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This summer I replaced the defective gas gauge on my 1947 Packard with a used unit. The gas tank sender unit worked but it caused the gauge needle to flutter wildly once the gauge came off the full mark whenever the car passed over a bump etc. which I assume is caused by wave action within the gas tank. I have removed and inspected the gas sender and the float arm moves within the full and empty range and activates the dash gauge as it should. The problem seems to be that there seems to be no way to "brake" the effect that sloshing of the gas would naturally have on the float. Has anyone had a similar experience with these units and if so what is the procedure to cure this problem? Is the damper in the gauge or at the sender unit and can this be adjusted or repaired?

It has been a number of years, but you may have a small dead spot. Take the unit out and you will need an old fashioned pointer ohm meter. Put it to ohms. Attach one probe to ground, and the other to the positive or where the wire connects. Move the float by hand and watch the ohm meter needle, watch for any sudden movements. While moving the float up and down, also a bit sideways to check for any open areas. I have in the past just bought an already rebuilt one, can't remember from where. Thanks.

To my knowledge, there is no damper unit. There apparently were 2 types of gauges used in various Clippers according to the Motors manual. Did the replacement sender look exactly the same? Since the needle is fluctuating wildly, your dash unit is a magnetic S-W type. The K-S type is bimetal so needle would respond much slower.

If the senders were the same, tolandis suggestion would be my first also. In addition, with that gauge make sure the wiring connections are good. The schematics show an inline bakelite connector but I'm not sure exactly where it is. That gauge also requires a ground at the instrument cluster so also make sure it has a good solid ground.

The sender is the original and the dash gauge is the magnetic type and is what I replaced. I did do the ohm meter test and it appears to vary as the float rod is moved back and forth. I took it apart to check the windings on the resistor and the contact appear to be OK. The ground wires are fine. I am thinking that the contact on the resistor isn't good enough in places. Is there a diagram or description to show how the contact should be bent. I hate to spend $150 on a rebuilt unit if this one only needs an adjustment. I do have one on my parts car that may be OK. Thanks for your quick response and help! It is very much appreciate BTW this is our Thanksgiving Day in Canada.

Your feeling the contact is not good is probably right. I have never seen any illustration of that particular sender though, and frankly, have not been all that successful in repairing them. I haven't found a way to bend the contact reliably without removing the slide from the arm to get the angle on that tiny piece that makes the connection. As you know, the contact appears to be riveted or peened on. There are people who advertise they can repair, but I don't have any info. If you try and succeed, please share your secret.

I believe the ohm range (78Ω E - 10Ω F) on the later units is about the same as yours, but mounting is different. If your range is within those numbers or the one off your parts car won't work, one possible option is the Ford-Chrysler universal sender for $25 and a couple hours work.

http://www.jcwhitney.com/DATCON-INSTRUMENT-ADJUSTABLE-FUEL-LEVEL-FLOATS/GP_2005714_N_111+10201+600002072_10101.jcw?showCustom=0

I did it on my 56 and it works beautifully. The write up is in the tech tips articles section.

HH56, Once again thanks. I just got back from the garage with an idea. I hooked up the Ohm meter and tested the sender again. One thing I did find was that the ohm reading varied when I moved the rod back and forth within the bushings so I wonder now if the bushing are worn sufficiently that when gas is sloshing the rod back and forth it changes the resistance which translates up to the gauge. I will have to see how the parts car one works when I can get out to remove it. The universal JCW one would be my next choice. Where will I find the tech tip on how you had to modify the one on your Packard? Is that at the JCW site?

Did you place the swing arm parallel to the front back axis of the car? If so, it might work better if the arm was placed perpendicular to the long axis. The original was parallel to the long axis. But, the replacement might work better crosswise. That would make the fluctuation show worse on corners though. Just a thought.

My original worked fine. I took it out to line the tank and now it will ot work at all. I hope it is just the tank ground. Haven't had time to try to fix it yet.

That is a thought although I think the bolt holes only line up one way. I will have to check. I am also replacing the gas line which is original. I found that the old line is brazed onto the fitting that is bolted to the frame to connect to the rubber hose. Is this fitting available with the mounting bracket somewhere and if not can the old line be removed and a new one brazed onto the old fitting?

I could be wrong but I believe all of the 41-47 clippers and the 48-50 cars had a solid line connecting the tank to the fuel line. No rubber hose. Many have been cut over the years and electric pumps and filters added. So, do whatever you need to to make a good connection.

My how to is on the website here.

https://packardinfo.com/xoops/html/modules/article/view.article.php?c8/114

The units I've seen (mostly 51-6) have the ground through the mounting bracket via a thin strip of bronze that connects to the bottom of resistor and the case. A rivet passes through end of resistor, insulator, bronze strip and case. It goes up to where the contact mounts on swing arm & shares that connection. If you don't have that solid ground connection, with worn bushings I can see how that would cause the problem.

As to the fitting, not sure what your car has. Mine appears to be a standard 5/16 inverted flare fitting on the tube end that screws into the tank fitting. The tank fitting is a little different than a 51-6 but again looks like standard 5/16 to 1/8 pipe. Without pulling it all apart, won't swear to that but nothing appears to be brazed and no hose.