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Discussion Starter #1
ok so iv noticed since it has gotten hotter out ( its been 80- 90 here) and running down the highway shes running close to 210 but wont go over no matter how hard i run her but cools down to 185 if i let her sit or drive around 40 mph, im thinking thermostat cause it just started since i just got it out of the shop, i think they drained the coolant while the engine was hot and screwed up the thermostat just double checking to see if anyone has had this problem
 

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Discussion Starter #2
im going out now to gm to get the thermostats cause there the only ones who have them is stock and i need them before i go to capital raceway tommarow, and another question that im pretty sure i know the answer too do i have to run the orange GM coolant? cause im gonna switch to the purple nitrate precharged coolant
 

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Im not real sure its overheating, mine runs at 210 all the time, it wont get below it unless its cold as hell and it wont go above it at anytime
 

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Discussion Starter #4
its been running at 185 since i got it and somtimes it would run higher then go back down but not up to 210 constant
 

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Hmm maybe the LLY's run cooler, than the LBZ's and LMM's
 

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Discussion Starter #6
its got one 180 and one 185 so i dont think it shoudl run close to 210 at all. so i think my one themostat is sticking.... WHY! the hell did they designa 2 thermostat system....wtf its stupid unless its a big 12 liter engine and needs high flow to cool... ohwell
 

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Discussion Starter #7
Hmm maybe the LLY's run cooler, than the LBZ's and LMM's
i think they run hotter cause of the emission system to burn the soot out unless it has a regen switch? maybe ??? i dont know i dont know duramax all that well
 

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My truck does the same thing. 180ish most of the time 210 on the highway or if i hammer on it. I dont think it is a problem.
 

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Discussion Starter #11
iv had it 2 months now and has never run this hot at highway speed. ... i noticed that they changed my coolant it was orange now its purple...ish ...... i wonder if they mixed the coolant wrong. it just went in for injectors, harness, and FICM. do they have to drain the coolant to change injectors?
 

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Discussion Starter #12
and another thing.. if it runs this hot at highway speed with no load, what kinda temps am i looking at while towing 9k..... i think i have a problem none of this seams right
 

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my lb7 is normally always between 192 and 210 depending on how hot it is and it drops to around 187 when just cruising around town.
 

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Discussion Starter #14
im got the thermostats and new coolant. im gonna check a couple other things. first and if i fond nothing im just gonna do the stats and change the coolant
 

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Discussion Starter #15
after doing alot of research my hoses are not hard my coolant tank is not pressurized( besides the lil pop when i took off the cap) and my fan clutch is engaging and no air pockets in the system ( as far as i can tell ). so im going with thermostats. i know it will do this if one is stuck and one is open and its running hot so im just gonna do them tommarow befor i goto capital and ill let you guys know what happens
 

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Of course it's never run that hot, cuz you've only had it for 2 months. It just got hot outside. Every Duramax I've been in either fluctuates between 185 and 210 or stays just under 210. You'll be fine :rolleyes:
 

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Just my two cents, Mine has always ran at 210 and only moves about a needle width(down) while driving, idle it drops to about 170 to 180 ish.

For a minute there I was wondering if I had a problem since mine was doing the same thing. then I read everyone else's post..... lol
 

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Yep, my 09 runs 210 as a normal operating temp. Nothing to worry about as ALL vehicles in the past 20+yrs or so have had 195 or higher thermostats installed by the factories as a way to help emissions.
 

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Discussion Starter #19
does anyone know if there is a gasket on the thermostat housing?
 

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if it runs this hot at highway speed with no load, what kinda temps am i looking at while towing 9k.....
the same, just a little more fan action as the load and outside temps increase.

Your truck is running normal. :horse1

:D
 
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