temp gauge reading hot but the engine runs fine

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  #1  
Old 06-11-13, 10:07 AM
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temp gauge reading hot but the engine runs fine

my temp gauge on 94 blazer 5.7 goes from normal to hot randomly while driving but the engine runs fine and is NOT over heating, could this be the temperature switch located on drivers side?
 
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Old 06-11-13, 08:36 PM
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have some one wiggle/ tap on the switch with the key on. if it jumps to hot you have your awnser. how are you sure its not getting hot? thoses are pritty tough motors and might not show "real" signs of getting hot.
 
  #3  
Old 06-11-13, 10:19 PM
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The first few times it happened I pulled over and popped the hood, the radiator cap was still cool to the touch and no obvious signs of over heating. I have had the truck for about 3 weeks now and the gauge hovers around 250 routinely, it will go back and forth to about 210 and back up.
 
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Old 06-11-13, 10:36 PM
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It could be a thermostat issue. The radiator might stay cool but the engine could running hot if the thermostat was sticking closed.
 
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Old 06-11-13, 11:41 PM
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Yeah I was thinking that might be possible also. Figure sense they are cheap I'll throw one on tomorrow and see what happens.
 
  #6  
Old 06-12-13, 09:38 PM
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I put a new thermostat on this morning, no change. Drove the truck to work and it shut down on me. Now it's at a garage and the mechanic says the fuel pump failed and needs replaced.... coincidence???
 
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Old 06-12-13, 09:44 PM
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Yes.....coincidence. While it's there have him put in a temperature sensor.
 
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Old 06-13-13, 05:15 AM
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When you did the t-stat, did you do a flush and fill of the coolant?
I know a lot of folks forget about the coolant and after so many years the stuff does get nasty.
 
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Old 06-13-13, 08:44 AM
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I did not flush, looked pretty clean, but I did let it cycle through and topped of the fluid. I told the mechanic about the sensor also. This has turned into a nightmare. The mechanic tapped on the plastic shroud around the tank to see if the fuel pump would engage. It did not, however in doing so now the tank leaks and he said its rusted out! Also he's telling me that the tank and lines had been tampered with. So somehow this turned into a $600+ fuel problem?! WTH?!
 
  #10  
Old 06-14-13, 04:28 AM
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canton bob,

I don't believe the fuel pump issue to be a coincidence. As much as I hate to say it (but I must be honest with you) not all mechanics are trustworthy. Get your vehicle out of that shop and over to a trustworthy individual. With regards to your issue I agree with all that has been said so far. I would add that you do a scan and post any error codes that may be set, and rule that the gauge itself is not defective. Visit the link below to test the "ECT"

Part 1 -ECT Sensor Test (P0117, P0118) (GM 4.3L, 5.0L, 5.7)

Thank You
Amy
 
  #11  
Old 06-16-13, 11:49 AM
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With your temp gauge up and the radiator cap still cool after running, it's likely the thermostat isn't opening. It could be defective or air locked.

Wait until the engine is completely cool, take off the radiator cap and fill the radiator as full as you can. Then start the engine and wait for the water in the radiator to warm up. If it doesn't, the water isn't circulating into the radiator and the thermostat isn't opening.

Drop the Tstat in some hot water to check it. If it works, see if there is an air bleed hole in the base. If not, drill an 1/8 hole in it for a bleed. Then reassemble, refill and park on a sharp incline with the radiator cap off to burp the system.
 
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