Hot cylinder head/gauge problem fixed

[NAM VET]

I thought I would summarize my (non-existent) problem in a new post. My M37's rebuilt engine always read about 210 degrees on the older, original style gage. The gauge had a bit of jiggle to the needle too. I watched and worried for some thousands of miles about my "hot" motor, when with a rebuild including hot tanking and a new distribution tube, how could it run hot to the rear of the cylinder head. I used an infra-red heat gun and at first thought my head was indeed 210 or so at the rear of the head, but with more accurate testing, it was actually near my T Stat's 180 degrees. So called Chales T and he suggested replacing both the sender and the gauge, but the Douglas connector sending units and gauges are long gone, and if you use an early sender with a late gauge, they give inaccurate readings. Plus, others had suggested that old units could be just out of spec.

Charles T sent me a new sender and gauge, the newer Packard ones, with a plastic clear gauge case. So drained some of the antifreeze, and moved the oil filter out of the way, and put in the new Packard sender, and installed the new gauge, and made up with left over Douglas and Packard connectors, a new line to the gauge, spicing in a WeatherPack quick disconnect. The sending wire to the gauge is #33, and with a new Packard connector, wired the sender into the ribbed rubber female connector on the gauge. Then, made a short line to splice into the hot lead, #27, with a new Douglass on one end, and a Packard on the end to the smooth rubber connector on the gauge.

Cleaned up a few wires under the dash, and started my truck, and at fast idle it gradually rose to about 160, then went out in our 95 degree day here in UpState SC, and the temp on the gage rose to about 170, and not hotter. The new gauge has a different face and numerals than the old ones, the new one reads 120-160-200-240, and my final hot operating temp got up only to about 170 or so, and never warmer.

So I worried for nothing, and my engine never did run hot. Accurate instrumentation is always important, and I have that now.

Finally, peace of mind!!!

And thanks to all of you with your suggestions and observations, and of course to Charles T for his guidance.

NV. (aka Hal Copple)