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I don't trust my Temperature Gauge?

rumblecloud

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How do I know my temp gauge is telling me the truth?
Yeah I know weird.

EDIT: Just read a couple of things in the forum from RonD and others, so it would seem my cooling system is okay and I'm just paranoid - but that doesn't mean everyone isn't out to get me.

The gauge seems to work, never goes above normal - in fact never reaches normal or the midway point. So like if it's the gas gauge it would read 1/4 tank.
But it just seems like the engine is hotter than that. The thermostat opens and water circulates. Heater works fine. When I turn on the heat, the gauge drops a little like it's supposed to. When I replaced the heads a couple years ago I replaced the thermo and flushed and all that stuff, I just don't trust it.

How can I test it to make sure the cooling system is working properly?

Thanks,
r
 
Last edited:


Shran

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Run it hard on a hot day and then use an infrared temp gun to check the temp on various spots on the engine. Heads are usually where I look. Or put an aftermarket gauge in that shows actual temperature.

I think you can also use some of the more advanced OBD-1 scan tools to view live data from the ECM - the Bosch 1300 will do that and my ancient OTC System 2000 scanner will as well.

The gauge in our trucks just suck. I can watch the temp gauge on my 1st and 2nd gen trucks and view when the thermostat opens and they all show that in a different place on the gauge. On some it's well past halfway, on others it's right at half, but most of the time it happens before the needle even hits half. The only needle position I trust is the HOT side, if it's way over there, time to panic.
 

rumblecloud

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Run it hard on a hot day and then use an infrared temp gun to check the temp on various spots on the engine. Heads are usually where I look. ......
I have the temp gun and have been doing that , but not really keeping track. I know the heads and exhaust are extremely hot (duh)I but the other things I have checked did not seem overly hot, however now I will do that now in earnest, keep track and report back. Maybe it will help someone else.

Thanks,
r
 

Shran

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I wouldn't even bother with the exhaust, it's just going to be very hot... irrelevant, really. Heads & lower intake would be where I'd get a reading at. See if you can get a reading right before/after the thermostat opens, may require a helper. They should be right around 195 degrees when the thermostat opens.
 

Uncle Gump

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I have a mechanics gauge I put in the filler neck. While you can't run down the road with it... it will allow you to see actual coolant temp.

I also use the infrared to check upper verses lower radiator hoses at the radiator. You should see cooler Temps on the lower.

I've always put aftermarket gauges in my trucks. But I didn't put a temp gauge in my 06.
 

gaz

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@rumblecloud ,
You could install both or either an oil temperature and a coolant temperature gage, then you could always monitor them while driving.

From what you are reporting, sound like your cooling system is working very well; a pound of prevention is worth all the assurance in the world.
 

BiggSherm1988

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Mine does the exact same thing (2008) it just always stays around the 1/4 to 3/8 area no matter how hard i run the truck or what i do it will always stay there. it works but just sucks. i used a bluetoot OBDII reader to watch the numbers and verify the t-stat opened.
 

rumblecloud

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I took some temps yesterday with the infrared:
Valve cover 188
Radiator side 151
Top radiator hose 188
Bottom radiator hose 149

Driver side exhaust mani 677 ---seems really high, but what do I know. 😬
 

Uncle Gump

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I think your radiator hose temps are spot on...

30 degree temp drop right where it's suppose to happen.
 

Eddo Rogue

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I know the feeling, I was going through some cooling issues and wired/plumbed in an aftermarket unit. Once everything was settled I removed it. Actually accidently kicked it off getting out of the truck in a hurry, took it as a sign I didn't need it anymore.
 

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