When I got my 05 CRD at 145k miles it would get warm under strain - any sort of grade for an extended time and the temperature gauge would hit 3/4 mark. I swapped the thermostat and this resolved the problem - drove from Colorado to Nevada with no issues.

Then in May (151k miles) I started having cooling system issues again. Same story, highway speeds at a slight grade and the temperature gauge would climb. It'll go past the 3/4 mark and approach the red if I don't run the heat on full blast. Putting the heat on full blast I can keep it between the midway (even one tick below middle) and just below the 3/4 mark. If I run the AC I can almost immediately see a response with movement in the temperature gauge, regardless of driving conditions.

I've iteratively done a couple things, at each stage the problem hasn't been solved. Coolant flush, changed the thermostat (again), more flushes, changed the fan clutch, made sure the radiator coils are clear of debris, checked hoses for soft spots where they might be collapsing (lower radiator hose is just starting to breakdown but overall is fine. Will swap it nonetheless once the part comes in), more flushes... Water pump works on idle and there are no apparent clogs or leaks in the system.

I'm just about at the end of the line with things to check here and am considering swapping the radiator outright. Maybe 17 years of depositing minerals is impeding cooling despite not blocking passages...

I've read on here that the temperature gauges can behave erratically but I don't think that's my problem since I can see it react to driving conditions and the AC being on or not. It definitely is getting hot and is not just a faulty gauge. I've also read about the GM Fan Mod, which I'll definitely consider but since I'm having it overheat without towing I'm thinking that would be more of a band-aid than a real solution.

My question for the group - the Spectra Radiators (Spectra Premium CU13279) that were often recommended in the past seem to be discontinued. The only radiator I can find that fits is the Nissens 61026, but I read one comment in one thread that said that it doesn't fit correctly? Is that true?

Also, if anyone has any recommendations on what might be causing the overheating at this point I am all ears. I haven't deleted the EGR yet, for what it's worth

_________________
2005 Liberty CRD Sport

Get a cheap IR thermometer and compare the inlet and outlet temps to see if heat is being lost to air flow as it should be.
Crank cold and start shooting temps across the radiator looking for how the heat spreads across the radiator as it comes up to temp.
Cold spots have less coolant flow etc...
Clean the a/c coil with foaming coil cleaner?
Fins so small these days often will think its flowing well before hand but definite airflow improvement afterwards.