Water temp sensor readings
Thread Starter
Melting Slicks
Joined: Nov 2001
Posts: 2,659
Likes: 7
From: Katy (Houston) TX
CI 7-8 Veteran
Water temp sensor readings
I finally got the motor back in 
and let it just run for a little while, while I set the timing etc. Anywho, I didn't have the electric fans hooked up (running dual spals) and the water temp started climbing after a good 5 minutes or so. On my guage it was reading just over 200 but I have a lazer temp gun and I never saw anything over 150 on the gun. I shot it at the water neck, the sensor that is screwed into the water neck, the intake manifold and the radiator. I got anywhere from 120 to 150. The sensor is not in the heads because my Canfield's don't have a provision for one so I used another sensor that many here on the forum recommended that will fit in the water neck.
So I'm not sure if the sensor isn't reading or calibrated correctly or if you just can't accurately measure from the places I measured?
On the bright side the engine sounded awesome, even healthier than version I and it didn't smoke AT ALL!! There was a lot of blow by though but I'm starting another thread for that....
and let it just run for a little while, while I set the timing etc. Anywho, I didn't have the electric fans hooked up (running dual spals) and the water temp started climbing after a good 5 minutes or so. On my guage it was reading just over 200 but I have a lazer temp gun and I never saw anything over 150 on the gun. I shot it at the water neck, the sensor that is screwed into the water neck, the intake manifold and the radiator. I got anywhere from 120 to 150. The sensor is not in the heads because my Canfield's don't have a provision for one so I used another sensor that many here on the forum recommended that will fit in the water neck.So I'm not sure if the sensor isn't reading or calibrated correctly or if you just can't accurately measure from the places I measured?
On the bright side the engine sounded awesome, even healthier than version I and it didn't smoke AT ALL!! There was a lot of blow by though but I'm starting another thread for that....
Pro
Joined: Nov 2004
Posts: 659
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From: Flower Mound Texas
When you say water neck, do you mean the thermostat housing? I found this is the most reliable place to measure temperature with an IR gun. One thing to keep in mind - the IR guns produce inaccurate results when flashed onto shiny surfaces like chrome or aluminum. Best to flash it in a dull black or dark colored hard surface. Having said that, my new thermostat housing is bright orange / red and it works fine there. But I get a big difference when I flash it on my aluminum radiator or even the hoses. Back when I had the black brass-core radiator, the temp difference at the upper hose neck of the rad and the thermostat housing was about 3 degrees, so I considered it fairly reliable. Now with the aluminum radiator, the only reliable source with the IR gun, IMHO, is the thermostat housing.
Team Owner
Joined: Jul 2001
Posts: 182,997
Likes: 88
From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
Originally Posted by Razorhorn
I found this is the most reliable place to measure temperature with an IR gun.
Thread Starter
Melting Slicks
Joined: Nov 2001
Posts: 2,659
Likes: 7
From: Katy (Houston) TX
CI 7-8 Veteran
Hmm, well my thermostat housing is chrome, hoses are chrome, and radiator aluminum. But the sensor is brass and the reading was approx the same from it.
Unless the readings still aren't accurate, it looks like my sensor isn't calibrated properly to my guage.
Unless the readings still aren't accurate, it looks like my sensor isn't calibrated properly to my guage.
C6 the C5 of tomorrow
Joined: Nov 2000
Posts: 6,665
Likes: 2
From: Twin Cities Minnesota
Ir guns are known to be inaccurate and need to be adjusted for the emissivity of the measured surface. It's not just shiney vs dull, different materials have different emissivities and therefore apear to be different temperatures.
The best way is to paint the surface with high emissivity paint specifically for the purpose. Not typical black paint! also remember the thermal conductivity of the surface will affect the reading. Aluminum is best since it's low mass and conductive. Rubber is basically an insulator.
Another way to use a gun is just to look for changes. always use the same spot and compare before and after a cooling system change but remember it's all relative!
Use those guns with care and they are OK, but never as good as a good thermometer sitting in the water, mostly because you never know when they will give you the right reading...
I spent about 10 years in the R&D department of Minco Products doing temperature sensor research if you want to know if I know what I'm talking about
The best way is to paint the surface with high emissivity paint specifically for the purpose. Not typical black paint! also remember the thermal conductivity of the surface will affect the reading. Aluminum is best since it's low mass and conductive. Rubber is basically an insulator.
Another way to use a gun is just to look for changes. always use the same spot and compare before and after a cooling system change but remember it's all relative!
Use those guns with care and they are OK, but never as good as a good thermometer sitting in the water, mostly because you never know when they will give you the right reading...
I spent about 10 years in the R&D department of Minco Products doing temperature sensor research if you want to know if I know what I'm talking about
Team Owner
Joined: Jul 2001
Posts: 182,997
Likes: 88
From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
Originally Posted by tshort
Hmm, well my thermostat housing is chrome, hoses are chrome, and radiator aluminum. But the sensor is brass and the reading was approx the same from it.
Unless the readings still aren't accurate, it looks like my sensor isn't calibrated properly to my guage.
Unless the readings still aren't accurate, it looks like my sensor isn't calibrated properly to my guage.
