I don't know for sure what the protocol is around this here shop but I'm posting in this string instead of starting a new one. Somebody'll square me away if I need it, I suppose!
Anyhow, I was/am having a similar problem as super250six with my 58 Apache (283 cid). Rebuilt engine, new water pump, new radiator, new thermostat, new sensor, hoses, etc. Same fan as before I pulled the engine. I don't have the exhaust bolted up beyond the headers.
Initially I'd start it up and it would idle for about 3-5 minutes and the temp gage would drive right up to max. (original gage so not a particularly precise instrument).
I set/re-checked the timing and went down thru the litany of troubleshooting suggestions posted in earlier this string. No joy. Still pegging the temp gage after idling a few minutes.
I pulled the newly installed thermostat and discovered that I had a 195 deg. thermostat - musta been boxed incorrectly or returned to the parts store or something. I swapped the 195 for a new 160 deg. thermostat and that definately helped some.
However, after about 15 - 20 minutes idling in my driveway, the gage went to the max again! While the engine is running up at idle I can watch the temp gage & see when the thermostat opens up (a bit past halfway on the gage). The gage drops, stablizes for awhile then starts rising again.
What else can I check? How do these temp sending units work? Should I buy a calibrated gage to hook to the sender & see what the temperature really is? Is there such an instrument? Can I test or calibrate the temp gage (it's the original)?
I'm going to drive it around the block tomorrow to see if the temp (or rather temp gage) stablizes at a lower level when moving or not. I expect it will but how's the booger gonna act in stop & go traffic?
Anyhow, I hope enuff folks are still wired to this string to help. I'd get mighty bent if I fried the new engine! Red58 might hear me screamin clear up in glacier valley!
