Coolant temp gauge

[ray_mcavoy]

The correct sending unit for use with the original temperature gauge was GM #1513321. Lectric Limited makes an accurate reproduction.

As Captainfab said, the original temperature sending unit wire was dark green. However, instead of being in the loom with the alternator wiring, it was in the engine harness with the starter & coil wiring. That harness has a 6-cavity plug where it goes through the firewall up above the engine over toward the passenger side.

The temp sender wire originally ran along side the coil wiring in that loom and then branched off on it's own near the coil. From there it ran through a section of asphalt coated fabric loom clipped to the side of the valve cover. On inline-6 engines the sending unit was originally located in the lower thermostat housing and on V8 engines it was originally in the intake manifold just off to the driver side of the thermostat housing.

1968 & newer small block Chevys had the temp sender located in the cylinder head between the #1 & #3 spark plugs so you might have to extend / re-route the wire a bit. Although some intake manifolds (especially aftermarket ones) still have a port up near the thermostat. Just be aware that the #1513321 sending unit has 1/2" NPT threads and the ports in some intakes & late 70's cylinder heads are smaller 3/8" NPT. I have seen posts on here where folks have turned the 1/2" sending units down and re-threaded them to 3/8" to get around that issue if necessary.

Finally, this particular sending unit has a "nail head" terminal that works with a Packard/Delphi 56-series terminal and a special slotted plastic connector shell that allows it to slide on sideways.