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Dodgy brakes???

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Hi, wonder if anyone can help / suggest what's wrong. Used car todayto go to work. Fine this morning, coming home noticed brakes felt strange. A bit spongy, and if I keep pressure on ,the pedal moves down , probably to floor if I let it. Any ideas. Happy Xmas to all.  Alan

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56 minutes ago, alank said:

Hi, wonder if anyone can help / suggest what's wrong. Used car todayto go to work. Fine this morning, coming home noticed brakes felt strange. A bit spongy, and if I keep pressure on ,the pedal moves down , probably to floor if I let it. Any ideas. Happy Xmas to all.  Alan

Master cylinder begining to fail maybe. 

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Have you checked the fluid level? There would be a loss if a leak were present. Think it's obvious that you should not be driving the car! 

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Spongy brakes means they need bleeding. To check, 'pump' the brake pedal to see if comes back up and becomes 'hard'. You are losing brake fluid somewhere. I wouldn't venture out until you've found where you are losing the fluid. As a last resort, top up and drive VERY SLOWLY to your garage/mechanic

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Just had this on the Mini Cooper, turns out to be the ABS pump, £700 fix.

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Thanks all. One thing I've seen mentioned is if it's not Master Cylinder it could be ABS Pump causing similar problem. Anyone experienced ABS pump problems/replaced. Thanks

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Having messed about with cars and bikes for the best part of 40 years i always work to something my late father taught me (flight engineer on Shackletons then Bristol Britannias folowed by Boeing 720B as well as a stream of cars he owned) "Start with simple stuff. How does the system/component work and ahet would adverse symptoms be if it has a failure/wear "

ABS units in these are fairly simple so an unlikely, not impossible though, cause.

Be systematic. Your symptoms are of a failure as it happened after working fine previously. The fact the pedal sinks suggests that you have either a servo vacuum leak or fluid leak/by-passing master cylinder piston seals.

Look at the master cylinder and check the level to see if there is any loss of fluid.

Check the servo vacuum pipe isn't split or leaking/insecure.

Get a second person or film using your phone as the pedal is depressed to see if anything happens in the resevoir to indicate fluid not moving

If fluid has been lost find where it is going from by checking all lines, connections, bleed nipples and hoses. The rear lines are prone to corrosion but can be DIY replacement (search on this forum)

 

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Thanks for that, when rain stops will investigate further. 

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Now rain stopped, had a look, got a low fluid warning now, and resivour empty. No sign of fluid around calipers/wheels, so either a pipe gone or knackered master I am assuming. Excellent start to new year, ha ha.

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Look at the nearside near the sill under the passenger door. There's a metal block there that is a brake pipe junction.

It's not the block itself that corrodes but a length of pipe towards the rear. It corrodes where it attaches to a clip. A simple repair if that's where the leak is. 

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Still thinking ABS pump.

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what was the outcome - as my brakes do not feel right.

It stops and passed an MOT but the pedal will travel a long way,
I have searched the google and it appears across the pond at least 987 and Caymans are prone to a soft pedal.
People seem to upgrade to a 997 MC [touted very often as a GT3! ] and this firms up the pedal feel.

I have replaced 
Pads, discs and flexi lines all round. And flushed through new brakefluid.


{The did not or have nots}
{yet got my wife to push pedal and person bleed - I used a pressure bleeder and did so until no bubbles present}
{activated the ABS pump when I did the bleeding - google research suggests its such a small amount of fluid in there}
{bled the clutch point}

Having driven many cars it certainly feels like the volvo I once had where the MC was failing - 62K miles seems quite low for that to happen?

any thoughts?
 

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Hi, my problem was my rear hard brake lines had corroded  and I lost my fluid, possibly over a period of time, as I'm not the most diligent at checking my levels.Your problem sounds like the Master Cylinder if you're not loosing fluid, though it could be leaking. My son's caterham problem was like yours, was a dodgy master cylinder. 

The garage said it was a fiddly job as the pipes go over the top of engine, so not much fun doing DIY on the driveway.

It was £485 to do it, so hope it is the MC as they are only about £90, plus fitting, or DIY.   Cheers. Alan

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4 hours ago, alank said:

Hi, my problem was my rear hard brake lines had corroded  and I lost my fluid, possibly over a period of time, as I'm not the most diligent at checking my levels.Your problem sounds like the Master Cylinder if you're not loosing fluid, though it could be leaking. My son's caterham problem was like yours, was a dodgy master cylinder. 

The garage said it was a fiddly job as the pipes go over the top of engine, so not much fun doing DIY on the driveway.

It was £485 to do it, so hope it is the MC as they are only about £90, plus fitting, or DIY.   Cheers. Alan

Thanks Alan

Think I will try a 2 person bleed and just check again all the lines - must admit not checked the reservoir since I did it so that might be a good place to start.The GT3 MC is a bit more around £200

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Never had an MOT warning on my car for brake lines, so I'm a bit concerned @17 years that it will happen soon. Sounds pretty expensive. I think I read on here some where about copper custom pipes can be reasonable?

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It's not the cost of the pipes, it's the labour. Mine was 6hrs,. Slam

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They rot  because they are hidden by the under covers, hence the mot won't pick it up . Alan

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6 minutes ago, alank said:

They rot  because they are hidden by the under covers, hence the mot won't pick it up . Alan

It is the ones under the car that are exposed, the rust is seen at the two clip points.  If you catch it early enough you can remove the surface corrosion that has also made the grease at the clip point look rusty, hence the Tester wants to fail it..  Degrease and clean up the pipe with a little emery cloth and re-grease, if not pitted, and clip it back in.  If pitted, new pipes.....

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Wish I had room to get under her. Looking to upgrade my home soon, garage and drive is certainly a must have (or at least potential to have that). 

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1 hour ago, alank said:

It's not the cost of the pipes, it's the labour. Mine was 6hrs,. Slam

Yes I've heard it's a bit of a ball ache to get the pipes where they should be. Was 6 hours the full system?

 

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I'd be wary of the 'clean the surface rust off the bits you can see' approach. I did this for many years on my VW T5 camper until one day I was about to set off on a 300 mile trip and lost the brakes as leaving the drive (split systems will still give some braking but after a few pumps all the fluid will exit via the hole).  One of the more hidden pipes had corroded through and burst on first press of the pedal that day.  While some of the OEM steel pipes not exposed to road spray were still ok - a good look at the rest found plenty more that weren't.  As I replaced them, they pretty much fell apart with a little bending. I live in North Scotland so see more salt on roads then most but even so, OEM steel lines WILL rust if exposed to good old UK weather unless cleaned and dried like some sort of concours exhibit. 

On a related point, while checking my boxster over, I found the small brake line that goes under the front wheel caliper (connects the 2 caliper halves) was rubbing on the disk! At some point, I'm guessing during a tyre change, it had been bent towards the disk. If you look at the pipe, there is a rubber collar in this location to protect it slightly. My brake disk had worn through this and was just starting to eat into the brake line. Worth a check any time the front wheels are off....

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On 2/8/2020 at 8:13 PM, Dubdubz said:

Thanks Alan

Think I will try a 2 person bleed and just check again all the lines - must admit not checked the reservoir since I did it so that might be a good place to start.The GT3 MC is a bit more around £200

All fixed..old school manual bleeding with an assistant. Pedal now good, and the amount of air was small but obviously enough to make the pedal feel soft.

I do now see where the wooden pedal comments come from though...

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