Pyrometer Readings

[CROW]

The last time I towed my fifth wheel I noticed that the temperatures shown on my pyrometer were lower than usual by 100 to 200 degrees. Unit is an Auto Meter Ultra Lite that I installed in Oct., 2007. Other than checking the connections I cannot think of anything to do. The probe is mounted in the hole provided by the Jacobs exhaust brake.

Any thoughts on what I might do to check this out?
Thanks in advance

 

[p-Bar]

Only way is to pull it and check it against a known calibrated one

 

[Bob4x4]

The thermocouple can be tested,there are charts that can be found online showing values vs temps

 

[User113]

A thermocouple is a very simple device, namely two different metals welded together. The magic happens at the junction of the dissimilar metals. However, over time and due to the intense heat, the junction can become diffuse, reducing its effectiveness. There is also the possibility of a bad connection in the wiring due to corrosion or mechanical degradation, a break in the insulation causing wire to contact the metal housing or braid and introducing an extraneous dissimilar junction, or there may be a problem in the electronics that is reading thermocouple. My money would be on the thermocouple itself.

First, I would take the thermocoule out and inspect the tip for cracks, pinholes, etc. The probe tip should be structurally sound. If it is otherwise, you have probably found the reason. If it is sound, however, you may still want to replace the probe with new one. Thermocouples come in standard types, set out by ANSI. You can tell the type by the standardized wires. If the wires are red and yellow, it is an ANSI type K thermocouple. Should be easy to find a replacement; you shouldn't need to buy a new gauge.

For example:

Bully Dog at Advance

Generic on ebay

 

[CROW]

Thanks to all. I now have a starting place to start trouble shooting.