What did you do today?

[bub2006]

It's all gone to shit on the van front. Me and friend made a crack on getting the brakes held,bled and bled as well as for good measure rebled again. Spare servo looked worse than the current one and the master cylinder had moisture on the rod which says the seal isn't in rude health so decided to sort out the current situation of brake parts.
Heavy gauge metal wire usually used for garden fencing was used to loop over the reservoir and pull it more tighter down onto the master cylinder as there was a bit of rocking showing maybe a weak seal and rebled the brakes front to back.
Pedal still felt like it was sinking a bit lower than it used to but after driving the focus all week I just put it down to different pedal feel as the focus brakes are rather keen. Took it a quick spin up the road and things felt fine. Bonus as I can't really afford to lose a night at the takeaway.
Off I went to work and I noticed at speed it needed some pushing to slow down. Something definitely not right.
First delivery done and on way back to the shop the brakes seem to be getting worse. In traffic after a few pushes on the pedal it seems to lose servo boost and the brake pedal doesn't really do much to halt progression but also t the same time they seem to be binding on a slight bit. After a few seconds they realise and the pedal goes back to sinking until a few more pushes of pedal when again it loses boost.
Ended up having to abort mission as I really didn't fancy rear ending someone when the usual dicks on the 50mph road doing 35-40 slam on at last minute to pull into pub car park.
So what the fuck is happening? Hard pedal after a few presses say servo failing or vacuum pump and the slight bind then release could be servo or air in the system. The sinking pedal says the servo and vac pump are working but I'm losing pressure or air in the system.
There's no visible leaks,vac lines are intact and good condition. Calipers are free,hand brake cables aren't sticking,vac pump clicking and has suction. The new rear cylinders are fitted correctly and don't seem to be leaking.
I don't want to get rid of the van for 2 reasons. I couldn't replace it like for like due to financial reasons but mainly I just like the van. It's always been a good workhorse. Yes it may need a spot of welding in the next year but I've done over 12500 miles in 6 months mainly around town which is probably equivalent to 25k motorway miles and it's never gave me major grief.

[Hooli]

Master cylinder seals? You did say it looked damp.

[bub2006]

The original one on the van was dry. The moisture under the pedals doesn't feel or smell like brake fluid. I always have my heaters on warm to my feet too because diabetes.

[Hooli]

Ahh I lost track in your description then.

[bub2006]

There is also a hiss when brake pedal pushed. It's always done that though but I can't recall if I've had it on something else or not.

[Hooli]

Air in the ABS block? Some need cycling via diagnostics to get the air from there.

[bub2006]

Ahh I lost track in your description then.

We did first thing there was brake fluid going to pedal but it seems more like moisture/condensation. We have had the master cylinder off and the seal is dry as well as the rod so it can't be brake fluid like I first thought.

[bub2006]

Air in the ABS block? Some need cycling via diagnostics to get the air from there.

No abs on this one.

[Hooli]

Air in the ABS block? Some need cycling via diagnostics to get the air from there.

No abs on this one.

Ahh I thought it was new enough to be a must have.

[Drum]

Check the flexi hoses maybe

Failing that, I would change the master cylinder. Doesn't have to be visibly leaking for the seals to be fucked.