2005 Chev Tahoe, 5.3L, intermittent overheating, smells like antifreeze, but no leaks, no leaks in reservoir. I have replaced thermostat, gaskets, water pump a year ago. No sweet smelling exhaust, no white smoke. Seems that I can go <50 miles without an issue, but over 50 can (but does not routinely overheat). Thoughts?

 

Possibly a clogged radiator. Try a good flush.

 

Thank you. Will try it.

 

Do you ever have to replace fluid?
Smell antifreeze while driving? - If so consider heater core
How hot does the gauge show when it overheats?