Posted by Clint Dixon [74.206.62.210] on Sunday, March 01, 2015 at 09:40:32 :
In a post below, Nick attached an image of a Stewart Warner 701-1569 fuel sender.
I assume/assumed this aftermarket sender was retrofitted and used on an early WDX-WM300 Power-Wagon, and I was totally on-board with that idea, until the mentioning of: "used the lock ring to twist lock it to the tank like the original."
The early sending units did not twist lock to attach to the tank.
To back up a little - the first sending units listed in the parts manuals for the 1946 WDX through early 1951 B3PW (through serial number 83922966) (part number 1188 955) were not the typical electromagnetic units that most shade tree mechanics are familiar with today. Those early ones were somewhat unique in that they operated on the principle of electrical heating of thermostatic bimetal blades by resistance wires wrapped around them - which, in turn, caused them to bend and move the gauge needle. These systems required one "hot" wire to feed the dash gauge with power and two wires that connected the dash gauge to the tank sending unit. The tank unit must also have a good "ground" which was assured by the factory through the mounting technique it employed, but which now may be necessary to add a ground wire between the sending unit housing and the truck frame on old vehicles that display a lot of rust, dirt, and corrosion.
Tom Petroff answers about every question that comes up on the subject, sometimes more than once, and usually with carefully scanned pages from service manuals and with in-depth explanations. Sometimes I wonder just who all is listening to him...
To add to the confusion, there were three different part numbers listed for the gauges used on B3PW-WM300 model trucks from serial number 83922967 (early in 1951) through 1968. These were of the electromagnetic type and they required only one wire to connect the dash gauge to the sending unit. Some of these sending units used a lock ring to twist lock mount to the tank.
Nick, can you elaborate a little on the Stewart Warner 701-1569 fuel sender that you found? Were there any specification sheets that came with the unit? Google, Dogpile, and ebay searches turn up no information on that particular sending unit. What was the original application listed for that particular unit? Does it indeed connect to the dash gauge with two wires? Where can they be purchased?
Thanks.
Junior
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