone
D3 2005 se java black - current
D3 2005 base manual - gone
D2 1999 TD5 E white - current
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| 19th Jun 2023 7:43 am |
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mlevett
Member Since: 22 Jun 2021
Location: Waterlooville
Posts: 37
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Thanks, yes I'm gonna go out and have a look again in a moment. I'm wondering if the hard line from the abs module to the offside front caliper is leaking, does anyone know where it goes i.e. the route behind the engine?
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| 19th Jun 2023 8:24 am |
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L319
Member Since: 14 Dec 2013
Location: Herefordshire
Posts: 2082
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Presumably if there is no loss of fluid there is no leak! Has the oil in the servo recall been done that can lead to no servo action left on long stops.
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| 19th Jun 2023 12:59 pm |
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mlevett
Member Since: 22 Jun 2021
Location: Waterlooville
Posts: 37
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Thanks guys, the recall has been done and no oil in the servo. When I say the peddle goes hard I mean it hits the end of the travel.
As for fluid loss, it does not seem to be losing any, but I did find a small pool of what I think and felt like brake fluid. Hence I am asking if any lines run in that area.
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| 19th Jun 2023 1:15 pm |
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L319
Member Since: 14 Dec 2013
Location: Herefordshire
Posts: 2082
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If you operate the brakes with the engine off, does the pedal go hard after multiple brake applications, ie evacuating the servo, or is it still long travel. If it goes rock hard with little travel it points more to a servo problem
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| 19th Jun 2023 11:03 pm |
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M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8213
 
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Long shot but are you using the correct grade unopened brake fluid?- typical symptoms of brake fluid boiling. It can when others can't,
It will when others won't,
It goes where others don't.
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| 20th Jun 2023 8:04 am |
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Harry365
Member Since: 25 Aug 2018
Location: Lincoln
Posts: 382
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My first thoughts inline with M3DPO.
Have you done a proper fluid change, including the ABS module? Water/air in the line will cause boiling. Gas compresses etc = brake failure, particularly long braking.
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| 20th Jun 2023 10:30 am |
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mlevett
Member Since: 22 Jun 2021
Location: Waterlooville
Posts: 37
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Hi all!
So I see a few replys and I've not had a chance to respond.
1. New fluid, I flushed a good 5l of it though the system when I changed the master cylinder the 2nd time. All bead properly both manually and via the iid tool.
2. Got a 3rd master cylinder under warranty as I'm not losing fluid but peddle goes to the floor (assuming it's got to the end of travel as it's not an instant hard peddle, it depresses and I get light braking as expected, but when it's time to come to a stop it bottoms out, and booster seems to work) on long braking i.e coming off a duel carriage way to a roundabout on a slip road. Brakes are fine till I get to the roundabout and then peddle has run out of travel.
3. Removed the master cylinder today to swap it out and the centre pin in the booster came out with it together with a star type washer. Assume that's not meant to come out and with the issues I've had I've ordered a new booster. I could possibly put that back in but I've never seen one come out in the end of the cylinder before. Can post up photos if required.
So I'm still none the wiser what's causing the issue. But if I'm replacing everything it's gonna be fixed right?? 😂
Did find a little oil in the bottom of the booster but not more then a few mm deep, car does have the modded pipe work so not sure what I can do.
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| 22nd Jun 2023 6:09 pm |
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mlevett
Member Since: 22 Jun 2021
Location: Waterlooville
Posts: 37
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L319 wrote:If you operate the brakes with the engine off, does the pedal go hard after multiple brake applications, ie evacuating the servo, or is it still long travel. If it goes rock hard with little travel it points more to a servo problem
Goes hard when all vaccum is used as i would expect it to as it does on any other car I've driven. Peddle then becomes much harder to push, it does brake but requires a lot more effort. Starting the engine and peddle sinks down till it hits a point then will very slowly sink if I really really push on it.
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| 22nd Jun 2023 6:12 pm |
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mlevett
Member Since: 22 Jun 2021
Location: Waterlooville
Posts: 37
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M3DPO wrote:Long shot but are you using the correct grade unopened brake fluid?- typical symptoms of brake fluid boiling.
Yep brand new container that I got specifically for the job when I changed the master cylinder and as far as I know its the correct spec DOT4.
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| 22nd Jun 2023 6:35 pm |
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mlevett
Member Since: 22 Jun 2021
Location: Waterlooville
Posts: 37
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So...installed a new booster and new cylinder and I seem to have a soft peddle still but....it stops like it hit a wall now so no idea what the issue was.
Soft peddle I mean it's very easy to push down and you feel the brakes work right away. Not sure if that's due to the slightly better booster (RRS SC upgrade from Advanced Factors (Highly recommend them)).
One question! The IID tool bleed process, how's that actually meant to work? Think I followed it but got confused as the timer goes into negative numbers, so do you keep pumping when that's the case? Also how are you supposed to keep the fluid topped up? Mid bleed it runs out while it's telling you to pump the peddle and it's operating the valves.
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| 24th Jun 2023 9:48 am |
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