low coolant temp reading

[mytrplseven]

My coolant gauge shows around 75 C after running for several minutes on a warm day. I'm wondering if air bubble in the cooling system could cause this. The water pump and thermostat are new, the belts are new and the coolant has been replaced. Anyone have any info on this?

[djnolan]

Measure the engine temperature near the sensor with a infrared thermometer to see if it agrees with the gauge. If the gauge is off, one way to correct is to gently twist the needle on the shaft. Is this a new problem or one that has been there a while?

[Pauld_94S2]

If your water temperature gauge is around the first mark from the bottom, then you are perfect!

Typically, if the engine is low on coolant, at idle it will quickly climb up the gauge to the red area, then drop when the engine is revved 2500-3000 RPM from idle. This is because higher RPM's get the coolant flowing and the radiator gets enough coolant to cool it before returning to the engine.

Another way to tell if you are low on coolant is to turn on the heater while the engine is at idle. If you gently and slowly raise the engine RPM and hear a gurgling sound from under the dash that's air and coolant circulating through the heater core. You won't hear anything if there isn't any air in the system.

[mytrplseven]

Since the car has been on jack stands for almost 5 years while doing the restoration, I haven't had the opportunity to run the engine for extended times. I'll put the thermometer on it to see where it is. Good info, thanks. I never had one of my previous 944's do this. One of my ref sensors went bad so waiting for a replacement so I can install it and run the engine again. Always something, right?

[mytrplseven]

I got out my lazer temp scanner and compared the temp readings to the gauge and was amazed at how good my car is cooling. I guess flushing the system and replacing the water pump and thermostat and temp sensor during the restoration made a huge difference from when I bought the project car. Following replacement of the A\C compressor and dryer plus a couple of hoses, I had the system evacuated and recharged yesterday. Getting a solid 43 degrees F out of the vents and no leaks. It's been a good couple of days.