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Low engine temp/ poor mileage

5K views 6 replies 6 participants last post by  Sierraluva 
#1 ·
My truck runs right around 165 degrees, it’s been doing it for months It use to run around 179/181. It also dropped 18-19 mpg down to 14-15mpg. I just checked for any thrown codes but didn’t have any. Any ideas why or where I should start looking to solve this? Thanks.
 
#2 ·
Likely need change your thermostats. Low engine temp will cause poor mileage. I changed mine on my lmm this summer when I did the hsp billet thermostat housing. Temp is 185-190 and mileage came back up.


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#7 ·
Mine is doing the same thing. You need thermostats. There are two. They right next to each other just below the ac condenser on the front of the motor. Go with AC delco. Got mine from Amazon. It’s a good time to flush and replace coolant too.
 
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