Hello,

A couple of weeks ago I asked about an oil temp sensor issue with my IVP TSIO 550.  I took the prevailing advice that the sensor was unlikely to be the failure point and therefore followed out the connections, replacing the ones that were suspect and checking other connectors for contact.  Nothing I did improved the situation and in fact the oil temp readings I am getting now are beginning to interfere with flight because the temp reverts to 59 degrees when the temp gets around 90 degrees whereas it wasn’t happening until about 130 degrees or so – sometime after takeoff the first few times it occurred.  The current condition makes it difficult to assure that the temp is up to 120 degrees prior to takeoff.  This is the minimum oil temp I have been advised to take off with.

Today I tried a new experiment.  A little while after engine shut down the oil temp gauge was reading 59 degrees and I knew the oil was much warmer than that, so I tried disconnecting and reconnecting the wires where the probe attaches to a/c wiring.  That made no difference in the reading on the gauge, so I then tried manipulating the wire where it comes out of the sensor probe and the result was immediate – 85 degrees I think it was.

My conclusion is that it is the sensor and the wires coming out of the probe have been damaged, so I think I need a new sensor probe. 

I was given a sensor probe recently that appears to be new but has no markings on it that I can find.  I tried hooking it up and the resulting indication with warm or cold engine is about 300 degrees.  Same if I reverse the polarity. 

With the  existing sensor that I think is failing the oil temp reading never reads below 59 degrees.  In fact when I disconnect the wires, the reading is the same.  Is this normal?  I have the Grand Rapids EAU feeding Chelton MFDs and feeding Vertical Power. 

Looking in A/C Spruce I am not able to tell what sensor to purchase and I think that’s what I need.

Anyone have an answer?  TCM appears to be inaccessible unless you have an account with them?  Is there a way to get a response from them?

Thanks,
John