I have read all the threads on every Land Rover site I could find, still no solution found.
It all started back when I had leaking master cylinder mounting grommets....
Replaced master cylinder (properly bled);
So far I have bled the brakes 5 times (both single man with pump and the 2 man version).
Yesterday had the brakes pressure bled at a brake shop.
Took out the ABS fuses and disconnected the ABS harness.
the problem has been the same......brakes work "somewhat" (soft pedal as it has always been). They work that way for a few miles, after about half hour or so, pedal goes nearly to the floor, if I pump 3-4 times I get a little braking power but it still sinks to the floor. I usually use the gears to slow down incrementally until I have to actually come to a full stop that is when I pump them up to stop.
The shop I went to is "Brake Masters", I took it back after a few miles (after they did the power bleed and said brakes work fine), because again I had no pedal. they told me at this point they will not be able to help me with the Land Rover.

 

What brand of master cylinder is the replacement you installed?

For whatever reason non-original equipment master cylinders have a reputation of not working well on these trucks.

Is the vacuum hose properly connected to the servo?

 

Bought it on Ebay from a Land Rover after market parts retailer: LK8Parts | eBay Stores
Yes, I cut the split ends of the vacuum hose connections and installed new hose clamps.

 

this may or may not help you....
a ways back I replaced a Honda clutch master cylinder with a cheap after market one (dorman I believe .... garbage!) - when it got hot out or alot of driving - clutch MC would not work fully and would have to be pumped. I replaced it with a factory and 6 yrs later it works perfect still.

At this point I would make some dead end brake pipes and connect them to the MC - let the truck run on a hot day in the sun for 30 mins - see if you get the same results - then youll at least isolate it to the upper end.

personally - Im betting on a bad MC - it sounds like what my Honda did

 

I suspect that may be the problem and it usually happens when it gets hot/ hotter.
Any recommendations as to buy from Atlantic British or Rover North, I notice a significant price difference between those 2 ..

 

I looked at both RN and BA's MC choices. ...... I recommend rockauto's beck/arnley model. The BA's MC for $249.00 (would be my choice if I had to choose between RN and BA) looks like it may be the Beck/arnley but I cant say.

I have had very good experiences with Beck/arnley parts. They are not the cheapest but they have always worked and fitted properly.

Also if you have a local NAPA - they tend to have good after market parts. just another option.

Believe me I know how frustrating it is to do work and it not work properly - which is why my recommendation is so direct - Im done with doing $h!+ twice.

I admittedly got lucky with my ebay reman MC but I knew it was a gamble - its lasted 4yrs and is feeling like she will need replacing soon. I will replace it with Beck. (I was in the last 4yrs I came to the conclusion Beck/arnley is the cheapest aftermarket parts that actually work).

 

Thanks much for your advice, I will follow up with the Beck brand.

 

Or you could PM Paul Grant for an original gently used MC. I'm sure he has them. It would be less expensive, excellent condition and original equipment. I've personally bought many parts from Paul that always exceeded expectation. He only pics and sells the best of the best.

 

+1. Paul is ultra reliable.