Erratic oil temp readings

Hi Roger,

I a bit awkward asking this - but just to clarify, is it the oil temperature or the pressure which is erratic? (I've never seen temperature measured in PSI before)

If it is the pressure which is fluctuating, it would be helpful for troubleshooting to know if the sender is of the older resistive type or one of the newer 4-20 mA types. I believe that 2008 is about the time that Rotax changed to the newer type of oil pressure sender.

It is the oil temp. I should have done a better job reading my post before I posted it. I corrected my post.

I hate growing old. 😂

Hi Roger,

Assuming it’s a 912, the oil temp sensor/probe is the same as the one in the cylinder head (water jacket style coolant) have struck a couple of these that have given erratic readings as you describe, issue was intermittent which lead me to thinking it was a connection/wiring issue. after checking ever connection and wiring ruled out was forced to by some replacement sensors probe (Rotax p/n 965531) after changing out the sensors in both cases the erratic reading has gone away.

Bench testing the sensors showed them ok with an ohm meter, could only get one at ambient temp to show out of the correct range on one occasion, since changing the sensors no more erratic readings. If you have a spare sensor very easy to change out (don’t even need to drop the oil out)

In both cases the engines had experienced a genuine over temperature event due to other issues with their cooling systems, possible that the higher than normal temperatures have damaged the sensors, although I would expect these sensors to far exceed any temperature the engine might be expected to produce.

Regards,

Byron

Hi Byron,

912ULS in a 2007 Flight Design CTLS.

I tried switching the CHT and oil temp sensors. No change. Put in a new oil temp sensor no change, Tried 3 sensors and no change. Installed a new wire and connections from the probe to the Dynon. No change. Checked all the grounds. The engine has two solid grounds and the Dynon has two grounds. Used and Ohm on the senders and they were more or less the same. This hasn't been an issue on this plane for 1700+ hours and then out of nowhere popped up.

Long shot - Could the Dynon be implicated?😈