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Discussion Starter #1
I have several. Wondering how accurate they are for measuring coolant Temp before I pull the sensor and test it in some hot water. Seem to get around 185-190 on the intake manifold and am wondering if that if within a few degrees of actual coolant temp. Everything is new including the New Vintage cluster.

Any thoughts or comments?


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I have a Fluke I got on Amazon, I use it for powder coating. It was about $80, it's within about 5 to 7 degrees at 400º. The more you spend on these things, the better the accuracy. I tested it against a $300 gun that my HVAC guy has.
 

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Discussion Starter #3
I have a Fluke I got on Amazon, I use it for powder coating. It was about $80, it's within about 5 to 7 degrees at 400º. The more you spend on these things, the better the accuracy. I tested it against a $300 gun that my HVAC guy has.

Thanks, I have a Fluke and a Harbor Freight and they read the same:grin2:. More wondering if a reading on the intake manifold or thermostat housing would be close to actual coolant temp.
 

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I know mine is accurate because I used to have it certified to be in calibration every year. Mine is a Blue Point.

Is there a problem that you are trying to fix? If so what is it?


I have several. Wondering how accurate they are for measuring coolant Temp before I pull the sensor and test it in some hot water. Seem to get around 185-190 on the intake manifold and am wondering if that if within a few degrees of actual coolant temp. Everything is new including the New Vintage cluster.

Any thoughts or comments?


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Discussion Starter #5 (Edited)
New temp gauge is way off, like 25-30 degrees. I was going to pull the coolant temp sensor and test it in a pot of water but figured if I could at least quickly confirm how much it is off. Laser says 195 gauge says 225. Car runs great. Temp goes up a bit with AC on and slow traffic. Cluster says 235 but I'm guessing more like 200-205.


I see you have a red 68 XR7. My dad had one when I was 5 or 6 years old. I loved that car. I remember he got hit in the rear tail lights multiple times and those replacements were NOT cheap!
 

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Thanks, I have a Fluke and a Harbor Freight and they read the same:grin2:. More wondering if a reading on the intake manifold or thermostat housing would be close to actual coolant temp.
Have you found a need to adjust the emissivity setting on your HF temp gun?

Thanks.

Rusty
 

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Discussion Starter #8
Have you found a need to adjust the emissivity setting on your HF temp gun?

Thanks.

Rusty

Don't even know what that is :)


Thermometer reliable and accurate. Brian

Yes but after the thermostat. Probably the same if open and flowing. Think I'll just test my temp sensor and add a resistor if necessary.
 

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Don't even know what that is :) .
It’s an adjustment that is used when measuring different types of material. Depending on the characteristics of the base material the ir can return a value that isn’t accurate for the material and conditions under test. To answer the question I use a different setting between al and cast iron or cast steel.

Check this out. https://www.thermoworks.com/emissivity-table

After using a thermal imager for a while and a cheap gun I got a good gun off the truck. I find if I measure a hose or the top of the sender. Depending on where I measure the temp on the manifold it can return different readings. The gun measures the surface temp of what it’s pointed at and necessarily the coolant temp. With some poking around taking measurements and comparing you can do ok with just a gun.
 

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I took a class for CEU'S on infrared use. The field on those hand held guns is a cone. The farther away, the bigger the field it's reading and it only reads the hottest slot, not what the little red dot is on. The other is what @vegasloki said. Different materials, colors and textures reflect infrared back differently. Basically for as many different items all at the same temperature, you could get as many different readings.
 

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And the cheap guns don't have emissivity adjustments. Factory set they will give lousy results on shiny metal like that polished aluminum radiator. Pointed at painted surfaces they give a pretty accurate reading.

I would point it at the manifold right behind the thermostat. Pointing it at one of the air passages in the manifold won't be as accurate. Unless you have a polished manifold or one that has been jet hot coated silver. :)
 

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I used my Harbor Freight gun for the first time the other day. I started my '66 for the first time in awhile and it was missing. I have dual exhaust and could hear it coming from the driver's side. I shut it down and checked the temperature on each header on that side; #8 was at least 20-30 degrees lower than the others.

I realize things other than ignition could be the culprit, but I suspected the ignition wire for that cylinder, since I had unplugged it and moved it out of the way several times while working on the brake m/c and booster. I measured the resistance of it and several others with my ohmmeter. "Normal" seemed to be around 90 ohms; that one was 140. I've ordered a new wire set.
 

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In training to use a Fluke IR camera, the instructor told us, "if you're looking at a stainless steel panel and in the image screen, you see a guy holding a IR camera, you're not getting an accurate measurement."

Water and various metals will give funky readings, at times.
 

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In training to use a Fluke IR camera, the instructor told us, "if you're looking at a stainless steel panel and in the image screen, you see a guy holding a IR camera, you're not getting an accurate measurement."
The imagers are handy but come at a cost. For some applications an IR gun is a better solution. For example if I’m annealing, hardening or doing a weld pre heat on a surface and I’m using the proper gun with adjustments it’s a better application for a gun than imager. Same with powder coating. The more complex temp signatures require the imager. I sold my imager a while back as I wasn’t using it much but there are many things it can read that the gun doesn’t do as well or at all. I’ll probably pick up another imager but this time go with something like a phone based Flir than the Snap On I had before. Fluke has a good one around $500 as well but for what I (and most of us) do the $200 camera add on is probably a better value.
 

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I used my Harbor Freight gun for the first time the other day. I started my '66 for the first time in awhile and it was missing. I have dual exhaust and could hear it coming from the driver's side. I shut it down and checked the temperature on each header on that side; #8 was at least 20-30 degrees lower than the others.

I realize things other than ignition could be the culprit, but I suspected the ignition wire for that cylinder, since I had unplugged it and moved it out of the way several times while working on the brake m/c and booster. I measured the resistance of it and several others with my ohmmeter. "Normal" seemed to be around 90 ohms; that one was 140. I've ordered a new wire set.
Nice detective work there !:thumbsup:
 

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To elaborate, a flat black surface is ideal for IR temperature readings (Black body surface). The further from that you get, the less accurate the reading. Shiny or reflective surfaces are the worst, to the point of giving useless readings.
 

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New temp gauge is way off, like 25-30 degrees. I was going to pull the coolant temp sensor and test it in a pot of water but figured if I could at least quickly confirm how much it is off. Laser says 195 gauge says 225. Car runs great. Temp goes up a bit with AC on and slow traffic. Cluster says 235 but I'm guessing more like 200-205.
If you also used a new sender, it may be the source of the problem. All replacement senders, regardless of brand, operate in incorrect Ω range.
 

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The imagers are handy but come at a cost. For some applications an IR gun is a better solution. For example if I’m annealing, hardening or doing a weld pre heat on a surface and I’m using the proper gun with adjustments it’s a better application for a gun than imager. Same with powder coating. The more complex temp signatures require the imager. I sold my imager a while back as I wasn’t using it much but there are many things it can read that the gun doesn’t do as well or at all. I’ll probably pick up another imager but this time go with something like a phone based Flir than the Snap On I had before. Fluke has a good one around $500 as well but for what I (and most of us) do the $200 camera add on is probably a better value.
We use ours primarily for shooting the entire side of a machine. Hot spots can be easily located. Also, images can be saved and compared to later tests to detect increasing temps in the equipment.
 

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Discussion Starter #19
If you also used a new sender, it may be the source of the problem. All replacement senders, regardless of brand, operate in incorrect Ω range.

Interesting. Yes I used a new sensor. I have the ohm targets for 4 temps from the gauge manufacturer. I'm curious how far off it may be.

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