The truck has ~175k miles on it. The background story is that we have been towing a 4200# dry weight Travel Trailer for about 5 years with minimal issues. At first, the transmission overheated, hitting near 230F on one of our first 'mountain' tows on a 90F day, so I put the trucool 40 in line with the oem aux. cooler, which solved the problem.
Well, we just upgraded to a 6300# T.T. a few weeks ago, and drove it home 2 hrs. or so without issue. This past Thursday evening, we towed about 250mi. to our destination arriving at midnight, again without issue. Yesterday on our return trip however, things changed.
First, it was hot out; 95F or so. We got on the same route we came in on with some rolling hills, and 55mph backroads. I noticed the temp gauge picking up from the 210F mark within the first hour of the trip. The transmission kept below 200F, likely due to the trucool, but the engine continued to climb and fall with the load; hills, speed, traffic, etc. Outside temp was 'measured' by the truck at up to 105F, but I think that was influenced by the engine temp., as the weather app. said it was 95F.
I tried to vary the transmission, going from normal drive, to tow mode, to manual shifting to keep it cool. At first, it seemed like higher rpm (3000rpm) would circulate fluid better, but that didn't work longer term. Basically, the only thing that affected the temp was letting off the gas, and slowing to 45mph going up hills. It would sometimes cool back to the 210F point and stay there until the load picked up again. I could hear the fans running too, so it seems that everything was 'functioning' properly. Fluid levels were all topped up; coolant, Transmission oil, and engine oil. No messages or codes were generated that came up, and I was able to keep the engine below 235F the whole time...I had determined this would be my pull-over and cool off temperature
I'm game to do the conventional coolant purge, thermostat change, oil & tranny fluid change if that's all that's needed. But these are all done on a conservative maintenance schedule. And the truck runs/cools normally at all other times, and with more modest loads, never leaving the 210F mark.
Anybody have any upgrade recommendations? The addition of the trucool was a great change, so in the same vein, I'm thinking a larger, secondary or more efficient radiator recommendation, better or additional fans.
Edit; electric fans only; no clutch/fan on this one.
At least not on either of my rigs. The Denso I installed was made in China, but I'm okay with it because it had to be made to their standards.
