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Old 08-12-2019, 07:14 PM
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Temp gauge problems??

My 2001 4.3l vortec overheated. I did not notice the gauge until the engine was already overheated. Ouch!! First time for this engine. I have kept up with the engine, and now I will always stress about how many miles I shaved off its life. Right after that, I noticed the gauge was reading erratically. Low, high, back and forth, and about a day later, it stopped moving all together.

I replaced the sensor at the manifold, right next to the thermostat, but still no reading. I read that older models have 2 sensors; one for the computer, and one for the gauge, but eventually 1 sensor was used for everything.

I am hoping a Chevy guy can help enlighten me.

Are there common issues with the system? Especially after an overheat?
Such as problrms with the gauge?

If my gauge is reading cold at all times, is the computer running as if the engine is cold?


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Old 08-30-2019, 04:42 PM
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Since your engine would have a mechanical fan I am assuming then it should only have one temperature sending unit and it will be either by the thermostat housing or on the side of the cylinder head or if you had two then I would guess one in both places but I could not say for a hundred percent but from what I typed into google its only showing one spot and depending on what year some have it at the thermostat housing and others on the cylinder head at the side between the spark plug area.
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Old 08-31-2019, 05:25 AM
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A key question - what made it overheat and what did you fix or try to fix to resolve the overheating? Something made it happen and you need to change that condition/factor to prevent overheating again.

Unless you really fried the engine and then just kept driving, I doubt that one instance of moderate overheating will be that significant for engine life. Temp sending units are usually pretty durable, but there is a chance that it was already on the way out (the fluctuating gauge), and the overheating just put it over the edge.

You need to look up your make/model and determine if the temperature sender is a direct connection to the gauge, or it only provides input to the computer. When newer vehicles went to a single sending unit it was often connected to the computer, and the computer drove the reading on the gauge.

GM and Ford both had problems with the stepper motors that make the computer-controlled gauge needles move, which can lead to very incorrect readings. At engine start-up the computer zeros the gauge (you see the need flip back to zero), and then it takes a sensor reading and steps the gauge needle up to the right position. If the stepper motor gets "lazy" it may not make it back to the zero point soon enough, and the computer "steps" the needle up to the wrong point on the gauge. I had a 2005 Mustang where this started to happen on both the temp gauge and tachometer, and the stepper motors had to be replaced. There are several vendors out there that do this repair to GM and Ford gauge clusters.


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Old 08-31-2019, 09:25 PM
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Originally Posted by 75gmck25 View Post
A key question - what made it overheat and what did you fix or try to fix to resolve the overheating?
I wondered the same thing, and how did he know it overheated?

And not just a funky gauge saying so. An overheating condition, and gauge going south. Does not pass the smell test.
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