Citroen ZX Brakes Conundrum

nesssalmon · Post by **nesssalmon** » 11 May 2006, 15:13

Hi

I have been having all kinds of idling problems

with my 1.4i monopoint 1994 zx. (Which I have mentioned on the forums)

But I think the following is related: when I put my foot down on the brakes I can hear a creaking noise. this also makes the car run badly idling stalling etc?

So firstly do I need new pads? They seem quite low. Do I have a low brake indicator? are the Calipers leaking causing the engine to run badly? The brakes are all part of the vacuum system therefore I guess a leak would create the idling problem?

Any ideas would be greatly appreciated?

I have replaced the stepper motor. Coil, Points, ECU temp sensor, checked for vacuum leaks elsewhere.

Many Thanks
Robert

bxbodger · Post by **bxbodger** » 11 May 2006, 15:56

The only way to tell if you need new pads or not is to take the wheels off and look- if there's only 2 or 3mm of meat left on the pads then you need new ones.

There's no connection between the brake fluid and the engine, but the brake servo, which provides assistance to the brakes is connected by vacuum pipe to the manifold- you may need to check that all is as it should be here-no air leaks into the manifold,etc.

AndersDK · Post by **AndersDK** » 11 May 2006, 15:59

Hi Robert -

The creaking is from something moving on the brakes. Most likely a rear brakes shoe as these normally moves a lot during braking. Front brakes rarely makes any noise at all since its only a piston moving 1mm out the bore.
Its your foot on the brake pedal that initiates the creaking.

If your front brake pads seems "quite low" its a very good idea indeed to replace them - while you have your attention here. The pads should have new pad wear cables in the package. These will connect to a connector bush residing on the hub. May however have been cutted off long ago by a garage. Meaning you need a new pad wear cable from hub to inside the engine bay too.

There is a vacuum activated servo to give you power assisted brakes as long as the engine is running. This is the large tin canister you can see in the engine bay - just opposite to where the brake pedal is located.
This vacuum canister contains a large rubber diaphram - of which one side is connected to the engine intake by a rubber hose. The vacuum from the engine intake thus "charges" the vacuum canister against a strong spring which in turn then holds assisting pressure ready for you braking the car.
When you press the brake pedal - the other sid of the vacuum diaphram is opened to free air - and thus the servo assist you.

If the engine clearly is protesting when you use the brake pedal - you then have a leak in the vacuum canister servo piping - or the non-return valve is failing. This valve is located exacvtly where the engine hose enters the canister.

If you get stuck in finding the problem - dont fear paying a good repute garage help you. Any recent small to medium size car have exactly the same system - so any garage would know how to service a brake vacuum servo. Would defo not cost you a fortune.

nesssalmon · Post by **nesssalmon** » 11 May 2006, 16:19

Thanks guys for your excellent help.

Front brakes rarely makes any noise at all since its only a piston moving 1mm out the bore

This is def coming from the front, and the pedal seems to go quite a way down, this is when the creaking, straining sound is heard? I had the wheels of the other day and got the wife to push the brake pedal and its seems as though it is the cylinders creaking?

Also when the car is say started in the morning, she runs perfectly, then I can push my foot repeatedly on the brake pedal (hard) and cause the car to run v badly and even stall.

Thanks again
Robert

Sl4yer · Post by **Sl4yer** » 11 May 2006, 18:25

My ZX 1.4i did a similar thing, although not to the point where it stalled. The engine did shudder a bit though.

I think I suspected the non-return valve, although I never changed it before I got rid of the car.

James

AndersDK · Post by **AndersDK** » 12 May 2006, 15:09

nesssalmon wrote:Thanks guys for your excellent help.

Front brakes rarely makes any noise at all since its only a piston moving 1mm out the bore
This is def coming from the front, and the pedal seems to go quite a way down, this is when the creaking, straining sound is heard? I had the wheels of the other day and got the wife to push the brake pedal and its seems as though it is the cylinders creaking?

Also when the car is say started in the morning, she runs perfectly, then I can push my foot repeatedly on the brake pedal (hard) and cause the car to run v badly and even stall.

Note : the valve (should, a must !) comes with a new rubber grommet.
Thanks again
Robert

Right then -

Seems the front brake calipers needs a bit of an overhaul.
The whole caliper body slides on bushes that can get dry. Its not a complicated job - but a major job it is though.

You may need a new non-return valve - the one I mentioned above at the hose port on the canister body. This is specific to the brakes vendor - i.e. Bosch, ATE, Teves etc. - according to your exact ZX model/year spec.
If this valve leaks then the engine can get false air and may easily stall when the brake pedal is applied. But first check is the condition of the rubber hose - especially where fitted over the studs.

Note : the valve should come with a new rubber grommet.