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Rx7 S5 stock coolant gauge accuracy

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Old Jan 19, 2022 | 09:25 AM
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Rx7 S5 stock coolant gauge accuracy

Are the oem S5 water temperature gauges really this inaccurate? Maybe I still have air in the system? I was monitoring my water temperature on the laptop and around 170F the needle sits in the blue middle. When the needle reaches the green area it reads around 180-190. My low speed fan is set to come on at 180F and my high speed kicks in at 200F. Once the low speed fan kicks in the temp gradually drops back to the blue. I’m also monitoring with a Haltech water temperature sensor and an aftermarket gauge. I would like to hear other people’s opinion regarding the stock temperature gauge.



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Old Jan 19, 2022 | 09:36 AM
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From: https://www2.mazda.com/en/100th/
its not really opinion, the S5 gauge has three "zones" 0-65c its normal but damped. 70-100c the needle doesn't move, and then anything over 105c the needle moves and its not damped at all

i built a little tester, so i could use a potentiometer instead of the sender
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Old Jan 19, 2022 | 09:48 AM
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Originally Posted by j9fd3s
its not really opinion, the S5 gauge has three "zones" 0-65c its normal but damped. 70-100c the needle doesn't move, and then anything over 105c the needle moves and its not damped at all

i built a little tester, so i could use a potentiometer instead of the sender
Ok. So should I even pay attention to my stock gauge since I have two other ways of monitoring my temperature? I’m assuming the Haltech gm sensor is the most accurate since it goes straight to the computer.
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Old Jan 19, 2022 | 10:12 AM
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Originally Posted by Hygoog
Ok. So should I even pay attention to my stock gauge since I have two other ways of monitoring my temperature? I’m assuming the Haltech gm sensor is the most accurate since it goes straight to the computer.
Yours sounds off. Going by my Autometer gauge mine seems to function as j9fd3s describes. Once to operating temp it never moves from the blue area you have marked. I've seen my Autometer at 220F. Stock gauge never moved. I think one time years ago I had a thermostat going bad and hit 230F. It moved up some maybe between your blue and green but still didn't get to the H. I typically ignore the stock gauge since I have an aftermarket one.
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Old Jan 19, 2022 | 10:26 AM
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Originally Posted by Dak
Yours sounds off. Going by my Autometer gauge mine seems to function as j9fd3s describes. Once to operating temp it never moves from the blue area you have marked. I've seen my Autometer at 220F. Stock gauge never moved. I think one time years ago I had a thermostat going bad and hit 230F. It moved up some maybe between your blue and green but still didn't get to the H. I typically ignore the stock gauge since I have an aftermarket one.
Yes I think it’s also off too. I guess seeing it go that high just makes me kinda nervous.
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Old Jan 20, 2022 | 07:41 AM
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I've often wondered if something similar would work for the FC gauge:

https://www.rx7club.com/3rd-generati.../#post12472620

I'm going to install an aftermarket gauge in my car, but I'm hiding it in the glove box for occasional glances, because I prefer to have a stock interior with no extra gauges. Having a stock gauge that is a better indicator of actual temps seems like it could be worthwhile, especially if you're like me and don't really want aftermarket gauges.
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