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Discussion Starter #1
My 155 000 mile 1.9td needed some new brake pipes for the mot and it passed ok. A couple of months later and every now and then my brake pedal goes all the way to the floor which is extremely scary. I suspect that pumping the pedal to bleed the brakes has killed the seals in my master cylinder, or is it something else?
 

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Scary indeed :eek:. I'd have thought if the seals were knacked it would be constant lack of pressure though. No other ideas tho soz.
 

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One of those moments when you find out that adrenalin is brown.
 

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Just glide into the vehicle in front and use thier brakes to slow down. To reduce damage to your vehicle try retro fitting train buffers to absorb the impact. T:
 

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When you pump the pedal to get the correct level you should find that when you apply the brakes you get a solid pedal. If this is the case then you need to bleed your brakes again. If your pedal slowly sinks to the floor then you have a seal problem. Check your reservior level to see if your losing any fluid. If your fluid is down then check your caliper/wheel drums pistons for signs of a leak.

I used to drive an old mini, the brakes used to fail quite often so i know what you mean when you say your pants fill up:eek:
 

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My 155 000 mile 1.9td needed some new brake pipes for the mot and it passed ok. A couple of months later and every now and then my brake pedal goes all the way to the floor which is extremely scary. I suspect that pumping the pedal to bleed the brakes has killed the seals in my master cylinder, or is it something else?
my advice mate is to get a new brake master cylinder fitted asap

due to the brakes been bled the pedal as been moved a lot more than it normally as in its life service thus the seals have some how been maybe damaged/disturbed who knows the point is its goosed & thats what will be causing your sudden pedal loss

EG: when you press the pedal the fluid is going straight past the seals back into the reservoir hence sudden pedal pressure loss.

hope this helps T:
 

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Discussion Starter #9
Been out and had a play with the van(in the drive not on the road) if I press the brake pedal gently it will go to the floor, if I give it a good prod I get a firm pedal. recon I need a new master cylinder but my local parts place is giving me a choice of two at £100 or £130. Has anyone fitted a seal kit? and what were the results/costs?
 

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Hi Snedboy,

How did you get on with changing the master cylinder - did it solve the problem?

I recently changed a rear wheel cylinder, bled the brakes and after a week I have the same problem as you; If I press the brakes slowly they (sometimes) go to the floor:eek:, if I prod them they're fine.

Sounds like seals to me.
 

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Hi Snedboy,

How did you get on with changing the master cylinder - did it solve the problem?

I recently changed a rear wheel cylinder, bled the brakes and after a week I have the same problem as you; If I press the brakes slowly they (sometimes) go to the floor:eek:, if I prod them they're fine.

Sounds like seals to me.
update:

New mastercylinder from GSF £35 ish (same as golf mkiii, and passat apparently), changed the wheel cylinders too, which were at the end of their life. seemed to solve the pedal issue, but after several re-bleeds the back was locking up too easily.

Went for the MOT and now it failed on the pressure regulator seized.

Come on van, where's the love :*
 

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Discussion Starter #12
update:

New mastercylinder from GSF £35 ish (same as golf mkiii, and passat apparently), changed the wheel cylinders too, which were at the end of their life. seemed to solve the pedal issue, but after several re-bleeds the back was locking up too easily.

Went for the MOT and now it failed on the pressure regulator seized.

Come on van, where's the love :*
£35:eek: My local branch of Eddie Walker quoted me £100-£130 the theiving bas:*rds. Thanks for the heads up I'll get onto that straight away and yes they can be hard to love sometimes.
 

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When you pump the pedal to get the correct level you should find that when you apply the brakes you get a solid pedal. If this is the case then you need to bleed your brakes again. If your pedal slowly sinks to the floor then you have a seal problem. Check your reservior level to see if your losing any fluid. If your fluid is down then check your caliper/wheel drums pistons for signs of a leak.

I used to drive an old mini, the brakes used to fail quite often so i know what you mean when you say your pants fill up:eek:
so did i! theyre an awesome car! so old yet so good! i had a 1982 1275cc, with with minilites, straight through exhaust, no silencer, it ROARED! stage 1 kit! ahhh it was the biz! metallic blue, with white stripes and a white roof with a vinyl target on the top! LOL can show pics if youre intereted? any ways back to t4's / t5's!
 

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Did a new mastercylinder solve the issue?

I have the same. Hard push gives me rockhard brakes that doesnt sink.

Slow soft push - pedal goes to the floor....
 

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Slight servo help with slow pedal and a quick hard push no vacuume in servo
Could be mc but they normally are consistent when failing
 

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Discussion Starter #19
Did a new mastercylinder solve the issue?

I have the same. Hard push gives me rockhard brakes that doesnt sink.

Slow soft push - pedal goes to the floor....
The van's been off the road since I ordered the master cylinder. I'm currently overhauling my calipers so brakes should be nearly new by the time I'm finished
 

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This is an old thread but I'd like to suggest another possible cause of the brake pedal sinking to the floor.
I'm driving a T4 1.9td abl converted to a camper.
A while back I started having a problem with the brake pedal going solid when maneuvering, as though there was no vacuum assist.
After a lot of head scratching and the help of a vacuum gauge I narrowed it down to the vacuum pomp.
Turns out it was half full of oil, guess a seal had gone, so not building up vacuum quickly.

After replacing it (scrap yard parts) the problem was solved.
I then set about trying to figure out why the brake pedal would sometimes slowly sink to the floor if I held pressure on it, this happened while the vehicle was stationary.
Couldn't find any leaks and no loss of fluid, brought me to the conclusion that it must be the master cylinder seals were worn.
Fitted a new master cylinder and lo and behold still had the same problem.
Much head scratching!!
Anyway I discovered that if I held the engine revs (2000 or so) and pressed the brake pedal with my left foot the brake pedal didn't sink anymore.
This brought me to the conclusion that when I pressed the brakes at tick over as the brake pedal is depressed the reason that it sinks is due to the vacuum slowly building up therefore increasing the force through the braking system.
Turn the engine off, press the brake it is solid, start the engine and the pedal sinks, vacuum pressure building up..
Stamp a couple times on the pedal and then hold it sinks, vacuum pressure building up.
My conclusion is there are no problems with the braking system it's a result of the vacuum pomp not working to full capacity.
Will be fitting a replacement vacuum pump shortly
That's my suggestion to this problem!
 
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