I have a 98 6.5 1500 and for some reason its running hotter now that its cold. (canada about -15) its running at probably somewhere around 90 degrees celsius and it normally runs at like 80 ish. i donno if thats a problem or if i need to block the rad or what. if anyone has a clue it would help alot. i have not owned this truck in winter until this year.

 

maybe you have one bad t-stat there is 2 in t-stat from 96+ that be only thing i can come up up with

 

see if you got a bunch of crap in rad

 

the rads pretty clean. i cleaned it out about 2 months ago when it was warm and grille was off. It might be the thrmostats not sure yet. it mostly only happens at higher speeds. could it possibly be that since its not blocked off yet that the clutch fan is not engaging when it should because of the cold air?

 

did u check cool mixture if so change therm first rad might be pluged beyond cleaning.O bad heater core.

 

the thing is it has been fine for the last 8 months. since i bought it i have kept it clean and all that. and its winter here, -15 on average day. and now its running hot. it always ran cooler in hotter weather since ive owned it. its just confusing. the only little difference that has changed is that when i did my f intake swap i lost a bunch of rad fluid, so when i filled it back up i put 50/50 prestone green, and it normally runs the red/ pink stuff. but i only added one of the little jugs. like one litre or something like that. maybe thats the prob.

 

watch mixing some r not ok to mix plus that could change mixture when u ad to current fluid.

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if u need more info email me at chevy6.5tdguy@yahoo.com

 

so i blocked the rad and drove to the movies and back. on the way there ran a little hot again but just a tad cooler then before. on the way back how ever it ran the hottest so far just about hitting 100 Celsius. so now im pretty confused. probably gonna change up the t stats. whats the best for winter? i also might need to get a rad flush which hopefully helps.

 

sounds like therm is not opening up all the way.

 

did you open the bleed screw see if there air in there that make run hot