The temperature gauge on my 1980 240GL has, for a very long time, read at about the 60% point of the gauge. That is, the needle pointed to a point a little higher than the mid-point. Suddenly, it has been reading even higher than that at a point just shy of the red zone. When I start the car up, it quickly rises to that point and then is steady with only very slight movement. It is still in the green zone, but not by much at all.

I am not sure if the problem is with the gauge or with the actual temperature of my car's engine.

I am NOT mechanically inclined and do NOT understand any of the lingo about engines. Can someone tell me (1) using the numbers on this photo, at which point I should use a laser temperature tool to measure the temperature and (2) what the temperature should be at that point?

 

You should use none of those on that side of the engine/radiator. Use you laser gun on the thermostat housing, as the water is leaving the engine going to the radiator. There or on the head near the thermostat the temp should be near the installed thermostat temperature, (160-180-190)

I see you have a relatively new radiator ( I would use a zip tie through the radiator core to make sure the plastic plug for the temp sensor you don't have does not pop out) And you have a manual transmission. And dude - there's no hose connected to your washer pump!

A 1980 does not have a temperature compensation board that makes the temp gauge lie or give inaccurate readings - so - remove your thermostat and make sure it is not broken and sticking partially open/closed. The operating temp is usually stamped on it somewhere.

The temp sensor is located under the intake manifold with a single xx colored wire - and do sometimes go bad - although it's a simple thermistor - they are very reliable. A 1980 has the old style voltage stabilizer on the back of the instrument cluster. Those were prone to failure. They are mechanical versus electronic in the 1986 + cars. The voltage stabilizer was supposed to provide a constant voltage to the temp and gas gauge to make them accurate, for the voltage fluctuates from say 10 to 14.5 volts in your car.

https://www.skandix.de/en/spare-part...lizer/1021371/

 

I don't know what any of what means unfortunately. I'm just going to have my car towed to the shop.

 

OK if it's not overheating just drive it.

 

check if its low on water.