2012 Isx15 acting stupid please help

[JimT]

(08-24-2023 )Rawze Wrote:  A lot to unpack there...

== The thermostat is supposed to be 185-F from cummins. Quite often when someone replaces the thermostat.. they do not replace that brass ring (or they do not install the new one properly, damaging it) in the bottom of the thermostat housing and this causes them to run hot all the time or overheat.

Just wanted to chime in, when I did my inframe in 2020 I installed the new thermostat from the kit. Prior to inframe coolant temps would bottom out about 185. After inframe with the new thermostat my coolant temp has been 178 on the low end (and very steady there too). Not sure why the difference but I'd guess something slight changed with their thermostats.