brake assistance please!

[ermie571]

Hi all!

need some help with my brakes.

Syncro 1.9 dg

new passenger side front calliper approx 3-4 months ago.
No further brake issues since

driving last week the hsndbrake / low fluid level flickered going round a roundabout. Brought home, parked up and checked. Fluid indeed low. did the checks on the floor around the pedals - all dry. Slave in engine bay looks dry as well. So bought dot 4 and topped to max.
Without engine....clutch resistance fine and normal, brakes - lower resistance than normal. but some.
Started engine....clutch remains normal, brake pedal has nothing, even with repeated pumping. Turn engine off, 2 pumps and and the reduced resistance returns.

Soft pedal normally means air? right?
looked at vaccuum pipe in engine bay....its not in its prime, but it looks in one piece (I know this means nowt and can still be leaking)

please can some kind soul be as kind as to tell me where to start looking?? (and an explanation of resistance when no engine, and no resistance with engine would also be great!)

Thanks in advance!

(Oh, I have noted where the level is now...and will advise if it falls. The bloody stuff must be going somewhere...but if I cannot find the leak its recovery to the garage I fear!)

Em
xx

[lloydy]

Hi Em, i'm by no means a expert on brakes, but if your losing fluid and can't see it.. It could be the rear wheel cylinders or a internal leak on the master cylinder.
Dont forget about the clutch circuit as this fed from same reservoir..

[ermie571]

Thanks Lloydy. hadn't forgotten clutch circuit...but that appears to be ok at the moment

Can't work out why, with a full reservoir of fluid I have nothing on the pedal when the engine is running....

[waltraud]

I would always visually inspect all joints to calipers and rear cyclinders closely with a good torch ditto brake pipe joints. But tbh if there is a leak you should lose new fluid at some point. I thjnk Lloydys idea abou th master cylinder internal leak seems most probable I.e. fluid getting past an internal seal? Check for visible leaks closely I think. Perhaps a joint thats suddenly got loose and let air in. ........and wait for expert advice;)

[ermie571]

Thanks!

will have another look and feel around...lol

x

[bigherb]

Had it actually run out of fluid to get air in the system?
Or if no other leaks then it is often the rear seal in the master cylinder has gone and the fluid is disappearing into the servo.

[kevtherev]

Had it actually run out of fluid to get air in the system?
Or if no other leaks then it is often the rear seal in the master cylinder has gone and the fluid is disappearing into the servo.

My thoughts too.

[armyphil]

Rear brake cylinders. That's the easiest thing to check. Wheel off drum off look for any wetness.

[California Dreamin]

Em....like the others have said......but as a quick explaination: with 'SERVO' assistance, what ever pressure you apply to the pedal is being multiplied several times over. Any air is therefore being compressed to practically nothing but in the process the pedal is flooring.
Air is amazingly compressible, think of it this way, the tank a 'Sub Aqua' diver uses would hold about 4 - 5 breaths of air by volume if it were not compressed. As it is that tank probably holds as much air in it as the average room!

Likely cause:
. Rear wheel cylinder leaking (most likely)
. Brake master cylinder leaking directly into the brake servo (you may also notice exhaust smoke as the brake fluid gets sucked into the inlet manifold, petrol engine)
. Brake master cylinder tandem seal failure (can happen after brake fluid change and full pedal travel)
. Clutch master cylinder leaking (you should have fluid on the carpet although it is possible to miss)
. Flexi hose ballooning/split/leaking.
. Metal brake pipe corrosion/leaking.
. Brake calliper seal leaking (fairly rare)

Martin

[ermie571]

Rear cylinder looking a possibility culprit. Thanks all x

[Titus A Duxass]

Rear cylinder looking a possibility culprit. Thanks all x

At least that's a low cost area.

[waltraud]

Hope you get an easy fix.

[ermie571]

ok - so have a puddle of fluid sitting in the bottom of the wheel. Other wheel perfectly dry. Think I have found the culprit!

Many thanks all for the pointers.


so - to change

1. Jack van and remove tyre
2. Lower vehicle onto axle stand
3. remove drum (with assistance of hammer if necessary?)
4. change cylinder....back to haynes for this one!
refit.

any tips? Not done this before! Any "watch out for this..." "Don't do that" "It could do this"??

Have a litre of dot4 ready and waiting.
Good jack and axle stands at the ready too.

thanks folks

EM
xx

will let you all know how it goes

[Titus A Duxass]

Relatively straightforward job this, just make sure you give the slave cylinder screws a good squirt of release fluid/penetrating fluid and have a blow torch handy.
I find a blast of warmaleme often helps loosen things off.

[New Kentish Campers]

Pleased you've found the problem.

Me, I'd buy another can of fluid and bleed the entire system to remove the old fluid while I'm about it. Always good to have nice clean fluid in the braking system particularly