Scunnered with the brakes

I replaced the servo on my motor before the rebuild and the brakes were brilliant, much much better than they'd ever been. During the rebuild I replaced all of the brake lines and for a bit the brakes were still great but over the last few weeks I've no started getting intermittent problems with them. With the engine off it feels like I can build up decent pressure in the pedal but as soon as the engines started, especially first thing in the morning, I feel I need to pump the brakes a fair bit first to get any decent braking effect. The pedal goes down quite far and I can tell the brakes aren't as efficient as they had been. At times though the pedal feel and braking is excellent but more often than not it's soft and not as good. It's not losing any fluid, there's not a bawhair of air in the system and the vacuum is good. Any ideas? The master cylinder is probably original but id have thought if the seals were gone I'd notice fluid loss.

300tdi 110

Brake vacuum pump is my thoughts.

kevstar said:

Brake vacuum pump is my thoughts.

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Any way I can test it? With the vacuum hose off the servo I'm still getting a good vacuum (as far as I can tell)

With the pipe off servo and engine on tick over put thumb over end of pipe, If the pipe holds itself on vac is good. Check the valve the pipe fits to on servo is working.
With the master as it is old you may have issues with seals inside allowing some internal fluid bypass giving the soft symptoms.

tottot said:

With the pipe off servo and engine on tick over put thumb over end of pipe, If the pipe holds itself on vac is good. Check the valve the pipe fits to on servo is working.
With the master as it is old you may have issues with seals inside allowing some internal fluid bypass giving the soft symptoms.

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Wouldnt issues with the seals inside the master show as fluid loss though? Or not because it's still staying within it. I'll check the vacuum again today

Yes that is the issue, the fluid stays inside so nothing to see. Have a look in the reservoir with a good light, black stuff at the bottom will be tiny bits of the seals.