Cummins ISX Overheating

What does half mean?

 

a flush might help but sometimes takes out (springs a leak) the heater core,

could also be a weak water pump,

thermostat?

 

Yeah, if you flush it with a harsh cleaner, sometimes it will eat out the weaker spots in the core, and will cause leaks.

 

Thermostats are designed to fail safe too. That means open. If yours has failed open then the water is circulating too fast to be cooled. Not a problem til you load it up.

Check it out.....

 

same thing i was thinking thermostat

 

clutch fan?

 

Not necessarily, last time my thermostat blew it closed. I knew something was up when driving at 100km/h at night empty on flat ground and the horten kicked in. Scared the #### out of me when you aren't expecting it to come on. like others have said try cleaning the radiator out with water, try and flush it from back to front not through the cac that can just push the crap in further. If that doesn't do it try flushing the system then look at water pumps and thermostats.
It could just be your gauge reads high or it is a bad sensor.

When you had the fan running normal did it kick in very often. in really hot climates they can kick on for 10sec off for 20sec when idling.

Don't worry it is very hard to cook the engine, they will derate themselves to the point you won't be able to keep driving and throw every code on the face of the planet before you do any damage.

 

Its possible that you have one thermostat stuck shut, and not allowing proper coolant flow. Very hard to diagnose when this happens however the isx is a very easy to replace and should be cost friendly if you don't have any other ideas you could try that.