Another clutch master cylinder/booster question...

[87 HJ60]

Here's a question for all you guys that have a BJ/HJ60 that have a vacuum assisted clutch master cylinder.
I've had an on going problem where the diaphram seems to have a leak in the vacuum booster assembly that creates a loud and very, very, very annoying hiss. My question is can a remove that vacuum line supplying the vacuum to the clutch booster unit, plug it and continue to use the clutch without doing damage to anything?
I know without the vacuum assist that the clutch will require more pedal effort but it sure beats being deafened by the annoying hiss.
This would only be a temporary solution until I can find another clutch master cylinder/booster assembly. And speaking of which, does anyone have one for sale...??

[Camarillo Smith]

I recently converted my FJ60 to an HJ61 and had to convert the Aussie right hand drive components to my left hand vehicle. I was having problems with the clutch vacuum booster leaking down and the clutch getting progressively harder/stiffer to push in. Looked at my firewall when a buddy pushed in the clutch and watched the firewall flex. Yours will most likely do the same and if done long enough I believe it will weaken your firewall through metal fatigue.

[87 HJ60]

Did you end up fixing the leak?

[rchalmers3]

87 HJ60,

If you live in a metropolitan area, there are shops that specialize in brake booster rebuilding. While a clutch booster is something kinda rare, a rebuilder of brake boosters may still have enough generic materials to get your clutch booster repaired.

Does the leak occur only while operating the pedal or does it constantly leak?

Rick

[Camarillo Smith]

Yes found one the two check valves on the vaccum tank was sticking and not holding vaccum. In addition there was a metal "Y" connection in the vaccum lines that had a restriction that didn't let it recover very fast after you worked the clutch several times. Replaced it with a brass "T" and now have 27" of vaccum and the system works properly now. Clutch is stiff upon first depressing it to start since there is no vaccum but once it fires up it quickly build vaccum and the clutch pedal pressure is light. Have you checked all your vaccum lines for holes or leaks? Are yousure it is in your master cylinder? I was sure it my MC but then found the real problem. Good luck.

[87 HJ60]

The leak occurs all the time but there are certain areas where it leaks more than others. That is, depending on if the pedal is not depressed or how far the pedal is depressed the leak varies. For example if I don touch the pedal it leaks like crazy, along with a real annoying and loud hissing noise. But when I begin to depress the pedal the noise goes away, or is very quiet, but still seams to leak.
After I shut the engine off (foot off the clutch) I can hear the vacuum hissing out from the system. Within a couple of seconds the vacuum is all gone.
As for repairing the master cylinder, everyone I've mentioned this to (vacuum assisted master cylinder) has never heard of such a system.
I was planning on hopefully buying a working used unit and replacing mine with it. I haven't really considered taking mine apart and figuring out what's wrong with it and fixing it myself since I've never taken one apart. I wouldn't be afraid to try and fix it myself except I don't have a repair manual and I have no idea what's on the inside....

[Camarillo Smith]

If the leak is determined to be with the clutch booster it can be rebuilt. The 12HT uses a specific brake booster unlike the other diesels and mine in the 1/2 cut was bad. Marve Spector had it rebuilt at a local shop and it works perfectly now. Inside there is a diaphram that may be your problem. They use a heavy spring inside so it takes some special equipment to disassemble and reassemble these parts but they can be rebuilt.

[Tapage]

Disconect it, it donsen't afect anything else ( more than your left leg ) and block the vaccline from the vacc tank

But .. been pased this issue, I recomend adapt a non vacc clutch master .. as I do in my Tencha, I used a minu truck clutch master cilinder .. and it's by far more soft than the factory vacc one ..

[rchalmers3]

What you are describing sounds like the leak may be only the operational shaft seal, where the rod from the clutch pedal goes into the booster. As the rod slides through the seal, areas of contact change the amount of sealing, thus making the noise vary.

That seal(s) will probably be available at a brake booster rebuilding shop, like the above poster mentioned Marv used. I anticipate the parts are the same as used for Japanese cars brake boosters. You will want the rod to be inspected and cleaned/polished as well.

Your truck won't be down for more than a day if you locate a rebuilder shop first and plan your approach to have it repaired. Your idea to replace it is sound, but more expensive and complicated, due to availability of another unit.

Will you please post photos of your system? I have not seen one of these units.

Rick

[87 HJ60]

Will you please post photos of your system? I have not seen one of these units.

Rick[/quote]


Here's some pics of what's in my Land Cruiser.
The first picture shows the vacuum system and connection to the brake and clutch master cylinders.
The second picture shows the clutch master cylinder/booster unit.
The third picture shows the vacuum reservoir. The two hoses at the end of the canister supplies the brake and clutch master cylinders. The two hoses connecting at the top of the canister is the supply from the vacuum pump on the rear of the alternator.