The transmission fluid change was done by the dealer. Is there a way to tell if they used the correct fluid? (Maybe color?)

 

I don't think it's a question of upgrading the radiator, I think it's a question of, was the replacement radiator equal to the OEM one? If the original radiator was starting to go bad this would cause a rise in engine temperature, especially when climbing the grade. Now if a new radiator is installed that cannot dissipate the heat as efficiently as the original one, then the engine temperature is still going to rise when climbing the grade.

 

ATF+4 is more expensive: it is thicker and very dark red compared to the Dexron that I've seen. But I don't know what Dexron + the additive is supposed to look like. I don't know of any way to be certain other than asking the dealer exactly which transmission fluid was used and deciding if you trust them to answer honestly.

 

Fixed! Took it to a garage with high user ratings and BBB A+ rating. Here's what he did:
- checked all fluid levels. Normal
- checked for stored codes. None
- Put on dynamometer with 50HP load while simultaneously checking exhaust emissions
- Van reached 251 degrees in less than 3 miles, however there were no hydrocarbons in exhaust (that’s good as it ruled out a blown head gasket and cracked cylinder head)
Conclusion:
There is a flow issue in the cooling system.

Next steps:
Pressure tested radiator cap. While it was labeled at 17 lbs, it released at 14 lbs. Replaced cap. (Old cap was less than one month old)
Using an infrared temp gun, noted cold spots on radiator. Removed radiator and had it flow tested. Flow was low. Replaced radiator with new plastic topped one. (Old radiator was less than one month old).
Removed water pump and checked for impeller spinning on shaft. No issue.
Removed knockout plug on each side and flushed engine, inspecting for leftover sand from motor mold. No sand found.
Noted at the first step that one could count the fan revolutions when the engine was hot. Replaced aftermarket fan clutch with factory model (Old clutch was less than one month old).
Noted that the thermostat was of a brand he did not trust and replaced it with one he trusts.
Reassembled, new coolant mix added.

Dynamometer test: with 50hp load, after 10 miles, temperature was 217 degrees (that’s normal)

Road test, including 8 degree grade: temperature never got as high as midpoint.

Lesson learned: the dealer did all the right stuff, just did not check the performance of the new stuff--and it was defective.

 

Sounds like it took some really deep pockets to fix that.

 

$1100. But considering I turned a vehicle worth about $15K back into a usable machine, I think it was well worth it. I intend to have the Dodge dealer pay that bill, but it may take some time.