An issue has come up in my new toy, Abby, a 1968 145S I've had for 2 weeks. I noticed on the way home upon initial purchase that the temp gauge flirted with the red zone. Didn't think much of it at the time, those gauges can be weird.

Driving around this week, however, the issue got worse, and now the car will consistently run about 5 mm into the red zone continuously. Seems to get slightly hotter and idle, and slightly cooler at speed, but just a few mm, and always stays in the red. However, even idling forever doesn't make the gauge totally run away, and I never boiled best I could tell.

The car is new to me, and mostly unknown. Here's what I do know. New thermostat (unknown temperature), all new heater hoses, probably original radiator. Coolant looks good and clean, and no loss best I can tell.

I've scoured the boards here in order to amass the best knowledge base for this endeavor. Here's my to-do list so far.

1. Run the engine temp up. Measure the actual coolant temp. Make sure it really runs hot.
2. Take off all hoses and thermostat. Flush engine and radiator thoroughly.
3. Look for gunk specifically in the upper coolant pipe in the head like others have found.
4. Check thermostat and potentially replace with 180 degree unit if original is higher.
5. Fresh coolant, and run

I'm hoping I'll catch any clogs or find a clear culprit during this process that will explain the high temps. However, if they're not real to begin with after my temp test, I may have an electrical gremlin on my hands. Some evidence of this is that I find occasionally my fuel gauge and temp gauge will jump around randomly, like the level of gas is going up and down rapidly in the tank. I'm imagining this could be a bad ground, and perhaps is why the temp gauge reads high. I know that when full, the fuel gauge goes all the way off the scale to the right so that I can hardly see it, so that could mean that one is reading off too. Is there a quick and easy place to check the instrument cluster gauge ground? Do both those gauges share a common ground?

If there's anything else that needs to be on the list above, please chime in. Thanks!