| len47merc | -- 09-05-2016 @ 5:26 AM |
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For those of you that have used IR thermometers to check head temperatures on our V8s, what kind of results did you see and how consistent along the length of the heads - front to back - were those results? And if you know, how did those results compare to the known water temperature (or the IR reading at the water pump)? Just curious - thanks - Steve
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| trjford8 | -- 09-05-2016 @ 7:58 AM |
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There is some difference in readings between the gauge and the infrared thermometer. The infrared will read a little cooler than the gauge. The gauge is reading the coolant and the infrared is reading the outside metal and the air around it.
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| len47merc | -- 09-05-2016 @ 2:37 PM |
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Thanks - I was trying not to bias any replies that may have come but I'll go ahead with the background. I was given one of these IR touchless thermometers as a gift and was surprised in two ways to see the readings obtained from a fully warmed-up flathead. First, the IR thermometer showed head temperature readings sometimes well above that of a calibrated thermocouple & Fluke meter measuring the coolant temp. Secondly, the head temps varied significantly (and consistently side-to-side) from cylinders 1 & 5 (closest to the water pumps) to 4 & 8 (furthest from the water pumps). No concerns here, just odd observations and I was curious to see if others were seeing the same results. I've seen several discussion threads touting the use of these IR thermometers while my results lead me to question their effectiveness and usefulness for flathead/engine applications (other than thumb-to-the-horizon identification of potential hot-spots). Steve This message was edited by len47merc on 9-5-16 @ 2:39 PM
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| TomO | -- 09-06-2016 @ 8:34 AM |
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I use the infra red thermometer to check the temperature where the coolant enters and leaves the radiator. It is a good quick reference of how the radiator is working. The readings on the digital thermometers will vary considerably with the distance from the heat source, so you need to be consist ant with how far you are measuring. Tom
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| len47merc | -- 09-06-2016 @ 11:21 AM |
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Thanks Tom. My thermometer has an optimum measurement distance of a bit over 14" so I have been trying to maintain that consistently with each reading. What in your opinion and experience, with respect to incoming versus outgoing radiator coolant temp variance, represents a healthy radiator and 'like-new' performance for our V8s? 10, 15, 20, 25... degrees? Steve
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| TomO | -- 09-07-2016 @ 7:58 AM |
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I get 18 degrees from top to bottom on my Lincoln and it never overheats. I drove it to Kalamazoo, MI in August with outside temps in the mid 90s. We drove 65-70 and when I pulled off the road at the hotel, it was still in the middle of the range about 180. My Merc radiator shows a drop of 16 degrees from top to bottom on both sides, but will overheat if left to idle for more than 10 minutes or if I get stuck in traffic after driving a long distance on the expressway. Tom
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| len47merc | -- 09-07-2016 @ 12:32 PM |
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Thanks Tom - that's a great benchmark for me to look at. I am flushing/changing the coolant this week for the first time in 2+ years and will post the '47's temp variance results when through. Thanks for your reply. I know we have two different animals, but for what it's worth the '47's 59AB with 177 (or 155) thermostats and a 67/33 distilled/EG mix (and knock on wood here) runs cooler in 95+ ambient temps at extended idle (~180-185) than it does at 60 mph/2,500 rpm (~190-195). The validated 195 reading shows as slightly more than 1/2 way from the 3/4 mark to the 'H' mark on the gauge, the 185 about a 1/4 of the way or so. Perhaps my timing is a bit fast but I'm not hearing any pinging. Interesting with these IR units to see (and understandably so) how much cooler the front head cylinder temps are than the rear. Btw - the local radiator shop indicated to me that the IR thermometers should not be used on rubber or vinyl - only metal - to obtain accurate readings. I have not validated their representation technically but did note a variance in temp when reading the radiator hose beside the clamp versus the radiator metal and water pump metal just off the end of the hoses. Steve
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| 40cpe | -- 09-07-2016 @ 5:26 PM |
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I read a long time ago that they won't read correctly on bare aluminum, you have to paint the aluminum to get a good reading. That has been my experience. Your mileage may vary.
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