total brake failure

[peanut]

well its happened again fortunately at only 20mph in the village.

Went to brake and it might as well have been a marsh mellow under my foot. . Went straight to the floor. I couldn't even seem to build up any pressure.
There is no fluid loss or leaks anywhere and whilst the level was admittedly on the min mark last time it happened it was definitely on the max this time.

The only thing I have noticed lately is a strange sucking gurgling air/flappy noise under the bonnet on the drivers side which I thought might have been the vacuum reservoir ? the large black plastic tube thingamebobby next to the heater intake []

Any ideas anyone ? before I bang her in the garage and ask them to replace everything starting with 'B'[]

 

[tref]

Many years ago I had a car on which if you were to gently brake, the pedal would go to the floor. Stamp on the brake, and you would go through the windscreen. That wasn't much consolation mind. To cut a long story short, that turned out to be the seals in the master cylinder... gently on the brake, and the piston could be pushed down the bore with the seals not expanding out. Stamp on the brakes, and there wasn't enough clearance, and the fluid pressure on the back of the seals would expand them out to the walls of the cylinder. That would match your problem in that there was no fluid loss.

HTH,

Tref.

 

[peanut]

yes I think you are probably bang on the money Tref. I know the front disks need replacing for the MOT so I might as well go ahead and get the garage to replace the master cyclinder as well. Also maybe a service kit for the servo.
I just hope the calipers are ok. I might remove them and service them myself . Wonder how hard it is to replace the front disks on an S2 ?
I used to do all my own spannering once but i've no garage now and the winter is coming on......

 

[Mike_Pollock]

+1 For the master cylinder, but check the vacumn line to the servo also

 

[Hilux]

Almost 100% m/c

Fluid is passing the seals both ways, if you cant see fluid then the rear seal is stopping it leaking out

Vacuum line will soften pedal but it shouldnt go to the floor

 

[rcsalmons]

Its happened again? Blimey is this a regular thing - I dont think I would have driven the car after the first episode.

Rich

 

[peanut]

ORIGINAL: Hilux

Almost 100% m/c

Fluid is passing the seals both ways, if you cant see fluid then the rear seal is stopping it leaking out

Vacuum line will soften pedal but it shouldnt go to the floor

mmm so what do you think is the problem ?

I was very surprised that i couldn't build up a little bit of pressure from furious pumping .?

Because of that I wondered if the brake master cylinder slide was getting stuck at the end of its travel and not returning for the next pedal stroke ?

ORIGINAL: A9XXC

+1 For the master cylinder, but check the vacumn line to the servo also

I am pretty sure that there is something screwy with the vacuum system because it makes this peculia noise when the brakes fail but I can't think how the vacuum system could give pefect braking one minute and complete failure the next!.?

 

[peanut]

ORIGINAL: rcsalmons

Its happened again? Blimey is this a regular thing - I dont think I would have driven the car after the first episode.

Rich

no its not regular Rich. Last time i found the brake fluid level was on Min so I assumed that was the reason. I topped it up and it hasn't happened since in over 1000 miles at speeds up to 90mph !

I definitely won't drive the car again now until the brakes have been completely refurbed. I might have to drive the car a couple of miles to the garage on the handbrake though []

 

[944Turbo]

I think master cylinder too, Brake discs are easy - wheel off - caliper off (2 hex bolts and a hose clip) - the annoying small hex head screw that locates the disc (might need an impact driver) and off it comes (well if it doesnt there are a couple of bolt holes so you can wind it off if I remember correctly

reassembly is the reverse!
Tony

 

[tref]

If anything were to fail on the servo/vacuum side, it will have one of two effects - too much vacuum assitance or too little. Too much and the brakes will put you through the windscreen, too little (i.e., none) the pedal will go hard, but it will stop, and the pedal will not go to the floor... so I don't think it is a vacuum problem. I could, however, understand the servo making some interesting noises at trying to assist you push pedal to the floor, at a point in its travel that it doesn't usually operate.

 

[peanut]

what if fluid was getting past the servo seal and leaking pressure and fluid into the servo ? or the vacuum system . That sudden pressure loss might prevent the MC slide from returning to its normal 'pedal up' position ?

 

[bert gear]

i would say master cyl. easy job to change yourself

 

[peanut]

ORIGINAL: bert gear

i would say master cyl. easy job to change yourself

Hi Bert thanks for your input.
I am quite happy to do the MC myself but front disks and calipers etc is a bit too much without the protection of a garage or lean-to.
Given the age of the car I think I will refurb the servo too at the same time.

 

[944 man]

You can buy a re-seal kit for the master cylinder, I believe.

 

[peanut]

yes I think that is what I'll do if I can find a kit.

Still looking for some discs at a reasonable price.[&o]

 

[tref]

ORIGINAL: peanut

what if fluid was getting past the servo seal and leaking pressure and fluid into the servo ? or the vacuum system . That sudden pressure loss might prevent the MC slide from returning to its normal 'pedal up' position ?

Then you'd see fluid loss?

Of course, this is me being tight... I know it is the braking system and the normal advice is "replace everything, brakes are important!", but... I see no point in disturbing stuff which is sound, and besides - I always consider steering more important... if your brakes fail, you might just be able to steer round whatever the problem is... if your steering fails mid bend, well can you stop before you hit something?

 

[zcacogp]

ORIGINAL: peanut
Still looking for some discs at a reasonable price.[&o]

They are chuffing expensive. Always. And the xcheapest ones you'll find are made by Zimmerman, which seem to be badly-regarded on here.

I bought mine from Bert a few years ago; can't remember why. I doubt he was the cheapest but it was the best option at the time.

You could try looking on German eBay - there is a seller there ("911 Teile") who was doing genuine 944 parts very cheap. I bought a waterpump from her (yes, her) without a problem.


Oli.

 

[Eldavo]

Discs are very straightforward to change, as 944Turbo says or look on Clark's.

 

[peanut]

thanks Oli and Eldavo . Trouble is I've only got a slot-in parking bay like you have at Tescos so i'm not sure I can do this myself if I'm going to stay on good terms with most of my neighbours []

I usually source the materials for my local indie to do the work but they moved recently. I'll have to find another local garage I can trust.

 

[vitesse]

Round here you frequently see people using those green & white striped barbecue shelters for roadside repairs-outside Autoglass in Liverpool there is often a Chips Away guy using one on the carpark-be reasonable with your neighbours & blag a bit of extra room-even though I have a decent garage,I much prefer to work outside-the light's so much better.