vacuum guage

[BillyBob]

The vacuum guage on my '63 has intermittent operation at best. Lines and connections checked and found to be secure. Is there an OE-type replacement? Is rebuild a possibility?

[Guest dapy]

I recently asked Jon Myer about mine that registers +10 in normal R2 operation. He said there is a very small hole in the instrument that with old age gets plugged so the dampening that it is supposed to provide doesn't. He suggested removal and sending to him to fix. Apparently a common problem.

[Stan Gundry]

I have been told that what I did in the same situation does not work in theory; but I am here to tell you that for some reason it worked in practice. Try it because you have nothing to lose. Here is a description of what to do copied and pasted from my book:

A columnist in Turning Wheels once suggested that the way to fix this was to inject a little lacquer thinner into the gauge through the nipple where the rubber vacuum line attaches. The theory was that the thinner would serve as a solvent to dissolve any deposits that might be in there and free of the mechanism to operate freely.

The theory sounded good to me, but I had one concern: If there were any internal rubber parts would the lacquer thinner destroy them? Now, I have never taken a vacuum gauge apart and there may be no internal rubber parts, so my concern might be misplaced.

Nevertheless, I wondered, and I did not want to gamble by taking unnecessary risks with my sluggish but irreplaceable gauge.

So I decided to try something less harsh that might still do the jobTri-Flow Teflon lubricant. It worked perfectly. Here is the procedure I followed. I injected Tri-Flow into the nipple and let it soak overnight. The next morning I shook out the Tri-Flow and filled it again. I went through this sequence several times with the obvious purpose of getting the gunk out.

Then, to free up the mechanism, I directed compressed air at about 50 psi at a right angle over the top of the gauge’s nipple. (Notice I did not say into the nipple, but rather the airflow should be at a right angle to and over the end of the nipple.) By what is called the venturi principle, that created a vacuum in the gauge and caused the internal mechanisms to work back and forth (you learned about the venturi principle in high school physics). I would direct the air across the end of the nipple, and remove it. I did this a number of times. The purpose of this was to further clean and free up the mechanism and to lubricate it.

The result was, and still is, a vacuum gauge that is immediately responsive to the fluctuations of intake manifold vacuum.

[Guest dapy]

As I read your solution I assume that the vac.pressure instrument has to be removed from the panel and reinstalled. How difficult is that? Any risk of damaging the instrument? Can a non- mechanical person do it?

[Stan Gundry]

Yes, the vacuum guage has to be removed from the dash. How hard is it? It has been a number of years since I did it, so I do not remember how hard it was. But you do not have to be a mechanical genius to do it, but it helps to be a bit of a contortionist! Will it harm the guage if you follow my directions? All I can say is that it did not harm my guage. I was careful to not blow compressed air into the nipple that goes into the body of the guage. After the Tri-Flo lubricant had been carefully dripped into the nipplle and allowed to soak for a few days, I blew compressed air across the end of the nipple. That process loosened up whatever was stuck in the guage and had the effect of pulling the Tri-Flo lubricant out, much like an old fashoned atomizer or a cheap Badger spray brush.