Pyrometer/EGT gauge: Are the K-probes all the same?

[cattlerepairman]

I have a Westach EGT gauge; worked fine for years. Then it stopped showing EGT/showed them sporadically. I put in a new K-probe. Now it does show temps, but ridiculously low (400 F) on uphill grades where it should get to 1000 or slightly above.

Are there different types of K-probes and how would one know which one is which? Perhaps the gauge itself is defective?

 

[rustystud]

I have a Westach EGT gauge; worked fine for years. Then it stopped showing EGT/showed them sporadically. I put in a new K-probe. Now it does show temps, but ridiculously low (400 F) on uphill grades where it should get to 1000 or slightly above.

Are there different types of K-probes and how would one know which one is which? Perhaps the gauge itself is defective?

They have different "impedances" (resistance) . You must match up the correct one for the gauge to read correctly.

 

[cattlerepairman]

Thanks, rusty. I found some reference here: http://thesensorconnection.com/cont...type-k-j-and-n-usa-and-international-iec-5843
However, at least to me it seems that if a probe is a certain type, e.g. a "K" probe, it should work with other "K" calibrated gauges. Time to dig up the "defective" probe from the garbage and compare impedances.....and trace the probe wires because, knowing my truck, it could be something wildly unrelated, like a rat that stepped onto a circuit breaker, flinched and nicked a probe wire.

 

[Isawfrizzy]

Are you sure you didn't hook it up with the polarity reversed? Doing this will result in a low reading. Red is negative, couterintuitive.

 

[cattlerepairman]

No. Hooked up right. Contacting Westach.