The Stovebolt Site Forums The Shop Area The Electrical Bay Resistance values temp sending '56 1/2 ton

My '56 1/2 ton Chevrolet has a not so original engine: 1970ish 350CID. At least it's 1 step up from my previous ('55) ride: it drives :drive:

The instrument cluster is original and I'd like to keep it that way. However for reading the temp of the engine, I would need a matched temp sending unit.

I've read up in the forums here and elsewhere on the internet and I can't really reach a conclusion on the resistance values for the complete range of let's say 100-230F the original temp sender would have. Snippets of info tell me that e.g. at 212F the resistance would be somewhat like 92-111 Ohms (still a large range btw).

I would need those R values to go to the next step, which is to find a temp sending unit with the same/similar as possible resistance values.

Anybody any tips on primarily the resistance values from the original? Alternatively, a sender unit which has proven to work the range of the indicator exactly?

Thanks for the help!
Peter.

Hy PAF, welcome, as far as I know the resistance range for the temperature sender is the same as the fuel gauge 0-30 ohms The Niehoff p/n for the sender is DR134A, hope that helps.

also, if someone there can match the numbers, NAPA TS6469 or Standard TS6T work

Bill

3B, Bill,

0-30 Ohms seems far off from what I've read so far. The DR134A and the NAPA TS6469 are advertised for 1958-19xx Chevy truck (not 56). Since the '56 was a 1 year only send unit, it might work relatively OK, but I can't compare the Ohms. Thanks for the tips anyway.

Still looking for that 1 person who knows the Ohms.... :-)

Peter.

no idea what the ohmage is, but can't imagine why there would be a difference for 56, same gauge, same engine ... the 55 2nd was a mechanical gauge, in 56 the electric gauge started, and didn't change, I've had a couple dozen 55-59 gauge sets here and they're 100% interchangeable and the numbers I gave have worked in various different years I've had, 6 or V8

your gauge does not read degrees, it reads "cold" - "hot", and that's how any sender works, as the engine temp goes up, the resistance changes, doesn't matter the exact value, if you want to know what the gauge is telling you in degrees, you need to use a good digital thermometer on the engine/rad and compare, always a good idea because original gauges are not precision instruments

also with that 350, make sure you don't run the recommended 14# cap on the original rad, 350's will develop that much pressure, your rad and particularly rad core, won't be happy

edit: realized why 56 might be different, the threaded hole in the head of the 235 was still the smaller size hole for the mechanical sender - meaningless for your modern engine

Bill

Hy PAF, a bit more research has yielded another part Echlin p/n TS6179 resistance is listed at 91-111 ohms at 220 degrees F, it is actually listed as for a 56 Chev truck, the newest application listed is a 69 Chev car or Corvette. I was sure in my head that I had read that you could use the fuel gauge tester to test the temp gauge as well... faulty memory I guess, hope the new number helps.

Bill: interesting remark on the 14# cap. Is that a 14 psi cap? I recently changed it to 1 bar (14.5 psi) because the one which came with the truck I felt was too weak: kept spewing/blowing steam. I have to admit I made sure the cooling was working properly afterwards, but the new cap opens nicely when the engine is warm and spews into the spill tank.

regards,
Peter

3B: thanks, I'll check it out!

Here is some car info from google

http://www.trifive.com/forums/showthread.php?p=1268557

Don't know how the info relates to truck engines
SS55 posted some numbers

DADS50: thanks, will check it, I hadn't found that one yet.