My 1970 455 GS Started running hot

Hopefully it is a cheap and/or an easy fix.

 

Is it a mechanical or electrical temperature gauge? If it's electrical, perhaps the car is still running at the correct temp and due to an electrical change the gauge is reading wrong?

Bob's idea about having an infrared thermometer is smart also.

 

Max,
Yes I considered a gauge issue but didn't seem as probable. I ordered an IR thermometer. We'll see if the gauge is telling the truth in a few days.
Thanks for all the help!

 

Your stat is stuck.....

 

It's a new stat and did the same thing as the old stat.

 

Very first thing I would do before throwing money at the problem is verify the gauge.

 

Yes I plan on it when the IR Thermometer arrives.

 

This is how I met my first wife. Yeah, really. Should have paid attention to the message karma was sending.
Anyway, She brought her car in because it would overheat pretty severely and pretty quickly. Went through FOUR brand new, out of the box thermostats to get one that worked. New isn't necessarily good.

Let us know what happens with that thermometer.

 

I always test them on the stovetop with a candy thermometer before installing them...

 

I also do that..... Ive had them fail once installed. remove Tstat back in the stovetop works.. reinstall fail... remove run without All good.

 

Well I put in an acdelco temp sensor to be sure that wasn't the issue and I wanted an oem one instead of what was in it. Temp gauge still read 230 deg.
My new temp gun said 170 deg at the sensor. Upper hose was at 180 deg and lower hose at 125 deg. Looks like my aftermarket gauge went south.
Doesn't matter as long as I know car isn't heating. I am going to get rid of those gauges in the future and reconnecting oem gauges in the dash.
Thanks again for all your help!!

 

Infrared thermometers are great tools, I have a couple, cause I used to rep a company that made them (Fluke). One thing you want to keep in mind to get accurate temperature measurements with them, don't try to measure anything that is really shiny, like polished aluminum, chrome, or glass. Black surfaces are the best. Bare aluminum and steel are touchy too. Shiny stuff has a lower emissivity value (radiates heat differently) which skews the readings.

https://www.merriam-webster.com/dictionary/emissivity

I'm also trained as a level 1 thermographer...

 

Good to know Rich thanks!

 

Some of the units actually have an adjustable emisivity setting for just the above reason.

 

I'll check. I doubt this one has any adjustments.

 

I saw those... What a joke..... How does one calibrate one? I got weights in all sizes grams, pounds. they dont change weight more or less day by day or hour by hour.... I dont know of a anything that is always the same temp....

 

Most of the ones I've seen, sold for automotive applications, don't have the adjustable emissivity feature.

On the units with the adjustable emissivity, the simplest way to calibrate one is by comparison and it would be specific to the area being measured. Put a piece of black tape on one part of the item to measure, take the temperature after a few minutes. Then take the temperature of an area close to the tape, and lower the emissivity value until the temperature matches that of the part with the tape. You can look up an emissivity table on the web, too. That would get you in the ballpark.

I wouldn't get too caught up in the exact temperatures, though. For automotive applications, most people don't want to take the time to do this, and for troubleshooting, the exact correct temperature is usually irrelevant. It's all about comparison, like comparing the measured temperatures across a radiator to find cooler or hotter spots, or checking header tubes to see which one is cooler or hotter (to find a miss or lean issue), or measuring the temperature of an AC vent (colored plastic ones) to get an idea of the outlet temperature of the air.

Another thing that is pretty important is the distance to spot size ratio (D:S) of the IR thermometer. If it is 4:1, then if you are 4" away, the spot size the unit is measuring is 1". The unit will show the average temperature within that spot size. Most have a minimum spot size as well. Keep this in mind when you are targeting the part to be measured.

I think 4:1 is probably the most common D:S for the inexpensive ones (under $100). I know that they have come way down in price since I sold them last.