Overheating

[Zero Obliquity]

Heading home from work Thursday, on interstate rolling 75, I noticed my coolant temp start to rise. I pulled off at the next exit and the temp started to drop. After a few minutes the temp was back to normal so I headed out. When ever I would go over 60 or pull up a hill the temp would climb. When I got home I checked it out. everything seems fine. The fan looked a little slow. Friday I put a new radiator and fan clutch on. When I start out the truck runs great. It will stay at temp for 10 to 15 minutes and then when you start running about 60 the temp will climb. Could it be a head gasket? No white smoke, truck runs great, no coolant in oil. What should I check next?

2001 F350 7.3
Overheating at speed
New radiator and fan clutch
No white smoke
Truck runs great

Thanks
Lonnie

[Turbostang500]

Maybe just the t-stat.

Seems it starts getting hot whenever you start demanding a little power.
It might be stuck closed.

You can remove it and boil it in water on the stove. Watch for it to open.

[Jrz13]

I agree to start looking at the thermostat. If thats not it your H2O pump may have a few bad blades in it.

[Zero Obliquity]

Thanks I will check out the water pump and Tstat today. I tried squeezing the upper hose when it was running hot and I did feel pressure.

[Zero Obliquity]

Thank you both! It was the Tstat. I have never had one do that. I have only had them stick closed or open. You learn something new every day. I owe you both a few cold drinks for the help. Much appreciated.

[Turbostang500]

Glad to help!