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Discussion Starter · #1 ·
Is anyone's water temps on their truck running warmer on hotter days and colder on cooler days. I noticed the other day when it was 28* outside that my water temp was around 170*. Last night it was warm outside was 65 and engin temp was 200*. Is this normal or is there a problem with the thermostat.
 

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When I owned my duramax. That was one of the things that I hated about it. On the duramax it injects twice the amount of fuel untill it reaches opp. temp. Therefor one of the problems for bad mpg in the winter. Here in Idaho in the winter. It never gets to warm. It seemed my d-max would heat up, but then the temp would fall on the gage. It was never a steady temp in the cold months.
 

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On the duramax it injects twice the amount of fuel untill it reaches opp. temp.
....first ive heard of that....

you get bad mileage in the winter because of WINTER BLEND. The diesel you buy is half kerosene. Kerosene/diesel (winter blend) does not have the BTU's that staight #2 does. Less heat output=less power=worse MPG.

The temperature swinging is not a problem, its typical cold weather diesel operation. Its just the thermostat opening and closing. It will get to around 192 or so, t-stat will open alloing coolant flow, cooling the engine down. It cools down VERY quickly because its cold in the winter and there is really cold air flowing across the radiator/CAC stack. SO all this cold air chills the coolant more so than in the summer months, so when the t-stat opens, the engine gets a blast of "cold" coolant (well not really cold, but cooler than in summer) and cools right down to 180 degrees really quickly, when the t-stat closes again (180 degrees). Then the engine heats up again and the process repeats. The reason you dont notice the rapid swings in the summer is because when the t-stat does open, the engine cools down to 180 a lot more slowly and the gauge doesnt really register it as quickly when the temp drops slowly... Are you using the winter front cover?

--Ben

btw what you are thinking of is ADVNACING THE TIMING until the engine warms up. This is NOT the same as "injection twice the fuel". Advanced timing=more diesel noise=loud engine in the cold when you first start it.
 

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Discussion Starter · #4 ·
The temp swing I am referring to is swinging up and down due to outdoor temp. I know that the water temp will swing until thermostat reaches operating range. My water temps are low on cold days even after 20 to 30 miles of driving. They are higher as the outdoor temps go up. I have noticed this more lately due to our warmer days and cold nights. What is normal operating temp for the 06 LLY?
 

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180-190, depending on t-stat position. Are you using the winter front cover?
 

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Discussion Starter · #6 ·
No I am not using a cover. I live in central North Carolina.
 

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I have seen the same situation with my LBZ. This is my first diesel, so I didn't think a whole lot about it. Engine runs warmer on warn days and colder on cold days. I was waiting until late spring / early summer to see what the engine would do in hot weather. Good luck
 

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I wouldnt worry about it...as long as the engine isnt running 160 or 220, its fine
 

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Mine swings pretty regularly as well. I live in So Cal so I don't know what cold is. But in the morning I can barley keep it above 180 unless I constantly get on it. At highway speed or when the outside temp is warm, 65-70+ it runs one guage width under the 200 marker.
 
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