kaiserbud

I am trying to repair my leaking Main Vacuum Reservoir. :smash:

The system (at manifold) is expecting 18-20 in/Hg according to the book.

What should I expect the reservoir to hold up to (in/Hg) and for how long?

All I have been able to check is 10-12 in/HG (hand pump)and it eventually leaks down to 5 after 5 minutes and after 10-15 more minutes it goes to minimal.

Is that good enough? The reservoir is to accumulate enough vacuum in case the motor is not generating enough or for closing the headlamps and wiper door after motor is turned off.

One last technical thing please --- Actually the repair could work for a vacuum test but not a pressure test, so I was hesitatant to re-perform the initial test I did (Filling the bathtub up with water and blowing into the tank while it was submersed). I did not want to subject the repairs to something they would never encounter and possibly damage my repair.

thanks


[Modified by kaiserbud, 9:04 PM 11/30/2002]

Dave68

Check out this great pressure convertion calculator at
http://www.aip.org/avsguide/refguide/pressure.html

If you type in a pressure (vacuum) of, let's say 15 in Hg, the equivalent pressure in psi is roughly half that amount. Given the geometry of the vacuum reservoir, I would venture to say that a calibrated internal pressure test should not destroy your repair job unless you are simply smearing RTV over the leaking seams. If you are cleaning, abrading, and applying something like JB Weld, it should hold up to an internal positive pressure of 10 psi or so.

As far as the vacuum leakdown test, I would think that the leakage rate you have specified is indicative of a leaking reservoir. If you plug one end and pull a vacuum on the other, the leakdown rate should be much slower (basically, zero leakage). However, if all tubes are attached, minor leaks in any of the connections could result in a fairly significant leakdown.

The best way to check for vacuum leakage is with a helium detector. The bad news is that those testers cost a small fortune. For low vacuum (what we have here), a hand pump with shutoff valve should suffice.

kaiserbud

Dave - great info - thanks for the conversion chart too.

I (hopefully) repaired it by soldering the slight cracks that had appeared in the tank. I cleaned the tank witha wire brush and initially used Flux - but I did not like it. Once complete with all soldering, I ground it and smoothed it out. Just minimally though - just enough to knock off any big glumps. :smash:

I went ahead and did an internal psi test (If you call it that....I blew repeatedly into the tank as if I were blowing up a balloon - but that was maybe 2 breahths). No air bubbles came out at all when I submesrsedit in water.

My next step planned was to take it somewhere Monday and get it sandblasted - then treat for surface rust and repaint. Anyone advise on correct color?

Any comments are appreciated.


[Modified by kaiserbud, 10:19 AM 12/1/2002]

kaiserbud

In regards to the correct color, here are the paints I have slated to use. I was hoping to get Chuck G to advise on whether the DE-1634 Flat is the one to use on the Vacuum Reservoir. Thanks Chuck.

I used the DE 1634 for a Flat look and sprayed it on the firewal and faded the spray half way down the firewall as suggested by the NCRS guys in a previous post.

I used the DE 1635 for a semi-gloss and sprayed it on the hood latches so far. But I am wondering if they should have been a natural color with just a clear on them.




[Modified by kaiserbud, 1:31 PM 12/1/2002]