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Discussion Starter #1
I just went out to start my truck and the low coolant light came on after it started.

The truck has been sitting for nearly 24 hrs and the temps overnight got down to 0 degrees F (colder with the wind chill) and the temp was 4F when I started it.

The truck started with a little more effort than usual but it did fire up. The coolant light only stayed on for about 10 seconds.

Is this anything to be concerned about? Any explaination?

Thanks,

Dave
 

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coolant level was up to full cold mark?
 

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Discussion Starter #3
To be honest I didn't check. It the first time the light has ever come on. It's also the first time in a long time it's been this cold. I just wondered if there was a connection. I'll check the coolant tomorrow before I go anywhere.

Dave
 

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Was it plugged in? Some of our big trucks at work leak when they are plugged in. Notice any coolant on the ground? Just a thought!
 

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My low coolant light has been on since I bought my truck used back in May of 06. It is not low. I make sure I keep a check on it just in case. I have no idea why it is on all the time.
 

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Could be the connection on the sensor.

Check it cold and fill to the cold mark. It goes up a couple of inches when hot.
 

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I should also note that my low coolant light has been on every mornin' for 10 or 15 seconds too. I finally found the ever so small leak and so far its been good. It was leaking at the back of the passenger side head.
 

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Discussion Starter #8
Not plugged in. No smell of coolant. I didn't check for leaks. I'll do all these things tomorrow.

Thanks,

Dave
 

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Bad mix of antifreeze has been reported to throw off the low coolant light. How strong or weak a mix do you have?

Mine came on yesterday morning on cold start too - cold level a bit too low on cold cold morning.
 

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Discussion Starter #10
The more responses I get, the more I realize I've been neglecting my coolant system. I have plans to remove the rad when the weather gets better and of course drain and refil the coolant in the process. In the meantime, I'll check the level and see about having the mix tested or buy a tester.

Dave
 

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Does coolant contract when cold? Maybe after 15 seconds it had enough heat to expand and bring the level up to the sensor? Just a thought. My coolant level did the same thing for a few days last winter. Turned out the lower rad hose clamp worked loose. Wouldn't ever drip, just loose enough to weep.
 

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The lower rad hose is where our trucks at work leak when they are plugged in. If we leave them unplugged, not a drop. I think we have a few shovels that do the same too.
 

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Discussion Starter #13
cool_fool;1572595; said:
Does coolant contract when cold? Maybe after 15 seconds it had enough heat to expand and bring the level up to the sensor? Just a thought. My coolant level did the same thing for a few days last winter. Turned out the lower rad hose clamp worked loose. Wouldn't ever drip, just loose enough to weep.
That's kind of what I was wondering. If something got slightly frozen stopping the flow and setting off the sensor, then once it warmed up enough, all was good.

I haven't gone out to check but from where I'm sitting I can see under the front of my truck perfectly and there are no signs of any coolant on the ground (would be easy to see in the snow).

I've had it plugged in all night. It's still only about 5F here right now. Yeah I know you guys out west are goin....wimp! 5F is like July in Sask. :D We just haven't seen temps this cold in a while. In December I was really thinking....hoping, that winter had been forgetten for this year.

Dave
 

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I bet anything your level was JUST low enough to set the sensor off. This effect is amplified by the cold weather you have there now. When you see the level in the tank after the engine has been run (hot engine) it will be ~1.5" higher or so. Funny that it expands/contracts that much but it does. After the 20 seconds or so the flow got moving enough to raise the level a bit to kick the sensor off.

Mine has a very slow leak/weap somewhere. From "full cold" mark, it will drop quick over a couple of weeks (about 1/2") and then it will take about 6 months to kick the sensor on a cold start some morning.
 

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Discussion Starter #15
I finally got around to checking the level this afternoon and it looks like it is down just a touch. That with the combination of the cold weather must have been just enough to turn the light on. I checked for leaks and nothing I can see. I'll top up the level tomorrow.
 

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This just happened to me this morning at 14F when started. Never saw the light before -- stayed on about 15 seconds. Did not restart the remainder of the day. Now at 40K miles, and no prior problems. I probably would not have messed with the coolant system (i.e. flush) until maybe 60K. Are folks suggesting flushing and changing sooner?
 

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You need to look at the level of the coolant when it is coldest. There is a good bit of difference in the level as it gets colder.

Monitor it closely or test for leaks if you suspect it has lost some coolant.

Check and see if the radiator hose gets hard right after you start it up.
 
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