My boss has an 03 plate Mondeo diesel and he said he had an issue on a couple of occasions where he went to brake and the pedal was soft and spongy but as soon as the pedal was released and reapplied the pedal was ok

My first thoughts were that it was a master cylinder starting to let go.

Car was dropped at a local garage who have diagnosed the issue as being down to the CV joint allowing movement causing everything to get hoy and making the fluid overheat.

I might be a pessemist but this sounds like bull to me. I know on track when I've ended up with a spongy pedal it's taken quite a while for the pedal to return to normal again.

Thoughts and opinions please?

 

It's also very possible that it's the hub flange. Check to see if the hub nut comes loose. If so the hub flange is worn, and it needs replacing.

It happened on mine, and the pedal would go randomly soft, and sometimes completely the floor. Was a bit disconcerting!

This bit gets worn, and gives exactly the symptoms you describe..

 

Certainly bullshit about his thought process of fluid overheating..

But a warped disc, worn wheel bearing, etc etc, anything that can cause the disc to be untrue and this will push the pads back whilst driving. So first time you hit the pedal, you're just making up that distance. Second or third application will see the pads at the disc and back to normal

 

pad knock off happens when the bearing go slack as well

 

I would say a worn wheel bearing too.This used to happen to toyota land cruisers.

 

I had a similar problem with my Focus RS..... I fitted a new driveshaft and a few weeks later had a bearing noise when cornering hard.... Jacked the car up and had all the signs of a shagged wheel bearing (play in bearing). I bought a new bearing from Ford (that hurt), fitted it and it was exactly the same, fitted a genuine Ford outer CV joint and all was good (basically the after market CV joint wasn't 100% right and wasn't butting up against the back of the bearing giving a similar feel to a worn bearing).


Steve

 

Car could also be on very old past its best brake fluid, which can boil if a brake is binding slightly.

Fluid boils, turns to steam no brakes till it cools