Failed oil temp sensor? Another one erratic.

[CheckerBird]

Been running the D-120 EMS on a Lyc IO-360 for a little over a year and 175 hours now. On the way back from Oshkosh, the oil temps started jumping erratically back and forth between the normal (~190) and about 133-134 degrees. For a little while is bounced back and forth between 133 and 155 degrees, then, back down to 133 where it stayed for the rest of the flight. After landing I used a handheld laser/IR thermometer on the oil filter and it said 190 degrees, so the engine temps were steady and normal the whole flight. I checked the wiring and engine ground and all that checks out with a digital ohmmeter to be perfect. No other sensor issues either. Has my oil temp sensor just failed? Is this a common failure?

Also, since the sensor body is brass, would it hurt it to solder a ground wire to the body?

 

[jakej]

I have seen this symptom before - The simplest check is with the crimped terminal onto the sensor, see if the wire is moving inside it as sometimes you can get a poor crimp. Soldering the wire will make it more a more solid connection.

Jake J

 

[CheckerBird]

Went back out to the airport today and checked the wiring once again and found exactly just that... a poor crimp on the ring terminal.  Since the wire is so small (22 or 24 gauge) it doesn't fit very tight inside a red crimp terminal. I doubled the wire inside the terminal and crimped on a new one, plus I soldered it also. I also soldered a ground wire onto the brass body, it soldered quite easily and I didn't have to heat up the body very much at all. I had to do some fiberglass work on the top cowl, so I didn't get to fly it to see if the fix is permanent, but will fly it next weekend. Powering it up showed the oil temp to be 100 degrees sitting in the hangar, our ambient OAT here in Texas right now is 102 which makes the temperature inside the hot metal hangar probably approaching 110 by now.

 

[CheckerBird]

Well, two flights later it's doing it again

I'm positive the wiring is all solidly connected, with no intermittent connections anywhere.

Gonna order a new sensor next week and try a replacement to see if that solves the problem.

 

[jakej]

What a pain for you It's hard to troubleshoot these types of faults over the net however I'm confident you'll find the problem, stick with it.

Jake J

 

[CheckerBird]

New sensor is installed... oil temp readings are stable and normal now. It must have been the sensor itself.

 

[jakej]

Good to hear it's sorted, that's a relief for you. Happy flying ;D

Jake J