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Fluctuating Coolant Temp Guage

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#1 ·
A few days ago I noticed as I was on my way to work my coolant temp gauge needle went a 1/4 of the way past the 1/2 way mark on the coolant temp gauge the needle then dropped to the 1/2 way mark on the gauge and stayed there the rest of the drive to work. Arrived at work checked the coolant level on the coolant expansion tank the coolant level was on the full mark. I also noticed that the coolant temp gauge needle only goes past the 1/2 way mark on the coolant temp gauge only once after the thermostat initially opens on a cold start warm up, after that the coolant temp gauge stays on the 1/2 way mark on the coolant temp gauge and fluctuates about a 1/16th of an inch below the 1/2 way mark on the coolant temp gauge. This is unusual because the entire time I have owned my truck the coolant temp gauge needle has never reached the 1/2 way mark on the coolant temp gauge it has always stayed an 1/8th inch before the the 1/2 way mark on the coolant temp gauge and never fluctuated, it never mattered if it was 20 below zero or 110 degrees cruising on the freeway. I have replaced the coolant twice since the truck was new with Zerex G05 coolant and the coolant in the expansion tank was full where it has always been. I replaced the thermostat, coolant temp sensor and the coolant. Went on a test drive and the coolant temp gauge needle did the exact same thing as described above, I then checked the coolant level for the next few days and the coolant level remained right on the full mark on the coolant expansion tank. Last night I replaced the radiator and checked the radiator upper and lower radiator hoses the spring in the lower radiator hose is good and neither radiator hose is collapsing, and again after another test drive the coolant temp gauge needle is still not where I expect it to be.

Has anyone experienced this and solved this issue? Does anyone have any ideas or suggestions on how to trouble shoot this further?

Thanks Doug
 
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#2 ·
free bumppppppppppppppp
 
#3 ·
Same problem

I have a 2011 3500 6.7L diesel and I have the same problem. The engine gets up to operating temp fine, so I know the thermostat is working. It does appear to have a 190 thermostat. Anyway, it fluctuates between 194 and 204 when it feels like doing so. I am going to be towing a travel trailer a lot and am concerned. Is anyone aware of a fix for this?
Pops
 
#5 ·
I am having the same issues as HemiDoug .before I start replacing parts does any one have a solution.thanks Mads
From this post and the ones above, it appears that the indicating systems are working, meaning that they respond to temp. changes. The issue is probably minor, as the temp. is not excessive, and stabilises quickly.
You need to check the level in the overflow bottle when the engine has cooled down, and then remove the rad. cap and make sure the rad. is full.
There is a hose or a tube inside the bottle, and it could be damaged or disconnected, or pinched. When the engine is hot, coolant goes in the overflow bottle, and is "suppose" to go back in the rad. once cooled off; that will only occur if the hose is good, otherwise, you have air in the cooling system, and that could be your issue...
 
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