temp gauge reading high

[resq302]

What would cause the temp gauge to read about 20-30 degrees higher than normal?  I just put an NOS temp sending unit in and it did not correct the problem.  I took a infared thermometer to the area of the temp sending unit and it was reading 188-190 yet the gauge was reading almost 230.  I know the gauge works off of resistance but could a gauge just start reading inaccurately or would you say there is some other issue going on?

[Back N Black]

The gauges are adjustable, there is two small holes at the back of the gauge. unfortunately you have to remove the gauge.

[resq302]

Ah, ok, I was not aware of that.  Thanks!   

[Back N Black]

 Here is a pic of the holes in the gauge for adjustment. The serated teeth on the gauge arms are used for calibration. Thats how to get the gauges in tune.

[resq302]

Wow.  Thanks, I never knew that.  Good to know.  I wonder if the rattling / vibration from driving worked its way loose or out of adjustment over time?   

[PlainfieldCharger]

Mine is doing exactly the same thing. Same temp readings on both the gauge and thermostate housing. I guess my cluster is coming out. How do I adjust it when it not hooked up?

[oldcarnut]

Just for curiosity or verification did you try an aftermarket gauge to compare readings?

[resq302]

Me, no.  However, I highly doubt the infrared thermometer would be wrong or off by that much.

[PlainfieldCharger]

I also used an IR Gun. I have a new "OEM" gauge though...I am looking at my old one which worked but the face was faded. Still do not know which "hole" adjusts the high end? Do both do the same by adjusting the resistance and are used in together?

[Back N Black]

Its a long read but great info. in link below

http://www.dodgecharger.com/forum/index.php/topic,37999.0.html

[Pete in NH]

HI,

The link referenced in the last post is a really excellent write up on checking out cluster gauges. Making up the little test box mentioned out of Radio Shack parts is the way to go and duplicated the original Chrysler test box for these gauges. The only other thing you need as referenced in the write up is a source of regulated 5 volts DC. For bench testing you can make up one of those 7805 instrument cluster regulators on a good heat sink and power it from a 12 volt battery. If you need help with that let me know.