test the overtemp sensor

[MartyH]

I can clearly see that the red oil pressure warning light and sender work fine (after I wired it up!). Is there a simple way of testing the overtemp sender and light? I was thinking about removing the sensor and puting a heatgun to it. I need to flush and fill the radiator anyhow. I don't KNOW that the dealer put 30% antifreeze in it.

 

[JohnMiller3]

<font color=blue>…Is there a simple way of testing the overtemp sender and light?...</font color=blue>

Most of these units are encapsulated “thermistors” (variable thermal resistors that change with temp change) that will show some resistance/continuity. (high resistance when cold/ low resistance when hot)

A quick test to check the temp circuit or determine a faulty sensor is remove the plug/wiring going to it… insert a jumper wire across the plug (lowest resistance), your temp gauge will peg full “HOT” or the temperature warning lamp will illuminate…

You can go through the motions of removing the sensor, submerging it in water, hooking up an ohmmeter across the sensor terminals, and heat up the water… as the temp of the water raises…you will see a “decrease” in resistance with your ohmmeter.

As a rule, you normally don’t have “wiring failures” (unless you ripped it with a stick while brush hogging /w3tcompact/icons/blush.gif), you usually have open lamps, open sensors, or a defective temp gauge…

Good luck with your diagnosis… /w3tcompact/icons/smile.gif

 

[HoyeTractor]

Better yet, ditch that light and put in a gauge. Every time I get on a tractor that has only a temp light I wonder if it is really working. It's just not worth the risk (to me). If you have the dash space (or don't mind sticking one on top), replace the light with a gauge and you'll know for sure.

 

[TWINKLE_TOES]

John,

He has a "light" not a gauge. It's a thermal switch not a thermistor.

 

[JohnMiller3]

Thanks Al... /w3tcompact/icons/smile.gif

I better slow down a little when I read these things.../w3tcompact/icons/blush.gif

I may cause somebody split a tractor to change a light bulb... /w3tcompact/icons/laugh.gif

 

[normde2001]

Don't fall on your sword yet, John. I believe you said <font color=blue>...your temp gauge will peg full “HOT” or the temperature warning lamp will illuminate…</font color=blue>and the test is the same except you close a switch instead of lowering resistance.

 

[Inspector507]

You Big 3 guys gotta split your tractor to change a bulb...??


/w3tcompact/icons/laugh.gif/w3tcompact/icons/laugh.gif/w3tcompact/icons/laugh.gif
Just teasing............

Jerry

 

[TWINKLE_TOES]

John,
I have always learned more by doing things wrong than right.
Al

 

[JohnMiller3]

/w3tcompact/icons/smile.gif

<font color=blue>...always learned more by doing things wrong than right...</font color=blue>

Isn't that typical with being on a farm or just being a plain kid...? /w3tcompact/icons/wink.gif

When you're younger, Dad would always pay for our mistakes...

Then ya get older, and have to foot the bill yourself...(Ouch!) (makes you appreciate Dad that much more...) /w3tcompact/icons/smile.gif

 

[JohnMiller3]

<font color=blue>...You Big 3 guys gotta split your tractor to change a...</font color=blue>

Well... /w3tcompact/icons/eyes.gif believe it or not, on the older Masseys... you had to split them to change the hydraulic pump... before external engine mounted... /w3tcompact/icons/blush.gif