19 hours ago, grajack said:

It's a 1.8 Tdci 2006

Just been out to double check what comes up on my 1.8.

Forscan (my version is 2.3.0) does not show an ABS Service Bleed function for it.

However, there is an ABS self-test option. I am fairly sure this operates the ABS valves, so may well help in getting air out of the ABS if combined with normal brake bleeding.

I would've thought you should be able to bleed in the conventional way. The ABS service bleed is only really required to expel air (or old fluid) from the normally-isolated parts of the ABS pump. Given that a servo change would've been performed with these parts isolated (that's their default state) air should not have gone in to them. Any air in the upstream components should be able to be pushed through the ABS pump without issue. 

50 minutes ago, MJNewton said:

The ABS service bleed is only really required to expel air (or old fluid) from the normally-isolated parts of the ABS pump.

Yes, I agree with that.

I had re-read your very useful post on ABS bleeding:

But Graham said he "cant seem to get rid of the air from the system "

So I thought maybe the ABS had got used with some air in the system, and it got into the hard to get at bits.

The other possibilities I can think of are:

That the downward sloping parts of the hydraulic lines from master cylinder might need a reasonable flow to expel all air downwards.

Also I know that if a lot of air gets into rear calipers with internal handbrake mechanism (like when changing a piston seal), it can be a pig to get it all out. But that is unlikely to happen if the rear calipers are undisturbed.

 

Agreed, and perhaps I should've prefixed my comments with the caveat of 'In theory...'! ;-)

Thanks for the comments guys.  I've since forced the ABS to activate by braking suddenly a few times and it does seem better, after the system has settled over night, the brakes are great, however after a few pumps they get spongy again. I'll try to bleed them conventionally again with a pressure tool and see what that brings.  Again thanks.