Testing of Gauges

[RickH]

Can Anyone tell me the resistance readings I should expect if I test the various Temp sensors attached to the 582 rotax engine ie. EGT, CHT and water temp. Also would welcome comments on testing the gauges and sensors as well.

 

Example Water temp gauge on mine appeared to not be working so to test it I connected the power and earth pins to + & - on the battery and bridged between the earth wire and sensor terminal and the gauge went to full scale so I assume the gauge is working. I put a multimeter across the sensor wire and earth and got a reading but am unsure as to what the resistance of the sensor should be when cold.

 

RickH

 

 

[storchy neil]

rickh please tell me I read you wrong that you arked across battery

 

a jug of boiling water should do it place probes in boiling water

 

do not over titen probes when replaceing in engine and make sure that probes are insurted far enough in to engine

 

get rotax manual neil

 

 

[cscotthendry]

Rick:

 

Have a look at the VDO specs. I think that most Rotax engines use the VDO type temp senders.

 

http://www.vdo-instruments.com/media/instructions/TU00-0770-5104620%20Temperature%20Sensors_short_version.pdf

 

The document has the characteristics tables for all their senders. I think that Rotax use the 150dec C senders, at least thats what is on my 912S

 

 

[RickH]

Yeah Neil You read wrong the proceedure I described is pretty much standard for testing the guage. Think abuot how the gauge actually works. Rotax Manual dont mention resistance values.

 

Thanks heaps Scott I will check it out.

 

 

[cscotthendry]

Yeah Neil You read wrong the proceedure I described is pretty much standard for testing the guage. Think abuot how the gauge actually works. Rotax Manual dont mention resistance values.Thanks heaps Scott I will check it out.

Rick:

I just checked out a calibration run I did on my Aviasport CHT gauge and the values from the sender characteristic chart number 2 in the VDO specs tally very closely with what my gauge showed.

 

 

[RickH]

Thanks again Scott seems it is a power supply problem with the Water Temp gauge

 

Have not yet got to the bottom of CHT gauge probs will let you know how I fair.

 

To soon to tell if need a new gauge Deborah let you know.

 

 

[cscotthendry]

Rick:

 

On my engine the CHT is the temp gauge, I don't have a water temp gauge and the CHT is the same scale as what a water temp gauge would be anyway. I used a potentiometer and multimeter to calibrate the scale on my gauge. To test the sender, I put it in a pot of water on the stove and brought the water to boil (I live right at sea level so the boiling point is standard) and measured the resistance of the sender. Then I checked that with the value required to show 100 deg C on the gauge and they were similar. That was the only value I could check as I didn't have a thermometer to check any other temps with the sender. With the senders, it's just a, go - no go, check anyway, they either work or they're broken.

 

Also, if you look at the VDO charts for the senders, they show a lot of variations over the temp range so the readings from different senders will vary somewhat. Also, the model number of the sender is usually stamped on the hex head of the sender.