Low coolant level??

I had an EGR cooler go, and I looked like a steam train going down the road!
Also, check that the transmission cooler is air cooled, and not liquid cooled. If liquid cooled, pull the check plug and see if trans fluid comes pouring out. If it does, then the coolant is going into the transmission.
I'd say EGR cooler, or trans cooler if it is a liquid cooled one.

Martin

 

When my EGR went bad is was blowing white smoke very badly.

 

If it's an ISX I can almost guarantee you it's the EGR cooler. It will gradually get worse over 2-3 months then total failure and the motor hydro locks if you wait too long. Mine would throw white smoke intermittently. It seems more on hills or when it was cold. To me it seemed more when it was humid out. There really wasn't a pattern.

 

I own a 2013 t660 kw with the paccar engine. It loses about a half gallon every few months. No leaks either psi tested cooling system myself no leaks internally, none of the fluids are contaminated, just a mystery, conclusion i came to is it's just the high operating temps and engine gets used hard 90% of the time. Not idling but fast hard mi....... Does the trk in question have an apu and share same cooling system?. My last apu t/k tri pack has a bad head gasket and started using coolant after 28,000 hrs. Just another idea

 

we have an KW T660 w/ Cummins ISX and replaced our EGR and we are still having to had antifreeze-we had it tested by Cummins shop (hot and cold testing) and they can't find where the antifreeze is going. No visible leak underneath. Any ideas???