Hello!

I've got a 2003 5.7 Quad Cab, and while towing my travel trailer through the mountains this past weekend my truck started to run a little warm, then my upper radiator hose blew. The hose as far as I can tell was OEM, and upon inspection after the fact is rittled with cracks on the inside. No wonder it went on me.

Now, I know it's totally normal, given what and where I was towing (~8k lbs trailer, 6% grade, 10 miles), but it reached 3/4 on the temp gauge on the most grueling part of the climb. Does anyone know what needle position corresponds to what temperature? I was off the road within 15 seconds of smelling the coolant, there's no damage to the engine, and with a new hose delivered within 2 hours I finished the last 50 miles of my trip no problem.

I never once heard my fan engage. This morning, with the engine cool, I gave the fan a spin and there was steady resistance, less than a full free rotation if spun by hand. Later today after a drive I got out, engine hot, and spun it and it almost free wheeled. I was under the impression when hot they should engage, as the fluid inside physically expands locking the clutches together. Mine seemed less effective when hot.

Edit - Pulled the factory clutch off... after a rotation or two it free wheels lol, it's toast. It'll spin and spin and spin.

 

Probably worthwhile to replace all hoses, flush the system, and refill with fresh antifreeze. Obvious that some maintenance has been overlooked.

 

Agreed on the hoses. That's been done now as of tonight. Hoses, flush, refill, new thermostat, and new fan clutch.

I mean, I was grossing 14k going up a 6% grade for 10 miles with the motor singing at 4500 rpm...

 

You asked about temperature, there is a variety of readers that you can plug into your OBD port and get detailed information. I have one that links to my phone and use it to monitor transmission temp when I'm towing with my SUV. Given the towing conditions you described, I think knowing trans temp would be useful.
If you see your engine temp rise again, try turning your heater on high. This turns the heater core into a mini radiator and will help bring down temp.

 

It's probably a good time to change your ATF.