Vaccuum powered antenna on 1948 Cadillac Fleetwood

[Richardonly]

Hi All,
Finally hooked up my vaccuum lines after a 9 week wait for the wiper motor rebuild.  The antenna works from the left radio knob to raise and lower it.  There is a hissing from the knob (an air leak) and was wondering if it is a line OR part of the knob.  This knob also controls the volume.
I would hate to remove all the things in the way, only to find out it is the volume knob, which may be almost impossible to find .
The antenna lowers, but cannot rise as there is not enough suction.
Any ideas???
Richard

[Jay Friedman]

Are you sure the hissing is from the knob and not from one of the hoses connected to the radio?  Stick your head under the dash with a light and you may be able to hear it better as well as see any possible hose leak. 

If the hissing is, indeed, from the knob it may mean that the vacuum switch which is behind the volume control inside the radio may have to be dealt with.  This can only be done by removing the radio and working on it on a bench.

[49 Convertible]

As you already know there are 3 vacuum lines running to the volume knob on the left side of the radio.  the vacuum from engine goes to the center post and then there are 2 other posts 1 line goes to the to the forward post going to the top of the antenna tube and the other line goes to the  back post  and on to the bottom of the antenna.  I suspect one of the lines has rotted out and you are losing vacuum there.  The switch usually does not fail...check your rubber tubing from antenna to this switch

herman

[Richardonly]

Gentlemen,

Thank you both for your responces and the information.

The leak, I strongly believe is from the volume knob, as if I gently push it in , maybe 1/32 or 1/64 of an inch, the noise stops.  The 1948 is impossible to see behind the dash and where the radio is.  The glove box will probably have to be removed, then the speaker housing (a metal box) and then the radio. 

I fear disturbing other things in my efforts to reach the control knob, only to find out it may not be replaceable.  1948 was the only year with this type of dashboard and clearance is maybe 9 inches ( an estimate ).

Perhaps a strong cleaner would allow the antenna to rise, although it lowers 80% of the way at the moment, yet the vacuum noise would still be there, which could be annoying.

Any further thoughts?  Thank you again.

Richard

[P W Allen CLC# 20193]

Richard,

This sounds very much like the problem I had with my 53 after it came back from being painted (interior and exterior). The antenna always worked fine, but when I got it back, it would not go up all the way, but would go down fine. Here's what I found. During the painting process, the radio was removed and reinstalled after painting. I checked all the vacuum hoses that are hooked up to the volume control and all were in the right place and secure. With the motor running, I continued to fiddle with the volume knob, pulling and pushing it, trying to get the antenna to go all the way up. No luck. I did notice though, that the knob didn't seem to have as much travel in and out as it did before the paint job. That's when I discovered the problem. There are two knobs on each post. An inner and an outer. the inner knob is dished out so the outer knob fits into it. I pulled all the knobs off of both sides and examined them. I noticed that the inner knob from the station tuner side(right), was dished out much deeper than the inner knob from the volume control side. Hence the problem. When putting everything back together, the shop had the inner knobs reversed. This restricted the travel of the volume control, so it could not be pushed in far enough to get full vacuum on the antenna mast. Once I put the deeper dished inner knob on the volume control side, the antenna worked perfectly as before. Sorry to be so long winded. Now, this may or may not be the problem with your 48, but it's worth a look. Good luck! By the way, I think you already know this now, but these vacuum antennas bottom out at around 10" from the fender.

[Raymond919]

I'd appreciate if someone could just correct me about my understanding of the power antenna. I have a '49 model and think that the antenna is probably the same as yours. I have not yet tried my antenna since it's not yet hooked up to the vacuum. I'm slowly getting the car in order and concentrating on the engine, tranny, and it's general appearance so far.
My understanding has been that the antenna should be totally retracted into the fender and when the button is pushed, it would rise only the length of its first segment. After that, it would be raised by hand. Going down, it would only go down the length of the lowest segment and have to be pushed the rest of the way by hand resulting in its being totally inside the fender. From reading this, it seems like a portion of the antenna would always stick up above the fender. I'd appreciate any information someone can send who has a properly working antenna. Thanks

[P W Allen CLC# 20193]

Well, all I can tell you is that mine works properly and it does not go down to the fender. It bottoms out at about 10". I bought a custom fit car cover from California Car Covers. They include a seperate grommet for where the antenna sticks through. I'm sure others will respond with the same story.

[R Sotardi #11719]

My 1950 works the same as Mr Allens. The antenna is always about 10 inches exposed. When I push the knob, which is on the right on the Wonderbar, there is a light hiss and of course a small drop in vacuum, but the antenna shoots right up and goes down even faster. Check vacuum lines, then pull the antenna and make sure you are not losing vacuum in the piston antenna rod seal( a plastic disk and rubber seal inside the tube that  the antenna is attached to ), or on the lower plug. If you losing suction from the top, the antenna will be litargic going up but come down quickly. There are 4 small holes in the plastic , and air can escape through them and pass through the seal. I closed the holes and solved the UP issue. I really wish that these parts would be reproduced. They most assuredly are the cause for much grief. Ron

[Richardonly]

Hello Again,
I have not looked at my original posting in a week or so, but would like to thank you all for the additional information.  It is usefull and gives me a few more things to check into.
Thanks again, Richard