1966 Mustang spiking temp and oil pressure gauges

[Bucks]

Just wondering if anyone has had the same issue or has resolved it, i thought the mustang was getting hot sitting at idle today at the traffic lights, then i notice that at idle the oil pressure gauge and the temperature gauge are both rising and going to high at the same time.
Once you add some revs they both drop back to the proper readings, so assume some electrical earth problem at idle. (standard factory gauges) also only does it when the car is warmed up to full temp at idle or just above.

[188 LVU]

There's a thing called a " voltage regulator " behind the instrument fascia.  They can play up and cause all kinds of problems.  Is it actually getting hot or just the gauge telling you a story ?  Not expensive or difficult to replace if you have to.

Others may have better ideas.
PKJ

[Dwayne]

https://www.mustangtech.com.au/Content/pid=28.html

[GEOFF289]

Yep, sounds like a voltage or earthing issue to me.

[Bucks]

Thanks for the replies, sounds like the CVR is playing up with this warmer weather, the amp gauge has moved off the center in the last couple of weeks, then what i thought was getting hot wasn't and it never has before, I laser temped it this morning, running at 91 deg this morning with the gauge past the hot line at idle, as soon as you give it a few revs the temp and oil pressure drop back to where it normally runs. might attempt the jaycar fix above, might have to have a few practice runs on the soldering iron, have not used one for about 20 years.

[scollist]

I'm definitely not an expert here so take this with a grain of salt:

My understanding of the CVR is to drop the 12 volts down to 5 volts. The alternator when working well will actually deliver higher than 12V (somewhere around 12.8 to 13.2 to charge the battery as well.  Is it possible that the regulator is playing up and delivering higher than the 12V input? Therefore the problem isn't with the CVR but with alt/reg?  So I'd check the alt/reg first to be sure all is good there.

[Bucks]

Yes, this could be something as well, as the gauge for the alternator has moved off the center where it normally runs,
so will check the output from the alternator first, the battery when not running is showing fully charged at 12.8 volts after the car was switched off for over an hour, as i thought the battery may need charging.