Technical Newbie with no brakes

[Loppie]

Hi all, a newbie with a problem. Ducato 2001 2.8 JTD, MOT fail, rear brake load compensator. Decided to fit a new one, and as brake pedal was sinking a bit, replaced the master cylinder. Now, the pedal is rack hard with no servo, but apply pressure, switch on the engine and the pedal sinks down to the floor. Gentle pressure makes it sink faster than hard pressure. Tried several new master cylinders, and bled system many times. No leaks, all brakes adjusted, not losing any fluid. Fluid is going somewhere when the pedal is pressed - but where. Help!!!

 

[ecunotemu]

Seized caliper /unevenly worn pad can give the feeling of a squishy pedal, old flexible hoses can bulge also.

First step buy a brake clamp and clamp off the flexible hoses one at a time and try the pedal again. If there is an issue with bulging/stuck caliper you'll feel it right away.

There is a massive brake servo and an engine driven vacuum pump so the its normal for the pedal to feel soft when the engine is on as long as it doesn't bottom out.

 

[Loppie]

Thanks for the info. Will give your suggestions a whirl. Its the pedal bottoming out thats got me.