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[Fiona]

Hi all

Have noticed that my brake pedal has become very soft.

The brake fluid level is correct so don't appear to have a leak that i can see. Car is stopping but not as fast as you would want it to be in an emergency.

I got my handbrake cables replaced a while back. Could that work have disrupted something?

I read on Google about brakes needing bleeding, can air just appear in the system from time to time?

Lastly there was a nice little plum of blue smoke from the exhaust on start up from cold but it didn't happen when the engine was hot, is this what diesel cars do when cold or do i have a in the nasty oil leak somewhere maybe or should have turned the key twice in the ignition unto make sure the glow plugs had a chance to work properly?

[albitz]

Bleed the old fluid out of the system,and replace it with new fluid.

[Fiona]

Bleed the old fluid out of the system,and replace it with new fluid.

I dread to think when it was done the last time, so am I right in assuming that brake fluid looses it's effectiveness over time?

[Entwood]

Bleed the old fluid out of the system,and replace it with new fluid.

I dread to think when it was done the last time, so am I right in assuming that brake fluid looses it's effectiveness over time?

Yes, it is also "hygroscopic" - absorbs moisture, so the "water content" within the fluid builds up over time, when hot (heavy braking) this water content turns to water vapour - a gas - gas is a compressible fluid, so when you apply the brakes you compress the gas instead of moving the brake pad .. same as having air bubbles in the system ....

So, change the fluid but ALWAYS use newly purchased fluid....  a can of 15 year old brake fluid that has been sat in a shed with a corroded lid is probably in worse condition than the fluid in the brakes already !!

[Fiona]

Ah thanks now I understand 

[Shackeng]

Bleed the old fluid out of the system,and replace it with new fluid.

I dread to think when it was done the last time, so am I right in assuming that brake fluid looses it's effectiveness over time?

About every 2 years is good.

[symes]

I use silicone brake fluid--does not mark painted surfaces nor absorb moisture 

[Kevin Wood]

I would check the disks and pads for wear while you're at it too. Often a spongy pedal can be attributed to a sticking piston or caliper slider, which will result in uneven pad wear. It may even be that the pads are worn or glazed and the need to apply more pressure gives the illusion of a spongy pedal due to the extra travel required.

[Andy B]

..... It may even be that the pads are worn or glazed and the need to apply more pressure gives the illusion of a spongy pedal due to the extra travel required.

which was the case for my spongy brake pedal