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vacuum tank 2600

1627 Views 7 Replies 4 Participants Last post by  dretceterini
Hi everybody,

What should I do with the vacuum tank ? I don't know if it is working properly, don't know how to test it and if anything has to be changed, what would it be and where to find it ....
I have restored everything on the braking circuit except that one and when I unplugged the vacuum tank, it helps a lot the engine to run smoothly !
So far, it is filled with brake fluid, not sure if it is normal but maybe it is ?
Thanks for helping...
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Hmm. I wonder if you're really talking about the vacuum tank or the brake booster.

The vacuum tank is the container that has two hoses connected to it. One hose comes from the intake manifold, where the vacuum is generated by the pistons during the intake stroke. The second hose goes to the brake booster, where the vacuum is used as a brake assist, creating a larger force on the brake cylinders than comes from the foot pedal. It is important to understand that the vacuum is supposed to be a static pressure that, once the vacuum is built up after starting the car, should change only minimally when the brakes are engaged and released. There should be no brake fluid in the vacuum tank. If there is, it can only have come from a failed brake booster.

With respect to testing, I would say that should be easy: Insert a T with a pressure meter and see how long it holds the vacuum. If you want to test the tank by itself, take it out of the car, pressurize it with compressed air and submerge it in water. If you see bubbles (due to a crack), there is something wrong with the tank. However, I think this would be a very rare thing to happen.

If the car is not running smoothly with the hose attached, there is probably brake fluid sucked into cylinders 5 and 6 when starting the car. You may see black fluid being spewed out of the tailpipe.
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Hi Ruedi,
Yes that is really the vacuum tank I am talking about.
After reading your comment, I guess that it get filled with brake fluid before I restored the brake booster.
So now, I assume the easiest way is to empty it and try again...
At the same time I am restoring the complete carb assy and water it might take a while !
By the way I take the opportunity to ask where I could find a coil , it is still working but I prefer to be on the safe side and have a spare one....
In your case, chances are that the repaired brake booster now has some brake fluid from the vacuum tank in it -- which will make the seal of the vacuum chamber fail again. I would take it out of the car once more and see if any fluid comes out of the vacuum hose nipple. If there is fluid, you may have to open it and clean it once more.

I can't help much with respect to the coil, as I'm switching away from Bosch and Marelli to an Accel coil that complements my conversion to electronic ignition (but I'm keeping the old one in case a future owner wants to return the car to its original state).
Electronic Ignition

Sorry for the thread highjack.

Ruedi could you comment a little more about your conversion to Electronic Ignition. I still haven't found a suitable conversion

Sorry for the thread highjack.

Ruedi could you comment a little more about your conversion to Electronic Ignition. I still haven't found a suitable conversion

A friend machined a toothed wheel for me that (together with an external box) replaces the contacts as shown in this thread (I did it for a Marelli and a Bosch distributor I have). Today, I'd rather buy a 1-2-3 dizzy as discussed here and in other threads.
Thanks Ruedi
I would suggest you check the rubber bladder in the tank to make sure it is not leaking. Brake fluid can get sucked back into the intake manifold, and eventually destroy the rubber carb mounts and rubber bits in the carbs themselves!
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