oil temp sensor resistance

Why note place it in the steam, just above the surface of boing water - consistent 100C, Sea Level and see what the reading is.

Sean Griffin wrote:

Why note place it in the steam, just above the surface of boing water - consistent 100C, Sea Level and see what the reading is.

Not least because I don't know what I'm doing :-)  That certainly isn't an ambient temp of 20C.  Does that matter, since the notice in the book says the graph is only valid at that point?

Of course, I can't get to sea level from where I am, either, but that seems the minor challenge.

Unless you live in one of the Worlds very high mountain ranges , don't worry too much about your height above sea level. The lower boiling point of water with increasing altitude, is unlikely to make a big difference to an engine coolant/oil sensor.

You will need

At least one helper, two better

To remove your sensor from the engine, reattach sensor lead (to your cockpit readout), firmly wrap a length, of bared, 12 V wire around sensor barrel - connect back to engine (this is your earth/ground return).

Switch on aircraft engine monitoring system

Use a pair of long nose pliers or tongs to hold the sensor (keep hands away from steam)

Bring a vigorously boiling kettle (best) or saucepan, close enough to enable sensor to be put into steam at kettle spout/just above saucepan surface of water.

Read instrument in cockpit - should indicate around 100C 

Note:

This is not about precise (100C) temperature on the gauge, only that the sensor/gauge is able to give an approximate/acceptable read out  at this temperature. 

An inaccurate reading could be either the sensor or the gauge - try a second sensor - same result? suggests gauge failure.

The VDO oil temp and CHT sensors are extremely resilient. In 20 years I have only replaced two. On one someone broke off the electrical connector and the other had the plastic melt from a broken exhaust pipe gas. All poor sensing issues I have run across have been from poor grounds, wire rubbed through on a metal surface, poor wire connections and the connection on the sensor was too loose. 

Hi there!

I got annoyed by oil temp readings over time and invested some time to measure the resistance curve of three sensors of the same type. My simple personal findings confirm that the sensors may give you a rough guess rather that the true temperature. 

Part of „the problem“ may be that we expect that the temp is x Celsius when the digital display reads x. Actually there are sensors in the market that read +/- 0.5% but not the VDO-sensors (or ROAD) used for Rotax 912. In the area we are interested in their accuracy is +/- 7-8% - which, in my opinion, is not close enough.

The ideal starting point for any problem solving activity is to determine the true temp with an accurate and reliable device. Knowing for sure that 130C indicated is 115 true temp would help to overcome the mentioned „part of the problem“.

;-)

Good luck!