What is the internal difference between a 6 volt and 12 volt temperature sender?
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Which one matches your electrical system? If 6 volt then use the 6 volt unit, vice versa for 12 volt. Don’t mess around trying to figure which is which unless clearly marked on the housing. This is much too critical a part to either “guess” which is correct, or what goes where! Order a new one from. SI or other trusted supplier. After all it’s only your engine you are talking about!
Others may have correct resistance readings, etc. I would simply err to the safe side as opposed to trying to figure which is which. Am I missing something? A little more info would help give better advice.
Hugh -
Thank you for your reply. But my question remains what is the internal difference between the two?Comment
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The Larger Size Sender with probably 5/8" Pipe Thread were used 1947 to Mid 1957, so Late '57 to '64 would be about 3/8" Pipe Thread and being beyond the 12 volt changeover in 1956, there were NO 6 Volt Temp. Senders that small size.
I am speaking of Stude. V8 Engines that I am more experienced with, but I believe the 6 Cyl. followed along pretty closely the same.
Of course the OHM's Resistance Value of 6 Volt Units is different than 12 Volt.
I did read here somewhere, that Stewart Warner (SW) did use the same resistance value on the Fuel Sender as the Temp. Sender but I can't verify that.
The OHM Rating on SW 12 Volt Fuel Senders is 240 to 33.5 Ohm.Last edited by StudeRich; 04-13-2023, 04:38 PM.StudeRich
Second Generation Stude Driver,
Proud '54 Starliner Owner
SDC Member Since 1967Comment
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The motor in my '51 Champion is a 185 replacement motor designed for replacing motors from '47 to '54, part # 536332. When installed a conversion package was also required. I purchased a NOS cylinder head designated for a '58 Champion. This remains a 6 volt car. The pipe thread on this head is 1/4 inch. The original head pipe thread is 3/8. Of course there are no senders available of that size through the Studebaker network. It appears the only solution is to increase the size of the opening to accommodate a 3/8 sensor.Comment
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The secret is to find a 1/4" threaded base sending unit with the same resistance range as the stock Studebaker unit. And back then most of these gauges were supplied by subcontractors like Stewart Werner for MANY different auto makers. So you may be able to find, for example, a Chevy or Dodge sender at 1/4 inch and the same resistance range - or a universal sender. It DOES NOT necessarily have to be a "Studebaker" part (oh the BLASPHEMY! LOL). So, if you can find someplace or someone (Radio Roy knows I'll bet) who can tell you the specific resistance range of your stock sender, you can search for one with a 1/4"base.Originally posted by Edsel Face View Post
Worst case, instead of drilling and tapping your head (which is what I interpret your statement to say you are contemplating) you could also buy a matched set with the 1/4 inch base sending unit and transplant the internal workings of that gauge into the housing/face for your Studebaker gauge. It's not that tough to do.
On my '51 Ford truck I converted both the Temp Guage and the Oil pressure electric gauges to Mechanical (for the 12 volt conversion) that way. And no one would ever know the difference.Attached FilesLast edited by Big Dan; 04-14-2023, 07:33 AM.Comment
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"It appears the only solution is to increase the size of the opening to accommodate a 3/8 sensor. "
Instead of drilling/enlarging the hole in the head, you could also look at plumbing fittings. Sometimes a street Ell or a reducer will work, although it might not look as nice.
Thinking of something as the "only solution" stops you from thinking/exploring other options and limits your creativity.Last edited by RadioRoy; 04-14-2023, 09:56 AM.Comment
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Classic Instruments and Stewart Warner sell senders to match any gauge resistance and thread size. Senders are not voltage sensitive.Comment
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Was reading this thread last night, and spent quite a lot of time on Stewart Warner and other sites. Could not find any definitive information on resistance range for S-W temperature senders, new or old. Now we know that S-W fuel level senders come in six volt and twelve volt versions, with different resistance ranges, and that fact makes it a PITA for people doing conversions and engine swaps, etc.
I see two possible situations. One, the senders for six volt gauges do, in fact, have a different resistance range than those for twelve volts, and S-W simply does not support the six volt stuff any more at all. The fact that pipe thread size change coincident with the voltage change supports this.
Two, the resistance range for the senders never changed, and S-W simply altered the design of the gauge head itself, by changing the resistance of the compensating element, so that the gauge would work on twelve volts.
This would be easy to test. Simply take a known good sender from a six volt Stude, and a known good sender from a twelve volt Stude, Connect each to an ohmmeter with clip leads. Read the resistance value at room temperature, 120F, 160F, 180F and 212F (boiling water). If they track pretty closely, then you can use whichever sender fits the hole in the head. If they diverge, and the divergence increases with temperature, then yes, you will have to find a six volt sender for your your six volt panel gauge.
I don't have a pair of known good senders at my disposal right now, or I would do this myself and report back.Gord Richmond, within Weasel range of the Alberta BadlandsComment
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Re-threading the sender hole in the head should be no big deal. If it will allow you to use the correct or current sender that is readily available , that's the route I'd likely take.
Originally posted by Big Dan View Post
Cool Dan! I've done the exact same thing on many cars. But I usually go away from mechanical gauges to electric ones. This is one of my VW's. I replaced the internals of two Magura mechanical fuel gauges with VDO electric oil pressure and oil temp gauges, then installed a later speedo which has an electric fuel gauge in it.
This is my '54 Chevy wagon, where I put '75 Ford F100 gauges in it's housings.
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here is a resistance list for most gauges. Most of the aftermarket has standardized as using the Stewart Warner resistance. Every Studebaker I have owned had Stewart Warner gauges from the factory.
IF GAUGE IS: OHMS EMPTY OHMS FULL USE CLASSIC SENDER: GMC 1964 or earlier 0 30 Sender SN36 GMC 1966 to 1997 0 90 Sender SN38 GMC 1998 and later 40 250 Not Available at this time Ford - 1987-later
(Unleaded Fuel only)16 158 Not Available at this time Ford (pre-1987); AMC 73 10 Sender SN39 Toyota-Nissan 1985 and later 90 0 Sender SN38 - mount movement Upside-Down Stewart-Warner 240 33 Sender SN33 or SN35 Auto-Meter 240 33 Sender SN33 or SN35 Comment
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Since you are listing Other Makes, I think you can probably add to the SW Resistance List 1956 & On 12 Volt: Hudson, Nash, Packard, Willys, International and most Boats.StudeRich
Second Generation Stude Driver,
Proud '54 Starliner Owner
SDC Member Since 1967Comment
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Yep, and somehow the conversation shifted to Gas tank sending units, different voltages, etc.Originally posted by RadioRoy View Post
This inquiry is for a TEMPERATURE GAUGE SENDING UNIT in a '51 Champion with a retrofitted Champion 185 and a 6-volt electrical system. Needs a 1/4 inch threaded base and resistance matching the stock '51 Champion Gauge!Comment
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