Y 60 PATROL brake bleeding query

[field patrol]

hi new to forum

1996 swb 2.8 td patrol- great machine but the brakes have been causing me problems- hope some one can help!

have tried following haynes manual instructions for bleeding brakes i.e. start with load sensing/ by pass valve first, then rear left, rear right, front left, then front right...

have tried this periodically but spongy feel in brakes keeps coming back

have tried blanking off the two outlets from master cylinder to see if it is faulty but we think it is okay

 connected system up again and left load sensing valve to gravity bleed for 3 hrs

topped up reservoir and tried to bleed again

good pedal to start with then just air in system (again!)

wonder if it is anything to do with load sense valve?

any suggestions greatly appreciated

also anyone got a brake system diagramn?

cheers, field patrol

[auto]

Sounds like its the master cylinder seeping through. It would give you good pedal then slowly the fluid would seep past. With engine running pump pedal ( do not bleed!!) allow the vacuum in the servo to rise. Then turn engine off, there shoulod be resistance in the pedal after few pumps, if there is no difference at all then its the servo, otherwise its the master....or maybe both!! (i had both go on mine!) There is no rebuild kit available for the servo anymore, (you can make one though!) They are about £60 new, the master is £150 ... i think!