2012 gmc lml overheating

[Rudykp97]

So my 2012 gmc lml has recently started to overheat to about 220 and sometimes a bit more and only happens every now and then and it's happened maybe 3 times to which I immediately switched it off and when I went to check it out I released the coolant refill cap and had suction I believe, im going to check it out some more tomorrow but just wondering what y'all think or if any of y'all have had the some prob thanks in advance

 

[2004LB7]

Is the dash saying it is overheating or are you assuming 220* is overheating? Because 220* is not overheating

 

[Rudykp97]

Well that's as far as I let it go it wld have gone past that if I'd have not pulled over given at the rate it was climbing and only does that as certain times kinda as if my thermostats were sticking but idk about the suction part at the refill cap

 

[2004LB7]

Did your fan come on? Is the coolant stack clean?

 

[Rudykp97]

Fan comes on and coolant stack is clean

 

[Rudykp97]

The truck has 155k miles