Coolant Temp Sensor Readings

[jsr6683]

I have a Rotax 912ULS (suffix-01) and a SkyView HDX in a new build. The Rotax supplied coolant temp sensors read about 25 degF and 35 DegF higher than the cylinder head temps but are reading within a few degrees or so of one another. I measured actual CHT's after runup to operating temp using a digital infrared thermometer/gun and they look okay. Sensor excitation voltages are okay at 5V. I don't know where the GND reference is for these sensors, but want to check that too. Are the Dynon sensors substitutes for the Rotax sensors in case I need to replace them? Thanks!

 

[Dynon]

So ALL of those sensors (CHT/coolant/oil temp) on the 912 are Rotax-supplied parts that we connect to. And unless things have changed, I think they're all the same exact sensors. I also thought that there were ONLY water temp sensors and not CHTs (or at least that's what they call them).

 

[jsr6683]

The temp and coolant sensors are the same. And yes, there are no CHT sensors on a newer suffix-01 912 engine. My coolant sensors read WAY too high on the EMS, but the oil temp reads correctly. I'm still searching for a possible explanation for it. Often it's blamed on a lack of a good common airplane ground system, which isn't the problem in my case. The sensors are single wire with 5V excitation. Will measure the sensor resistance and report back on findings here.

 

[CarlosQ]

Hello. What do I need to change in the HDX if I changed and old 912ULS with the old cylinder heads for the a new one with the suffix -01 heads? CHT to coolant temp.
thanks