Hello, Went to start up, started no probs, went to apply brakes, right to floor!
All brake fluid leaked out over the winter.
It's presently at the shop to have the air removed from lines, etc.

Do I need a new master cylinder? (it's never been touched) If so where?

 

Yes you do, for safety and I have had exactly the same experience with my 1966 Mk 2 while going downhill...the fact that I can write about this is almost a miracle. In my case a new aftermarket seal kit had been put in the master cylinder and it failed. We put in a brand new master cylinder and booster unit from XKs Unlimited and all has been well. The brakes are up to modern standards with good pedal feel and stopping distance ( but it remains a single rather than dual line system).

 

Fine, the brakes are now being sorted out, but where did that fluid go ? It has had all winter to do its second trick, namely to strip off all the paint wherever it lands.

 

I'm betting the fluid filled the vacuum chamber cylinder inside the booster.
I'm surprised it didn't all get sucked up in the vacuum line into the intake manifold. (lots of white smoke when this happens)
It's probably filled the vacuum tank in the fender well.

Time to overhaul the braking system...
New master cylinder and booster for sure.
Best check the calipers as well, the bores are probably rusted and pitted.
Don't forget your flexible lines too _ just replace them.

 

Look under your floor mat. Sometimes drips into compartment, but agree with JeffR1.

 

The car is back, brakes work perfect, they found no leaks on the system, so yes were did the fluid go?
If it went into the booster, wouldnt that cause some tell-tale symptoms?

 

The booster holds quite a bit of fluid, but when it does reach a breaking point, the brakes will continue to work normally, but the excess brake fluid will get sucked into the intake manifold and be burned.
If the seals are marginal inside the booster allowing the fluid to escape into the main vacuum cylinder, then I suppose the brakes could fail.
Not trying to scare you, but it should be looked into.


And if they found no leaks, that is where the fluid went _ inside the booster.

 

Agree, it's time for a booster rebuild. However we mustn't forget the Reservac tank that sits between the booster and the manifold. If any fluid has been sucked out of the booster, some will have ended up there, I think. Apart from the non-return valve these have no moving parts so it's just a matter of draining it off.




The slave cylinder in these boosters, (UK=Servo), is cast iron, and I can remember rebuilding mine in the 80s, and carefully cleaning the working passage where the piston with its seals operates. With the age of these things, a light hone to remove marks might be beneficial as it's obvious the surface where the seals sit may be corroded thus the seal doesn't seal and fluid leaks past into the vacuum chamber. If the unit is to be rebuilt, a depth gauge is needed to set the piston rod length.

 

Hello, This is a simple one? What oil filter fits, I have a Bosch 72121, but can't quite remember if this is correct, too many autos.
Or a Hastings LF115, the Wix no. 51515.
The Bosch looks right?