Clutch Master Cylinder for HJ60

[87 HJ60]

Does anyone know anything about the clutch master cylinder that's on the HJ60, and I think BJ60?
The clutch master cylinder uses vacuum to assist the clutch pedal similar to the brake master cylinder. Apparently the FJ60's don't use this setup.
I had posted a couple of threads relating to this but I still haven't had anyone reply that knew of this system. I first had a thread about a mystery noise from behind the dash and another regarding the mystery noise having been discovered to be caused by a vacuum leak of the clutch master cylinder.
A couple of days ago the leak went from intermittant to all the time. I would hear a high pitch whistling noise as a result of the leak. But if I just put a slight amount of pressure on the clutch (but not depressing it) the noise would go away. As I depress the clutch the noise would appear again but again go away when the clutch is depressed all the way.
Now the funny thing is this afternoon the noise stopped. No more whistling noise and it appears no more vacuum leak, at least for now.
Just want to add when the vacuum was leaking the clutch still operates fine. The only difference is that it takes a bit more effort to step on the clutch.
My question is: what's going on with the clutch master cylinder and any ideas what I should be checking and looking at in figuring out this problem?
HELP....

 

[rodcarolino]

usually the leak may come from the shaft seal between the master cylinder and the booster, its also common for the push shaft to rust...

 

[Granite Grinder]

Sounds like the clutch vacuum tank is hooped. On my BJ60 the brake master cylinder started leaking one day. I kept topping it up, but couldn't tell where it was leaking, then it finally failed. When I removed the master I could see the leak was at the pushrod end. Doh! I probably have over a litre of brake fluid sitting in the vacuum can, which will eventually eat the metal and diaphragm, in fact, even after replacing the master, the brakes still seem a little harder to push. Luckily this truck is being parted out.
GG

 

[Tapage]

Honestly .. the first time that I get a vaccum leak in Tencha, I proceed to disconect the vac from the clutch booter .. and after that I bought a mini truck master cilinder ( no factory clutch booster ) and make the swap ..

Very impresive nuy the Tencha clutch it's more soft thatn before and even compared with the FZJ80 clutch.

my .00002 cents ..