Temperature sensor
Thread Starter
Pro
Joined: Mar 2011
Posts: 635
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From: Allyn WA
Temperature sensor
I have owned this car for 22 years. The temp gauge has never gone to the right of 210. I replaced the original engine with a zz4 crate about 5 years ago and never had an issue. At the start of the driving season the gauge wasn't working. I replaced the sensor and thought it was reading low as it never got more than half way to 210. I have an IR gun and have checked the temp everywhere under the hood and it seemed to b e bit low. As time went on I felt it got closer to correct. Yesterday I had the intake manifold gasket replaced as it was leaking oil out the back end . I drove it there in the morning and picked it up that afternoon. I didn't get more than a couple of miles and it was halfway from 210 to 250. I went back to the shop and the checked it with an IR gun and it didn't seem to be that hot. I got home and let it set and checked the water level in the surge tank this morning thinking it might have an air bubble. I then removed the pressure cap and started it and watched the temp climb. The thermostat opened and the fluid level seems correct. I replaced the cap and I couldn't find a part of the engine/cooling system that registered as hot as the temp gauge claimed. I did noticed something that struck me as odd. When I shoot the temp sensor on the side closest to the radiator I get 20 degrees hotter than the opposite side. When I shoot in the middle of the sensor I get 10 degree hotter than the back side
2 questions. One, how could just removing the intake have such a huge difference on the sensor reading? And second, I seem to recall a thread about current sensor's not being completely compatible with the old gauge? Something about need to add a resistor to get them to be accurate?
2 questions. One, how could just removing the intake have such a huge difference on the sensor reading? And second, I seem to recall a thread about current sensor's not being completely compatible with the old gauge? Something about need to add a resistor to get them to be accurate?
Race Director
Joined: Jan 2002
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From: Close to DC
C2 of the Year Finalist - Modified 2020
As you may know, this temp sensor issue is well covered. Search back and read what you find. More likely, you can but a couple of them and test as suggested in the relative posts. 
Dennis
Dennis
Melting Slicks
Joined: Apr 2003
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From: Florida
I have owned this car for 22 years. The temp gauge has never gone to the right of 210. I replaced the original engine with a zz4 crate about 5 years ago and never had an issue. At the start of the driving season the gauge wasn't working. I replaced the sensor and thought it was reading low as it never got more than half way to 210. I have an IR gun and have checked the temp everywhere under the hood and it seemed to b e bit low. As time went on I felt it got closer to correct. Yesterday I had the intake manifold gasket replaced as it was leaking oil out the back end . I drove it there in the morning and picked it up that afternoon. I didn't get more than a couple of miles and it was halfway from 210 to 250. I went back to the shop and the checked it with an IR gun and it didn't seem to be that hot. I got home and let it set and checked the water level in the surge tank this morning thinking it might have an air bubble. I then removed the pressure cap and started it and watched the temp climb. The thermostat opened and the fluid level seems correct. I replaced the cap and I couldn't find a part of the engine/cooling system that registered as hot as the temp gauge claimed. I did noticed something that struck me as odd. When I shoot the temp sensor on the side closest to the radiator I get 20 degrees hotter than the opposite side. When I shoot in the middle of the sensor I get 10 degree hotter than the back side
2 questions. One, how could just removing the intake have such a huge difference on the sensor reading? And second, I seem to recall a thread about current sensor's not being completely compatible with the old gauge? Something about need to add a resistor to get them to be accurate?
2 questions. One, how could just removing the intake have such a huge difference on the sensor reading? And second, I seem to recall a thread about current sensor's not being completely compatible with the old gauge? Something about need to add a resistor to get them to be accurate?
I believe IR guns are calibrated for something like a flat black surface. If you shoot a brass or chrome object or even the aluminum manifold your reading will differ.
Racer
Joined: Oct 2014
Posts: 251
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2017 C2 of Year Finalist
Assuming the gage is electric, if your sensor is mounted in the intake? And it's only a one wire unit, you could have removed the sending units full GROUND when replacing the intake....Just my 2 cents
Melting Slicks
Joined: Jul 2004
Posts: 2,869
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From: Maryland
Most likely the sender wire when removed from the sensor cleaned up some minor corrosion ( added resistance) at the connection. The sender is probably not calibrated for the gauge. Added resistance will bring the gauge reading down but will be accurate only at that temparature it is set to.
Thread Starter
Pro
Joined: Mar 2011
Posts: 635
Likes: 4
From: Allyn WA
Always a mystery with this car. What works/happens in the morning is not always the same in the afternoon. I have been constantly shooting everything with the IR gun and it doesn't seem to be overly warm.
